1
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Barakauskas VE, Bohn MK, Branch E, Boutin A, Albert A, Luke S, Dittrick M, Higgins V, Adeli K, Vallance H, Jung B, Dooley K, Dahlgren-Scott L, Chan WS. Mining the Gap: Deriving Pregnancy Reference Intervals for Hematology Parameters Using Clinical Datasets. Clin Chem 2023; 69:1374-1384. [PMID: 37947280 DOI: 10.1093/clinchem/hvad167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 09/27/2023] [Indexed: 11/12/2023]
Abstract
BACKGROUND Physiological changes during pregnancy invalidate use of general population reference intervals (RIs) for pregnant people. The complete blood count (CBC) is commonly ordered during pregnancy, but few studies have established pregnancy RIs suitable for contemporary Canadian mothers. Prospective RI studies are challenging to perform during pregnancy while retrospective techniques fall short as pregnancy and health status are not readily available in the laboratory information system (LIS). This study derived pregnancy RIs retrospectively using LIS data linked to provincial perinatal registry data. METHODS A 5-year healthy pregnancy cohort was defined from the British Columbia Perinatal Data Registry and linked to laboratory data from two laboratories. CBC and differential RIs were calculated using direct and indirect approaches. Impacts of maternal and pregnancy characteristics, such as age, body mass index, and ethnicity, on laboratory values were also assessed. RESULTS The cohort contained 143 106 unique term singleton pregnancies, linked to >972 000 CBC results. RIs were calculated by trimester and gestational week. Result trends throughout gestation aligned with previous reports in the literature, although differences in exact RI limits were seen for many tests. Trimester-specific bins may not be appropriate for several CBC parameters that change rapidly within trimesters, including red blood cells (RBCs), some leukocyte parameters, and platelet counts. CONCLUSIONS Combining information from comprehensive clinical databases with LIS data provides a robust and reliable means for deriving pregnancy RIs. The present analysis also illustrates limitations of using conventional trimester bins during pregnancy, supporting use of gestational age or empirically derived bins for defining CBC normal values during pregnancy.
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Affiliation(s)
- Vilte E Barakauskas
- Department of Pathology and Laboratory Medicine, BC Children's and Women's Hospital, Vancouver, BC, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Mary Kathryn Bohn
- Clinical Biochemistry, Pediatric Laboratory Medicine, The Hospital for Sick Children and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Emma Branch
- Women's Health Research Institute, BC Women's Hospital, Vancouver, BC, Canada
| | - Amelie Boutin
- Department of Pediatrics, Université Laval, and Reproduction, Mother and Youth Health Unit, CHU de Quebec-Université Laval Research Center, Quebec City, QC, Canada
| | - Arianne Albert
- Women's Health Research Institute, BC Women's Hospital, Vancouver, BC, Canada
| | - Sabrina Luke
- Women's Health Research Institute, BC Women's Hospital, Vancouver, BC, Canada
- Research and Surveillance Group, Perinatal Services British Columbia, Vancouver, BC, Canada
| | - Michelle Dittrick
- Department of Pathology and Laboratory Medicine, BC Children's and Women's Hospital, Vancouver, BC, Canada
| | - Victoria Higgins
- Clinical Biochemistry, DynaLIFE Medical Labs and Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada
| | - Khosrow Adeli
- Clinical Biochemistry, Pediatric Laboratory Medicine, The Hospital for Sick Children and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Hilary Vallance
- Department of Pathology and Laboratory Medicine, BC Children's and Women's Hospital, Vancouver, BC, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Benjamin Jung
- Clinical Biochemistry, Pediatric Laboratory Medicine, The Hospital for Sick Children and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Kent Dooley
- Clinical Biochemistry, LifeLabs Medical Laboratories, Victoria, BC, Canada
| | - Leanne Dahlgren-Scott
- Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, BC, Canada
| | - Wee-Shian Chan
- Department of Medicine, BC Women's Hospital and Division of General Internal Medicine, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
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2
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Doyle K, Bunch DR. Reference intervals: past, present, and future. Crit Rev Clin Lab Sci 2023; 60:466-482. [PMID: 37036018 DOI: 10.1080/10408363.2023.2196746] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 03/03/2023] [Accepted: 03/24/2023] [Indexed: 04/11/2023]
Abstract
Clinical laboratory test results alone are of little value in diagnosing, treating, and monitoring health conditions; as such, a clinically actionable cutoff or reference interval is required to provide context for result interpretation. Healthcare practitioners base their diagnoses, follow-up treatments, and subsequent testing on these reference points. However, they may not be aware of inherent limitations related to the definition and derivation of reference intervals. Laboratorians are responsible for providing the reference intervals they report with results. Yet, the establishment and verification of reference intervals using conventional direct methods are complicated by resource constraints or unique patient demographics. To facilitate standardized reference interval best practices, multiple global scientific societies are actively drafting guidelines and seeking funding to promote these initiatives. Numerous national and international multicenter collaborations demonstrate the ability to leverage combined resources to conduct large reference interval studies by direct methods. However, not all demographics are equally accessible. Novel indirect methods are attractive solutions that utilize computational methods to define reference distributions and reference intervals from mixed data sets of pathologic and non-pathologic patient test results. In an effort to make reference intervals more accurate and personalized, individual-based reference intervals are shown to be more useful than population-based reference intervals in detecting clinically significant analyte changes in a patient that might otherwise go unrecognized when using wider, population-based reference intervals. Additionally, continuous reference intervals can provide more accurate ranges as compared to age-based partitions for individuals that are near the ends of the age partition. The advantages and disadvantages of different reference interval approaches as well as the advancement of non-conventional reference interval studies are discussed in this review.
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Affiliation(s)
- Kelly Doyle
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Dustin R Bunch
- Nationwide Children's Hospital & College of Medicine, The Ohio State University, Columbus, OH, USA
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3
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Bohn MK, Nichols M, Yang L, Bhayana V, Macri J, Adeli K. Pediatric Reference Value Profiling of Essential Trace and Toxic Elements in Healthy Children and Adolescents Using High-Resolution and Triple Quadrupole Inductively Coupled Plasma Mass Spectrometry. J Appl Lab Med 2023:7174055. [PMID: 37207688 DOI: 10.1093/jalm/jfad019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 03/07/2023] [Indexed: 05/21/2023]
Abstract
BACKGROUND Assessment of trace and toxic element status is important for the diagnosis and monitoring of several pediatric conditions. Elemental deficiency and toxicity have serious implications, particularly in pediatrics wherein risk is higher. Pediatric reference intervals (RIs) for trace elements and normal exposure limits for toxic elements are lacking on modern analytical systems. Herein, reference values were established for 13 plasma and 22 whole blood trace elements in the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) cohort of healthy children and adolescents. METHODS Approximately 320 healthy children and adolescents were recruited with informed consent. Trace elements were measured in whole blood and plasma samples using 2 technologies: (a) triple quadrupole inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) (n = 172) and (b) high-resolution sector field ICPMS (HR-SF-ICPMS) (n =161). RIs and normal exposure limits were then established according to Clinical and Laboratory Standards Institute guidelines. RESULTS Of all elements assessed, none required sex partitioning and 8 required age partitioning (e.g., copper, manganese, and cadmium). Reference value distributions determined via ICP-MS/MS and HR-SF-ICPMS demonstrated excellent concordance, with few exceptions (e.g., molybdenum, cobalt, and nickel). CONCLUSIONS These data represent the first study wherein pediatric RIs and normal exposure limits were derived simultaneously on 2 different clinically validated MS platforms which provide urgently needed data to inform clinical decision-making for trace elements in pediatrics. Study findings suggest some trace elements require age-specific consideration for appropriate interpretation. Highly concordant observations across the 2 analytical methods also demonstrate the comparability and reliability of results obtained on both platforms.
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Affiliation(s)
- Mary Kathryn Bohn
- CALIPER Program, Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Matthew Nichols
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
| | - Liju Yang
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
| | - Vipin Bhayana
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
| | - Joseph Macri
- Department of Pathology and Molecular Medicine, Hamilton Health Sciences Centre, Hamilton, ON, Canada
| | - Khosrow Adeli
- CALIPER Program, Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
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4
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Ghazizadeh H, Kathryn Bohn M, Esmaily H, Boskabadi M, Mohammadi-Bajgiran M, Farahani E, Boshtam M, Mohammadifard N, Sarrafzadegan N, Adeli K, Ghayour-Mobarhan M. Comparison of reference intervals for biochemical and hematology markers derived by direct and indirect procedures based on the Isfahan cohort study. Clin Biochem 2023; 116:79-86. [PMID: 37030657 DOI: 10.1016/j.clinbiochem.2023.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 04/03/2023] [Accepted: 04/04/2023] [Indexed: 04/10/2023]
Abstract
INTRODUCTION Indirect methods for reference interval (RI) establishment apply statistical techniques to generate RIs for test result interpretation using stored laboratory data. They present unique advantages relative to traditional direct approaches such as fewer resource requirements; however, there is debate regarding their performance. Herein, we aimed to compare indirect and direct approaches for RI establishment by harnessing data from the Isfahan Cohort Study (ICS). This cohort includes both healthy individuals and those with a history of disease, enabling a direct comparison. METHODS Participants were recruited as part of ICS, including 6504 adults aged 34 years and older. Sociodemographic characteristics, anthropometry, blood pressure, various biochemical indices, and hematology parameters were collected. The refineR method was used to establish indirect RIs (before applying exclusion criteria). Direct RIs were calculated using nonparametric methods per CLSI EP28-A3 guidelines (after applying exclusion criteria). Bias ratios were calculated for each parameter to assess significant differences in estimations. RESULTS Direct and indirect RI estimations for most hematological and biochemical parameters were comparable. Statistically significant bias ratios between methods were observed for the upper limits of total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), hemoglobin (female), and platelet count as well as the lower limits of mean corpuscular hemoglobin (female), mean corpuscular volume, hemoglobin, and hematocrit (female). CONCLUSION Data presented indicate RIs derived from direct and indirect approaches are similar, but not identical. Further work should focus on the clinical significance of such differences as well as the investigation of necessary data-cleaning criteria before indirect method application.
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Affiliation(s)
- Hamideh Ghazizadeh
- CALIPER Program, Division of Clinical Biochemistry, Pediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, ON, Canada; International UNESCO Center for Health-Related Basic Sciences and Human Nutrition, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mary Kathryn Bohn
- CALIPER Program, Division of Clinical Biochemistry, Pediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, ON, Canada; Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Habibollah Esmaily
- Social Determinants of Health Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; Department of Biostatistics, School of Health, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mostafa Boskabadi
- Department of Biostatistics, School of Health, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Maryam Mohammadi-Bajgiran
- International UNESCO Center for Health-Related Basic Sciences and Human Nutrition, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Elina Farahani
- CALIPER Program, Division of Clinical Biochemistry, Pediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, ON, Canada; Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Maryam Boshtam
- Heart Failure Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Noushin Mohammadifard
- Interventional Cardiology Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Nizal Sarrafzadegan
- Isfahan Cardiovascular Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran.
| | - Khosrow Adeli
- CALIPER Program, Division of Clinical Biochemistry, Pediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, ON, Canada; Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, ON, Canada.
| | - Majid Ghayour-Mobarhan
- International UNESCO Center for Health-Related Basic Sciences and Human Nutrition, Mashhad University of Medical Sciences, Mashhad, Iran.
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5
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Haeckel R, Ammer T, Wosniok W, Krebs A, Torge A, Özcürümez M, Bertram A. Age-and sex-specific reference intervals of total cholesterol, LDL cholesterol, HDL cholesterol and non-HDL cholesterol. Comparison of two algorithms for the indirect estimation of reference intervals. J LAB MED 2023. [DOI: 10.1515/labmed-2022-0147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023] Open
Abstract
Abstract
Objectives
Reference intervals of total cholesterol concentrations in plasma and of their fractions low-density lipoprotein (LDL)-, high-density lipoprotein (HDL)-and non-HDL concentrations are seldom studied with respect to the relevance of age and sex. Therefore, the effect of age and sex on the reference intervals was reinvestigated with 2 indirect procedures.
Methods
As an indirect approach, the truncated minimum chi-square method was applied. All analyses were performed by computer programs available. The script published on the homepage of the German Society of Clinical Chemistry and Laboratory Medicine (DGKL) allows to derive a continuous age dependency of reference intervals together with their confidence and equivalence limits. The results of this approach were compared with those obtained by an indirect method developed more recently, the refineR algorithm.
Results
In the present study, the upper reference limits of total cholesterol varied from 5.1 to 7.8 mmol/L (197–302 mg/dL) depending on various biological variables (as age, sex, inpatients versus outpatients). These upper limits increased with age. Differences between sexes can be neglected except for the age above 80 years. The pattern of reference limits of LDL cholesterol and non-HDL cholesterol paralleled those of total cholesterol. The reference limits of HDL cholesterol were higher in women than in men but were independent of age.
Conclusions
Reference limits for the concentrations of total cholesterol and their fractions LDL-, HDL-and non-HDL concentrations should be stratified for age and sex.
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Affiliation(s)
- Rainer Haeckel
- Bremer Zentrum für Laboratoriumsmedizin, Klinikum Bremen Mitte , Bremen , Germany
| | - Tatjana Ammer
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Chair of Medical Informatics , Erlangen , Germany
- Roche Diagnostics GmbH , Penzberg , Germany
| | - Werner Wosniok
- Institut für Statistik, Universität Bremen , Bremen , Germany
| | | | - Antje Torge
- Institut für Klinische Chemie, Universitätsklinikum Schleswig-Holstein , Kiel , Germany
| | - Mustafa Özcürümez
- Universitätsklinikum Knappschaftskrankenhaus Bochum, Sektion Labormedizin der Medizinischen Klinik , Bochum , Germany
| | - Alexander Bertram
- Amedes MVZ wagnerstibbe für Laboratoriumsmedizin, Hämostaseologie, Humangenetik und Mikrobiologie , Hannover , Germany
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6
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Kang T, Yoo J, Jekarl DW, Chae H, Kim M, Park YJ, Oh EJ, Kim Y. Indirect Method for Estimation of Reference Intervals of Inflammatory Markers. Ann Lab Med 2023; 43:55-63. [PMID: 36045057 PMCID: PMC9467833 DOI: 10.3343/alm.2023.43.1.55] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 05/09/2022] [Accepted: 08/17/2022] [Indexed: 12/27/2022] Open
Abstract
Background The direct method for reference interval (RI) estimating is limited due to the requirement of resources, difficulties in defining a non-diseased population, or ethical problems in obtaining samples. We estimated the RI for inflammatory biomarkers using an indirect method (RII). Methods C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and presepsin (PSEP) data of patients visiting a single hospital were retrieved from April 2009 to April 2021. Right-skewed data were transformed using the Box-Cox transformation method. A mixed population of non-diseased and diseased distributions was assumed, followed by latent profile analysis for the two classes. The intersection point of the distribution curve was estimated as the RI. The influence of measurement size was evaluated as the ratio of abnormal values and adjustment (n×bandwidth) of the distribution curve. Results The RIs estimated by the proposed RII method (existing method) were as follows: CRP, 0-4.1 (0-4.7) mg/L; ESR, 0-10.2 (0-15) mm/hr and PSEP, 0-411 (0-300) pg/mL. Measurement sizes ≥2,500 showed stable results. An abnormal-to-normal value ratio of 0.5 showed the most accurate result for CRP. Adjustment values ≤5 or >5 were applicable for a measurement size <25,000 or ≥25,000, respectively. Conclusions The proposed RII method could provide additional information for RI verification or estimation with some limitations.
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Affiliation(s)
- Taewon Kang
- Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Jeaeun Yoo
- Department of Laboratory Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Dong Wook Jekarl
- Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.,Research and Development Institute for In Vitro Diagnostic Medical Devices, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Hyojin Chae
- Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Myungshin Kim
- Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Yeon-Joon Park
- Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Eun-Jee Oh
- Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.,Research and Development Institute for In Vitro Diagnostic Medical Devices, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Yonggoo Kim
- Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
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7
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Broecker-Preuss M, Arzideh F, Best J, Canbay A, Özçürümez M, Manka P. Comparison of age- and sex-dependent reference limits derived from distinct sources for metabolic measurands in basic liver diagnostics. ZEITSCHRIFT FUR GASTROENTEROLOGIE 2023; 61:50-59. [PMID: 36623543 DOI: 10.1055/a-1994-0809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Reference intervals for basic liver laboratory diagnostic rely on manufacturers' information, remaining unchanged for more than 20 years. This ignores known age and sex dependencies. METHODS We performed a retrospective cross-sectional study to compare the age-dependent distribution of flagged and non-flagged laboratory findings between reference limits from 3 distinct sources: manufacturer, published reference study, and the truncated maximum likelihood method applied on a cohort of inpatients aged 18-100 years. Discordance rates adjusted for the permissible analytical uncertainty are reported for serum levels of albumin (n= 150,550), alkaline phosphatase (n= 433,721), gamma-GT (n=580,012), AST (n= 510,620), and ALT (n= 704,546). RESULTS The number of flagged findings differed notably between reference intervals compared, except for alkaline phosphatase. AST and alkaline phosphatase increased with age in women. Overall discordance for AP, AST, and ALT remained below 10%, respectively, in both sexes. Albumin decreased with age which led to discordant flags in up to 22% in patients ≥70 years. GGT and ALT peaked in 50-59-year-old men with up to 23.5% and 22.8% discordant flags, respectively. CONCLUSION We assessed the impact of different reference limits on liver related laboratory results and found up to 25 % discordant flags. We suggest to further analyse the diagnostic and economic effects of reference limits adapted to the population of interest even for well-established basic liver diagnostics.
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Affiliation(s)
- Martina Broecker-Preuss
- Medizinische Klinik, Universitätsklinikum Knappschaftskrankenhaus Bochum, Ruhr-Universität Bochum, Bochum, Germany
| | - Farhad Arzideh
- Medizinische Klinik, Universitätsklinikum Knappschaftskrankenhaus Bochum, Ruhr-Universität Bochum, Bochum, Germany
| | - Jan Best
- Medizinische Klinik, Universitätsklinikum Knappschaftskrankenhaus Bochum, Ruhr-Universität Bochum, Bochum, Germany
| | - Ali Canbay
- Medizinische Klinik, Universitätsklinikum Knappschaftskrankenhaus Bochum, Ruhr-Universität Bochum, Bochum, Germany
| | - Mustafa Özçürümez
- Medizinische Klinik, Universitätsklinikum Knappschaftskrankenhaus Bochum, Ruhr-Universität Bochum, Bochum, Germany
| | - Paul Manka
- Medizinische Klinik, Universitätsklinikum Knappschaftskrankenhaus Bochum, Ruhr-Universität Bochum, Bochum, Germany
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8
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Müller J, Büchsel M, Timme M, App U, Miesbach W, Sachs UJ, Krause M, Scholz U. Reference Intervals in Coagulation Analysis. Hamostaseologie 2022; 42:381-389. [PMID: 36549290 DOI: 10.1055/a-1945-9490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Blood coagulation analysis is characterized by the application of a variety of materials, reagents, and analyzers for the determination of the same parameter, or analyte, by different laboratories worldwide. Accordingly, the application of common reference intervals, that, by definition, would represent a "range of values (of a certain analyte) that is deemed normal for a physiological measurement in healthy persons," is difficult to implement without harmonization of procedures. In fact, assay-specific reference intervals are usually established to allow for the discrimination of normal and abnormal values during evaluation of patient results. While such assay-specific reference intervals are often determined by assay manufacturers and subsequently adopted by customer laboratories, verification of transferred values is still mandatory to confirm applicability on site. The same is true for reference intervals that have been adopted from other laboratories, published information, or determined by indirect data mining approaches. In case transferable reference intervals are not available for a specific assay, a direct recruiting approach may or needs to be applied. In comparison to transferred reference interval verification, however, the direct recruiting approach requires a significantly higher number of well-defined samples to be collected and analyzed. In the present review, we aim to give an overview on the above-mentioned aspects and procedures, also with respect to relevant standards, regulations, guidelines, but also challenges for both, assay manufacturers and coagulation laboratories.
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Affiliation(s)
- Jens Müller
- Institute of Experimental Hematology and Transfusion Medicine, University Hospital Bonn, Bonn, Germany
| | - Martin Büchsel
- Institute of Clinical Chemistry and Laboratory Medicine, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Michael Timme
- Siemens Healthcare Diagnostics Products GmbH, Marburg, Germany
| | - Urban App
- Siemens Healthcare GmbH, Eschborn, Germany
| | - Wolfgang Miesbach
- Medical Clinic 2, Institute of Transfusion Medicine, University Hospital Frankfurt, Frankfurt, Germany
| | - Ulrich J Sachs
- Department of Thrombosis and Hemostasis, Giessen University Hospital, Giessen, Germany.,Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University, Giessen, Germany
| | - Michael Krause
- Center of Hemostasis, MVZ Labor Dr. Reising-Ackermann und Kollegen, Leipzig, Germany
| | - Ute Scholz
- Center of Hemostasis, MVZ Labor Dr. Reising-Ackermann und Kollegen, Leipzig, Germany
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9
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Coskun A, Sandberg S, Unsal I, Serteser M, Aarsand AK. Personalized reference intervals: from theory to practice. Crit Rev Clin Lab Sci 2022; 59:501-516. [PMID: 35579539 DOI: 10.1080/10408363.2022.2070905] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Using laboratory test results for diagnosis and monitoring requires a reliable reference to which the results can be compared. Currently, most reference data is derived from the population, and patients in this context are considered members of a population group rather than individuals. However, such reference data has limitations when used as the reference for an individual. A patient's test results preferably should be compared with their own, individualized reference intervals (RI), i.e. a personalized RI (prRI).The prRI is based on the homeostatic model and can be calculated using an individual's previous test results obtained in a steady-state situation and estimates of analytical (CVA) and biological variation (BV). BV used to calculate the prRI can be obtained from the population (within-subject biological variation, CVI) or an individual's own data (within-person biological variation, CVP). Statistically, the prediction interval provides a useful tool to calculate the interval (i.e. prRI) for future observation based on previous measurements. With the development of information technology, the data of millions of patients is stored and processed in medical laboratories, allowing the implementation of personalized laboratory medicine. PrRI for each individual should be made available as part of the laboratory information system and should be continually updated as new test results become available.In this review, we summarize the limitations of population-based RI for the diagnosis and monitoring of disease, provide an outline of the prRI concept and different approaches to its determination, including statistical considerations for deriving prRI, and discuss aspects which must be further investigated prior to implementation of prRI in clinical practice.
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Affiliation(s)
- Abdurrahman Coskun
- Acibadem Labmed Clinical Laboratories, Istanbul, Turkey.,Department of Medical Biochemistry, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Sverre Sandberg
- Norwegian Organization for Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital, Bergen, Norway.,Norwegian Porphyria Centre and Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway.,Department of Global Health and Primary Care, Faculty of Medicine and Dentistry, University of Bergen, Bergen, Norway
| | - Ibrahim Unsal
- Acibadem Labmed Clinical Laboratories, Istanbul, Turkey
| | - Mustafa Serteser
- Acibadem Labmed Clinical Laboratories, Istanbul, Turkey.,Department of Medical Biochemistry, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Aasne K Aarsand
- Norwegian Organization for Quality Improvement of Laboratory Examinations (Noklus), Haraldsplass Deaconess Hospital, Bergen, Norway.,Norwegian Porphyria Centre and Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
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10
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Ammer T, Schützenmeister A, Prokosch HU, Zierk J, Rank CM, Rauh M. RIbench: A Proposed Benchmark for the Standardized Evaluation of Indirect Methods for Reference Interval Estimation. Clin Chem 2022; 68:1410-1424. [PMID: 36264679 DOI: 10.1093/clinchem/hvac142] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 07/12/2022] [Indexed: 11/14/2022]
Abstract
BACKGROUND Indirect methods leverage real-world data for the estimation of reference intervals. These constitute an active field of research, and several methods have been developed recently. So far, no standardized tool for evaluation and comparison of indirect methods exists. METHODS We provide RIbench, a benchmarking suite for quantitative evaluation of any existing or novel indirect method. The benchmark contains simulated test sets for 10 biomarkers mimicking routine measurements of a mixed distribution of non-pathological (reference) values and pathological values. The non-pathological distributions represent 4 common distribution types: normal, skewed, heavily skewed, and skewed-and-shifted. To identify strengths and weaknesses of indirect methods, test sets have varying sample sizes and pathological distributions differ in location, extent of overlap, and fraction. For performance evaluation, we use an overall benchmark score and sub-scores derived from absolute z-score deviations between estimated and true reference limits. We illustrate the application of RIbench by evaluating and comparing the Hoffmann method and 4 modern indirect methods -TML (Truncated-Maximum-Likelihood), kosmic, TMC (Truncated-Minimum-Chi-Square), and refineR- against one another and against a nonparametric direct method (n = 120). RESULTS For the modern indirect methods, pathological fraction and sample size had a strong influence on the results: With a pathological fraction up to 20% and a minimum sample size of 5000, most methods achieved results comparable or superior to the direct method. CONCLUSIONS We present RIbench, an open-source R-package, for the systematic evaluation of existing and novel indirect methods. RIbench can serve as a tool for enhancement of indirect methods, improving the estimation of reference intervals.
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Affiliation(s)
- Tatjana Ammer
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Chair of Medical Informatics, Erlangen, Germany.,Roche Diagnostics GmbH, Biostatistics & Data Science, Penzberg, Germany
| | | | - Hans-Ulrich Prokosch
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Chair of Medical Informatics, Erlangen, Germany
| | - Jakob Zierk
- Universitätsklinikum Erlangen, Department of Pediatrics and Adolescent Medicine, Erlangen, Germany.,Universitätsklinikum Erlangen, Center of Medical Information and Communication Technology, Erlangen, Germany
| | | | - Manfred Rauh
- Universitätsklinikum Erlangen, Department of Pediatrics and Adolescent Medicine, Erlangen, Germany
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11
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Kim T, Choi H, Lee SM. Parametric and non-parametric estimation of reference intervals for routine laboratory tests: an analysis of health check-up data for 260 889 young men in the South Korean military. BMJ Open 2022; 12:e062617. [PMID: 35879016 PMCID: PMC9328105 DOI: 10.1136/bmjopen-2022-062617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 07/04/2022] [Indexed: 11/03/2022] Open
Abstract
OBJECTIVES Determination of reference intervals (RIs) using big data faces several obstacles due to heterogeneity in analysers, period and ethnicity. The present study aimed to establish the RIs for routine common blood count (CBC) and biochemistry laboratory tests in homogeneous, healthy, male Korean soldiers in their 20s using a large health check-up data set, comparing parametric and non-parametric estimation. DESIGN A multicentre, cross-sectional study. SETTING Seven armed forces hospitals in South Korea. PARTICIPANTS A total of 609 649 men underwent health examination when promoted to corporal between January 2015 and September 2021. 260 889 eligible individuals aged 20-25 were included in the analysis. MAIN OUTCOMES AND MEASURES The RIs were established by parametric and non-parametric methods. In the parametric approach, maximum likelihood estimation was applied to measure the Box-Cox transformation parameter and the values at the 2.5th and 97.5th percentiles were recalculated. The non-parametric approach adopted the Tukey's exclusion test and the values at the 2.5th and 97.5th percentiles were obtained. Classification by body mass index was also performed. RESULTS The obtained RIs for haematology parameters were comparable between devices. If the values followed a Gaussian distribution, parametric and non-parametric methods were well matched for haematology and biochemical markers. When the values were right-skewed, the upper limits were higher with parametric than with non-parametric methods. Participants with obesity showed higher RIs for CBC, some liver function tests and some lipid profiles than participants without obesity. CONCLUSIONS Using data from healthy, male Korean soldiers in their 20s, we proposed the RIs for CBC and biochemical parameters, comparing parametric and non-parametric estimation. As such approaches based on large data sets become more prevalent, further studies are needed to discriminate eligible individuals and determine RIs in an extrapolated sample.
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Affiliation(s)
- Taeyun Kim
- Internal Medicine, The Armed Forces Goyang Hospital, Goyang, Republic of Korea
| | - Hyunji Choi
- Laboratory Medicine, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea
- Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Gyeongnam, Republic of Korea
| | - Sun Min Lee
- Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Gyeongnam, Republic of Korea
- Laboratory Medicine, Pusan National University School of Medicine, Busan, Republic of Korea
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12
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Martinez-Sanchez L, Cobbaert CM, Noordam R, Brouwer N, Blanco-Grau A, Villena-Ortiz Y, Thelen M, Ferrer-Costa R, Casis E, Rodríguez-Frias F, den Elzen WPJ. Indirect determination of biochemistry reference intervals using outpatient data. PLoS One 2022; 17:e0268522. [PMID: 35588100 PMCID: PMC9119462 DOI: 10.1371/journal.pone.0268522] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 05/02/2022] [Indexed: 12/22/2022] Open
Abstract
The aim of this study was to determine reference intervals in an outpatient population from Vall d'Hebron laboratory using an indirect approach previously described in a Dutch population (NUMBER project). We used anonymized test results from individuals visiting general practitioners and analysed during 2018. Analytical quality was assured by EQA performance, daily average monitoring and by assessing longitudinal accuracy between 2018 and 2020 (using trueness verifiers from Dutch EQA). Per test, outliers by biochemically related tests were excluded, data were transformed to a normal distribution (if necessary) and means and standard deviations were calculated, stratified by age and sex. In addition, the reference limit estimator method was also used to calculate reference intervals using the same dataset. Finally, for standardized tests reference intervals obtained were compared with the published NUMBER results. Reference intervals were calculated using data from 509,408 clinical requests. For biochemical tests following a normal distribution, similar reference intervals were found between Vall d'Hebron and the Dutch study. For creatinine and urea, reference intervals increased with age in both populations. The upper limits of Gamma-glutamyl transferase were markedly higher in the Dutch study compared to Vall d'Hebron results. Creatine kinase and uric acid reference intervals were higher in both populations compared to conventional reference intervals. Medical test results following a normal distribution showed comparable and consistent reference intervals between studies. Therefore a simple indirect method is a feasible and cost-efficient approach for calculating reference intervals. Yet, for generating standardized calculated reference intervals that are traceable to higher order materials and methods, efforts should also focus on test standardization and bias assessment using commutable trueness verifiers.
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Affiliation(s)
- Luisa Martinez-Sanchez
- Clinical Laboratories, Biochemistry Department, Vall d’Hebron University Hospital, Barcelona, Spain
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Centre, Leiden, The Netherlands
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Christa M. Cobbaert
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Centre, Leiden, The Netherlands
| | - Raymond Noordam
- Department of Internal Medicine, Section of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, The Netherlands
| | - Nannette Brouwer
- Diagnost-IQ, Expert Centre for Clinical Chemistry, Purmerend, The Netherlands
| | - Albert Blanco-Grau
- Clinical Laboratories, Biochemistry Department, Vall d’Hebron University Hospital, Barcelona, Spain
| | - Yolanda Villena-Ortiz
- Clinical Laboratories, Biochemistry Department, Vall d’Hebron University Hospital, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Marc Thelen
- Laboratory for Clinical Chemistry and Hematology, Amphia, Breda, The Netherlands
- Stichting Kwaliteitsbewaking Medische Laboratoriumdiagnostiek, Nijmegen, The Netherlands
- Department of Laboratory Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Roser Ferrer-Costa
- Clinical Laboratories, Biochemistry Department, Vall d’Hebron University Hospital, Barcelona, Spain
| | - Ernesto Casis
- Clinical Laboratories, Biochemistry Department, Vall d’Hebron University Hospital, Barcelona, Spain
| | - Francisco Rodríguez-Frias
- Clinical Laboratories, Biochemistry Department, Vall d’Hebron University Hospital, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Wendy P. J. den Elzen
- Clinical Laboratories, Biochemistry Department, Vall d’Hebron University Hospital, Barcelona, Spain
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Centre, Leiden, The Netherlands
- Atalmedial Diagnostics Centre, Amsterdam, The Netherlands
- Department of Clinical Chemistry, Amsterdam Public Health research institute, Amsterdam UMC, Amsterdam, The Netherlands
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13
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Tan RZ, Markus C, Vasikaran S, Loh TP. Comparison of 8 methods for univariate statistical exclusion of pathological subpopulations for indirect reference intervals and biological variation studies. Clin Biochem 2022; 103:16-24. [PMID: 35181292 DOI: 10.1016/j.clinbiochem.2022.02.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 01/22/2022] [Accepted: 02/11/2022] [Indexed: 01/06/2023]
Abstract
BACKGROUND Indirect reference intervals and biological variation studies heavily rely on statistical methods to separate pathological and non-pathological subpopulations within the same dataset. In recognition of this, we compare the performance of eight univariate statistical methods for identification and exclusion of values originating from pathological subpopulations. METHODS The eight approaches examined were: Tukey's rule with and without Box-Cox transformation; median absolute deviation; double median absolute deviation; Gaussian mixture models; van der Loo (Vdl) methods 1 and 2; and the Kosmic approach. Using four scenarios including lognormal distributions and varying the conditions through the number of pathological populations, central location, spread and proportion for a total of 256 simulated mixed populations. A performance criterion of ±0.05 fractional error from the true underlying lower and upper reference interval was chosen. RESULTS Overall, the Kosmic method was a standout with the highest number of scenarios lying within the acceptable error, followed by Vdl method 1 and Tukey's rule. Kosmic and Vdl method 1 appears to discriminate better the non-pathological reference population in the case of log-normal distributed data. When the proportion and spread of pathological subpopulations is high, the performance of statistical exclusion deteriorated considerably. DISCUSSIONS It is important that laboratories use a priori defined clinical criteria to minimise the proportion of pathological subpopulation in a dataset prior to analysis. The curated dataset should then be carefully examined so that the appropriate statistical method can be applied.
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Affiliation(s)
- Rui Zhen Tan
- Engineering Cluster, Singapore Institute of Technology, Singapore
| | - Corey Markus
- International Centre for Point-of-Care Testing, Flinders Health and Medical Research Institute, Flinders University
| | - Samuel Vasikaran
- Department of Clinical Biochemistry, PathWest-Royal Perth Hospital, Perth, Western Australia, Australia
| | - Tze Ping Loh
- Department of Laboratory Medicine, National University Hospital, Singapore.
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14
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Yang D, Su Z, Zhao M. Big data and reference intervals. Clin Chim Acta 2022; 527:23-32. [PMID: 34999059 DOI: 10.1016/j.cca.2022.01.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 12/29/2021] [Accepted: 01/03/2022] [Indexed: 12/12/2022]
Abstract
Although reference intervals (RIs) play an important role in clinical diagnosis, there remain significant differences with respect to race, gender, age and geographic location. Accordingly, the Clinical Laboratory Standards Institute (CLSI) EP28-A3c has recommended that clinical laboratories establish RIs appropriate to their subject population. Unfortunately, the traditional and direct approach to establish RIs relies on the recruitment of a sufficient number of healthy individuals of various age groups, collection and testing of large numbers of specimens and accurate data interpretation. The advent of the big data era has, however, created a unique opportunity to "mine" laboratory information. Unfortunately, this indirect method lacks standardization, consensus support and CLSI guidance. In this review we provide a historical perspective, comprehensively assess data processing and statistical methods, and post-verification analysis to validate this big data approach in establishing laboratory specific RIs.
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Affiliation(s)
- Dan Yang
- National Clinical Research Center for Laboratory Medicine, The First Affiliated Hospital of China Medical University, Shenyang, PR China; Department of Laboratory Medicine, The First Affiliated Hospital of China Medical University, Shenyang, PR China; Units of Medical Laboratory, Chinese Academy of Medical Sciences, PR China
| | - Zihan Su
- National Clinical Research Center for Laboratory Medicine, The First Affiliated Hospital of China Medical University, Shenyang, PR China; Department of Laboratory Medicine, The First Affiliated Hospital of China Medical University, Shenyang, PR China; Units of Medical Laboratory, Chinese Academy of Medical Sciences, PR China
| | - Min Zhao
- National Clinical Research Center for Laboratory Medicine, The First Affiliated Hospital of China Medical University, Shenyang, PR China; Department of Laboratory Medicine, The First Affiliated Hospital of China Medical University, Shenyang, PR China; Units of Medical Laboratory, Chinese Academy of Medical Sciences, PR China.
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15
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Bracho FJ. Reference intervals of automated reticulocyte count and immature reticulocyte fraction in a pediatric population. Int J Lab Hematol 2021; 44:461-467. [PMID: 34859588 DOI: 10.1111/ijlh.13776] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 11/10/2021] [Accepted: 11/12/2021] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Reticulocytes are erythroid precursors that develop into mature erythrocytes, and they are an important tool to assess erythropoietic activity, as their count indicates the balance between the cells released from the bone marrow, their stage of maturity, and their rate of development into mature erythrocytes. Considering the described biological variability of the absolute reticulocyte count (ARC) and the immature reticulocyte fraction (IRF) and the limited information available on these hematological parameters in children, this study determined the reference intervals (RIs) of these parameters in a healthy pediatric population. METHODS A retrospective, observational, and analytical study was designed to establish RIs for the ARC and the IRF according to age and sex. An indirect sampling method was applied to a mixed database of complete blood counts from children aged 2 months to 18 years, using the truncated maximum likelihood indirect method for reference interval estimation. Percentiles were calculated to obtain bimodal RIs. RESULTS From a total of 190,812 samples, 6,814 were selected. Gender stratification was not necessary for the ARC and the IRF but they required partitioning into six and two age groups, respectively. CONCLUSION This study determined, by an indirect sampling method, RIs for the ARC and the IRF in a pediatric population according to age and sex.
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16
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Higgins V, Cheng PL, Selvaratnam R, Brinc D. Optimizing Measurement and Interpretation of the G6PD/Hb Ratio. J Appl Lab Med 2021; 6:1251-1263. [PMID: 33755132 DOI: 10.1093/jalm/jfab008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 01/25/2021] [Indexed: 11/12/2022]
Abstract
BACKGROUND Glucose-6-phosphate dehydrogenase (G6PD)/hemoglobin (Hb) ratio helps detect G6PD deficiency, an X-linked disorder that can be asymptomatic or cause acute hemolytic anemia and chronic hemolysis. We investigated preanalytical, analytical, and postanalytical aspects to optimize G6PD/Hb measurement and interpretation. METHODS G6PD was measured with the Pointe Scientific assay and Hb with Drabkin's reagent on Alinity c® (Abbott Diagnostics). Stability of G6PD/Hb was assessed after 7 and 14 days while stored at 2-8 °C. Stability of hemolysate prepared for G6PD analysis was assessed using QC and patient samples up to 4 h at room temperature or 2-8 °C. Analytical performance specifications including precision, method comparison, linearity, LOQ, and carry-over were established for the enzymatic reaction of G6PD and spectrophotometric reading of Hb. G6PD/Hb reference interval and cut-offs were established indirectly using truncated maximum likelihood method (TML) using retrospective data (n = 4715 patient data points). RESULTS Samples were stable after 7 days at 2-8°C, unless grossly hemolyzed. Hemolysate prepared for G6PD measurement remained stable for up to 4 h for QC at room temperature and 2-8°C, but up to 30 min-1 h at room temperature and 1-2 h at 2-8 °C for patient samples. Precision, linearity, LOQ, and carryover were acceptable. G6PD/Hb cut-offs were <3.3, ≥3.3, 3.3-8.9, and ≥8.9 U/g Hb for deficient males/females, normal males, intermediate females, and normal females, respectively. CONCLUSIONS In vitro hemolysis and delayed hemolysate analysis significantly reduce G6PD/Hb stability. QC material cannot detect the impact of delayed hemolysate analysis. These findings were foundational for optimizing G6PD/Hb protocols for a new platform and establishing laboratory-specific G6PD/Hb cut-offs.
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Affiliation(s)
- Victoria Higgins
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Pow Lee Cheng
- Department of Laboratory Medicine, University Health Network, Toronto, ON, Canada
| | - Rajeevan Selvaratnam
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, ON, Canada.,Department of Laboratory Medicine, University Health Network, Toronto, ON, Canada
| | - Davor Brinc
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, ON, Canada.,Department of Laboratory Medicine, University Health Network, Toronto, ON, Canada
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17
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Ammer T, Schützenmeister A, Prokosch HU, Rauh M, Rank CM, Zierk J. refineR: A Novel Algorithm for Reference Interval Estimation from Real-World Data. Sci Rep 2021; 11:16023. [PMID: 34362961 PMCID: PMC8346497 DOI: 10.1038/s41598-021-95301-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 07/21/2021] [Indexed: 01/02/2023] Open
Abstract
Reference intervals are essential for the interpretation of laboratory test results in medicine. We propose a novel indirect approach to estimate reference intervals from real-world data as an alternative to direct methods, which require samples from healthy individuals. The presented refineR algorithm separates the non-pathological distribution from the pathological distribution of observed test results using an inverse approach and identifies the model that best explains the non-pathological distribution. To evaluate its performance, we simulated test results from six common laboratory analytes with a varying location and fraction of pathological test results. Estimated reference intervals were compared to the ground truth, an alternative indirect method (kosmic), and the direct method (N = 120 and N = 400 samples). Overall, refineR achieved the lowest mean percentage error of all methods (2.77%). Analyzing the amount of reference intervals within ± 1 total error deviation from the ground truth, refineR (82.5%) was inferior to the direct method with N = 400 samples (90.1%), but outperformed kosmic (70.8%) and the direct method with N = 120 (67.4%). Additionally, reference intervals estimated from pediatric data were comparable to published direct method studies. In conclusion, the refineR algorithm enables precise estimation of reference intervals from real-world data and represents a viable complement to the direct method.
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Affiliation(s)
- Tatjana Ammer
- Chair of Medical Informatics, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany. .,Roche Diagnostics GmbH, Penzberg, Germany.
| | | | - Hans-Ulrich Prokosch
- Chair of Medical Informatics, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Manfred Rauh
- Department of Pediatrics and Adolescent Medicine, University Hospital Erlangen, Erlangen, Germany
| | | | - Jakob Zierk
- Department of Pediatrics and Adolescent Medicine, University Hospital Erlangen, Erlangen, Germany.,Center of Medical Information and Communication Technology, University Hospital Erlangen, Erlangen, Germany
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18
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Signalment and Clinical Data of Cats with Exocrine Pancreatic Insufficiency Diagnosed Using Feline Trypsin-like Immunoreactivity in Routine Diagnostics. Vet Sci 2021; 8:vetsci8080155. [PMID: 34437477 PMCID: PMC8402856 DOI: 10.3390/vetsci8080155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/21/2021] [Accepted: 07/30/2021] [Indexed: 11/16/2022] Open
Abstract
Serum feline trypsin-like immunoreactivity (fTLI) is commonly used to diagnose feline exocrine pancreatic insufficiency (EPI). This study aimed to describe signalment and clinical data of cats with EPI. Determination of TLI was performed using an in-house ELISA; the reference interval was defined using a Reference Limit Estimator. Groups were formed from 4813 cats (2019-2020), based on their fTLI concentration: 1 (<8 µg/L; decreased; n = 275), 2 (8-88 µg/L; reference interval; n = 4256), and 3 (>88 µg/L; increased; n = 282). Males and Domestic Shorthairs were most common in all groups. Group 3 had the highest (13 years), and group 1 had the lowest (9 years), median age. Clinical information was available for 200 cats (decreased fTLI: n = 87, lower reference interval (8-12 µg/L): n = 113). Treatment response was observed in 83% (decreased fTLI) and 66% (lower reference interval). EPI cats displayed weight loss (69%), diarrhoea (68%), vomiting (41%), anorexia (39%), poor hair coat (35%), lethargy (33%), and/or polyphagia (21%). The lower the serum fTLI concentration, the more often good treatment response was reported (p = 0.022) but there were no statistically significant clinical signs. In conclusion, fTLI is a helpful parameter to diagnose EPI but predicting treatment response based on signalment or clinical signs is not possible.
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19
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Ozarda Y, Ichihara K, Jones G, Streichert T, Ahmadian R. Comparison of reference intervals derived by direct and indirect methods based on compatible datasets obtained in Turkey. Clin Chim Acta 2021; 520:186-195. [PMID: 34081933 DOI: 10.1016/j.cca.2021.05.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 04/30/2021] [Accepted: 05/26/2021] [Indexed: 11/17/2022]
Abstract
BACKGROUND Indirect derivation of reference intervals (RIs) from the laboratory information system (LIS) has been recently pursued. We aimed at evaluating the accuracy of indirectly predicted RIs compared to the RIs established directly from healthy subjects in the nationwide RI study in Turkey, targeting 25 major chemistry analytes. METHODS LIS data were retrieved from the laboratory that performed measurements for the direct study. They were cleaned by limiting to outpatients with age 18-65 years, and by allowing only one record per year per patient. Evaluated were four indirect methods of univariate approach: Hoffmann, Bhattacharya, Arzideh, and Wosniok methods. Power transformation of the LIS dataset was performed either using the power (λ) reported by the IFCC global RI study (the first two methods) or using a λ predicted (the last two). RESULTS Compared to the direct study dataset, the LIS dataset showed a variable degree of alterations in peak location and shape. Consequently, lower-side peak-shifts observed in sodium, albumin, etc. led to lowered RI limits, whereas higher-side peak-shift observed in triglyceride, low-density lipoprotein cholesterol, etc. led to raised RI limits. Overall, 72% (62-81) of the RI limits predicted by indirect methods showed significant biases from direct RIs. However, the biases observed in total cholesterol, lactic dehydrogenase, etc. were attributed to a higher-side age-bias in LIS dataset. After excluding them, the overall proportion of biased RIs was reduced to 47% (38-54). CONCLUSION To reduce prediction biases that remained after age adjustment, it is necessary to apply more rigorous data-cleaning before applying indirect methods.
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Affiliation(s)
- Yesim Ozarda
- Department of Medical Biochemistry, Istanbul Health and Technology University School of Medicine, Istanbul, Turkey.
| | - Kiyoshi Ichihara
- Faculty of Health Sciences, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Graham Jones
- Department of Chemical Pathology, SydPath, St Vincent's Hospital, Sydney, NSW, Australia; University of NSW, Sydney, NSW, Australia
| | - Thomas Streichert
- Institute for Clinical Chemistry, Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Robab Ahmadian
- Department of Statistics, Uludag University School of Medicine, Bursa, Turkey
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20
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Amodeo B, Schindler A, Schacht U, Wahl HG. Calculation of indirect reference intervals of plasma lipase activity of adults from existing laboratory data based on the Reference Limit Estimator integrated in the OPUS::L information system. J LAB MED 2021. [DOI: 10.1515/labmed-2021-0008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Objectives
Most laboratories have difficulties to determine their own reference intervals for the diagnostic evaluation of patient results by direct methods. Therefore, data is often just taken from the literature or package inserts of the analytical tests.
Methods
The section on Reference Limits of the German Society for Clinical Chemistry and Laboratory Medicine (DGKL) first uploaded the Reference Limit Estimator (RLE) as an R-program with MS Excel-interface on the DGKL home page and now this tool is implemented in the commercial Laboratory Information System OPUS::L (OSM AG Essen, Germany). We used this OPUS::L “Population specific Reference Limits” tool online with our laboratory database. First calculations were done using the example of lipase.
Results
The manufacturer’s original reference interval for lipase 12–53 U/L (adults) was changed to age dependent upper reference limits of <41 U/L (<20 years), <60 U/L (20–80 years) and <70 U/L (>80 years).
Conclusions
By means of the OPUS::L “Population specific Reference Limits” tool we were able to establish our laborarotry specific reference interval for plasma lipase activity. The new reference limits helped to solve an old problem of implausible low elevated lipase values.
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Affiliation(s)
| | | | | | - Hans Günther Wahl
- Medizinisches Labor Wahl , Lüdenscheid , Germany
- Institute of Laboratory Medicine and Pathobiochemistry , Philipps University Marburg , UKGM Marburg GmbH , Marburg , Germany
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21
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Chauffaille MDL, Takihi IY, Prieto WH, Russo PDST, Sandes AF, Perazzio AB, Silva MCA, Gonçalves MV. New reference values for the old erythrocyte sedimentation rate. Int J Lab Hematol 2021; 43:O214-O217. [PMID: 33794065 DOI: 10.1111/ijlh.13523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 03/03/2021] [Accepted: 03/08/2021] [Indexed: 11/27/2022]
Affiliation(s)
| | | | | | | | - Alex F Sandes
- Division of Hematology, Fleury Group, São Paulo, Brazil
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22
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Özcürümez M, Arzideh F, Torge A, Figge A, Haeckel R, Streichert T. The influence of sampling time on indirect reference limits, decision limits, and the estimation of biological variation of random plasma glucose concentrations. J LAB MED 2021. [DOI: 10.1515/labmed-2020-0146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Objectives
Plasma glucose concentrations exhibit a pronounced daytime-dependent variation. The oscillations responsible for this are currently not considered in the determination of reference limits (RL) and decision limits.
Methods
We characterized the daily variation inherent in large-scale laboratory data from two different university hospitals (site 1 n=513,682, site 2 n=204,001). Continuous and distinct RL for daytime and night were estimated. Diurnal characteristics of glucose concentrations were further investigated by quantile regression analyses introducing age and cosinor-functions as predictors in the model.
Results
Diurnal variations expressed as amplitude/Midline Estimating Statistic of Rhythm (MESOR) ratio, averaged 7.7% (range 5.9–9.3%). The amplitude of glucose levels decreased with increasing concentrations. Between 06:00 and 10:00 h an average decrease of 4% has to be considered. Nocturnal glucose samples accounted for only 5% of the total amount but contributed to 19.5% of all findings over 11.1 mmol/L. Partitioning of RL between day and night is merely justified for the upper reference limit. The nocturnal upper RLs for both genders differed from those obtained during the day by 11.0 and 10.6% at site 1 and by 7.6 and 7.5% at site 2.
Conclusions
We conclude that indirect approaches to estimate upper RL of random plasma glucose concentrations require stratification concerning the time of sample collection.
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Affiliation(s)
- Mustafa Özcürümez
- Medizinische Klinik, Universitätsklinikum Knappschaftskrankenhaus Bochum , Bochum , Germany
| | - Farhad Arzideh
- Medizinische Klinik, Universitätsklinikum Knappschaftskrankenhaus Bochum , Bochum , Germany
| | - Antje Torge
- Institut für Klinische Chemie , Universitätsklinikum Schleswig-Holstein , Kiel , Germany
| | - Anja Figge
- Medizinische Klinik, Universitätsklinikum Knappschaftskrankenhaus Bochum , Bochum , Germany
| | - Rainer Haeckel
- Bremer Zentrum für Laboratoriumsmedizin, Klinikum Bremen Mitte , Bremen , Germany
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23
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Haeckel R, Wosniok W, Streichert T. Review of potentials and limitations of indirect approaches for estimating reference limits/intervals of quantitative procedures in laboratory medicine. J LAB MED 2021. [DOI: 10.1515/labmed-2020-0131] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Abstract
Reference intervals (RIs) can be determined by direct and indirect procedures. Both approaches identify a reference population from which the RIs are defined. The crucial difference between direct and indirect methods is that direct methods select particular individuals after individual anamnesis and medical examination have confirmed the absence of pathological conditions. These individuals form a reference subpopulation. Indirect methods select a reference subpopulation in which the individuals are not identified. They isolate a reference population from a mixed population of patients with pathological and non-pathological conditions by statistical reasoning.
At present, the direct procedure internationally recommended is the “gold standard”. It has, however, the disadvantage of high expenses which cannot easily be afforded by most medical laboratories. Therefore, laboratories adopt RIs established by direct methods from external sources requiring a high responsibility for transference problems which are usually neglected by most laboratories. These difficulties can be overcome by indirect procedures which can easily be performed by most laboratories without causing economic problems.
The present review focuses on indirect approaches. Various procedures are presented with their benefits and limitations. Preliminary simulation studies indicate that more recently developed concepts are superior to older approaches.
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Affiliation(s)
- Rainer Haeckel
- Bremer Zentrum für Laboratoriumsmedizin, Klinikum Bremen Mitte , Bremen , Germany
| | - Werner Wosniok
- Institut für Statistik, Universität Bremen , Bremen , Germany
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Abstract
Abstract
The indirect approach to defining reference intervals operates ‘a posteriori’, on stored laboratory data. It relies on being able to separate healthy and diseased populations using one or both of clinical techniques or statistical techniques. These techniques are also fundamental in a priori, direct reference interval approaches. The clinical techniques rely on using clinical data that is stored either in the electronic health record or within the laboratory database, to exclude patients with possible disease. It depends on the investigators understanding of the data and the pathological impacts on tests. The statistical technique relies on identifying a dominant, apparently healthy, typically Gaussian distribution, which is unaffected by the overlapping populations with higher (or lower) results. It depends on having large databases to give confidence in the extrapolation of the narrow portion of overall distribution representing unaffected individuals. The statistical issues involved can be complex, and can result in unintended bias, particularly when the impacts of disease and the physiological variations in the data are under appreciated.
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Affiliation(s)
- Kenneth A. Sikaris
- Department of Biochemistry , Melbourne Pathology , Collingwood , VIC , Australia
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Affiliation(s)
- Rainer Haeckel
- Bremer Zentrum für Laboratoriumsmedizin , Klinikum Bremen Mitte , 28305 Bremen , Germany
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Martinez-Sanchez L, Marques-Garcia F, Ozarda Y, Blanco A, Brouwer N, Canalias F, Cobbaert C, Thelen M, den Elzen W. Big data and reference intervals: rationale, current practices, harmonization and standardization prerequisites and future perspectives of indirect determination of reference intervals using routine data. ADVANCES IN LABORATORY MEDICINE 2021; 2:9-25. [PMID: 37359198 PMCID: PMC10197285 DOI: 10.1515/almed-2020-0034] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/24/2020] [Indexed: 06/28/2023]
Abstract
Reference intervals are commonly used as a decision-making tool. In this review, we provide an overview on "big data" and reference intervals, describing the rationale, current practices including statistical methods, essential prerequisites concerning data quality, including harmonization and standardization, and future perspectives of the indirect determination of reference intervals using routine laboratory data.
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Affiliation(s)
- Luisa Martinez-Sanchez
- Clinical Biochemistry Department, Vall d’Hebron University Hospital, Barcelona, Spain
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Centre, Leiden, The Netherlands
- Department de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | | | - Yesim Ozarda
- Department of Medical Biochemistry, Uludag University School of Medicine, Bursa, Turkey
| | - Albert Blanco
- Clinical Biochemistry Department, Vall d’Hebron University Hospital, Barcelona, Spain
| | - Nannette Brouwer
- Diagnost-IQ, Expert Centre for Clinical Chemistry, Purmerend, The Netherlands
| | - Francesca Canalias
- Laboratori de Referència d’Enzimologia Clínica, Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Christa Cobbaert
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Centre, Leiden, The Netherlands
| | - Marc Thelen
- Laboratory for Clinical Chemistry and Hematology, Amphia, Breda, The Netherlands
- Stichting Kwaliteitsbewaking Medische Laboratoriumdiagnostiek, Nijmegen, The Netherlands
| | - Wendy den Elzen
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Centre, Leiden, The Netherlands
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Serdar CC, Cihan M, Yücel D, Serdar MA. Sample size, power and effect size revisited: simplified and practical approaches in pre-clinical, clinical and laboratory studies. Biochem Med (Zagreb) 2021; 31:010502. [PMID: 33380887 PMCID: PMC7745163 DOI: 10.11613/bm.2021.010502] [Citation(s) in RCA: 333] [Impact Index Per Article: 111.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 11/12/2020] [Indexed: 12/14/2022] Open
Abstract
Calculating the sample size in scientific studies is one of the critical issues as regards the scientific contribution of the study. The sample size critically affects the hypothesis and the study design, and there is no straightforward way of calculating the effective sample size for reaching an accurate conclusion. Use of a statistically incorrect sample size may lead to inadequate results in both clinical and laboratory studies as well as resulting in time loss, cost, and ethical problems. This review holds two main aims. The first aim is to explain the importance of sample size and its relationship to effect size (ES) and statistical significance. The second aim is to assist researchers planning to perform sample size estimations by suggesting and elucidating available alternative software, guidelines and references that will serve different scientific purposes.
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Affiliation(s)
- Ceyhan Ceran Serdar
- Medical Biology and Genetics, Faculty of Medicine, Ankara Medipol University, Ankara, Turkey
| | - Murat Cihan
- Ordu University Training and Research Hospital, Ordu, Turkey
| | - Doğan Yücel
- Department of Medical Biochemistry, Lokman Hekim University School of Medicine, Ankara, Turkey
| | - Muhittin A Serdar
- Department of Medical Biochemistry, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
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Bohn MK, Adeli K. Application of the TML method to big data analytics and reference interval harmonization. J LAB MED 2021. [DOI: 10.1515/labmed-2020-0133] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Abstract
Significant variation in reported reference intervals across healthcare centers and networks for many well-standardized laboratory tests continues to exist, negatively impacting patient outcomes by increasing the risk of inappropriate and inconsistent test result interpretation. Reference interval harmonization has been limited by challenges associated with direct reference interval establishment as well as hesitancies to apply currently available indirect methodologies. The Truncated Maximum Likelihood (TML) method for indirect reference interval establishment developed by the German Society of Clinical Chemistry and Laboratory Medicine (DGKL) presents unique clinical and statistical advantages compared to traditional indirect methods (Hoffmann and Bhattacharya), increasing the feasibility of developing indirect reference intervals that are comparable to those determined using a direct a priori approach based on healthy reference populations. Here, we review the application of indirect methods, particularly the TML method, to reference interval harmonization and discuss their associated advantages and disadvantages. We also describe the CSCC Reference Interval Harmonization Working Group’s experience with the application of the TML method in harmonization of adult reference intervals in Canada.
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Affiliation(s)
- Mary Kathryn Bohn
- Molecular Medicine and Clinical Biochemistry , The Hospital for Sick Children, University of Toronto , Toronto , ON , Canada
| | - Khosrow Adeli
- Molecular Medicine and Clinical Biochemistry , The Hospital for Sick Children, University of Toronto , Toronto , ON , Canada
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Reference limits of high-sensitive cardiac troponin T indirectly estimated by a new approach applying data mining. A special example for measurands with a relatively high percentage of values at or below the detection limit. J LAB MED 2020. [DOI: 10.1515/labmed-2020-0063] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Abstract
A new model for the indirect estimation of reference limits (RLs) has been proposed recently and was coined TMC approach (truncated minimum chi-square estimation) which can be performed with R statistic. A spline function is applied to the RLs to get a continuous function if age is graphically presented vs. the RLs avoiding artificial “jumps” between different age groups. Most indirect models assume a power normal distribution and fail if this assumption is not fulfilled as e.g. if a relatively high percentage of measured values is below the detection limit and the data are distributed extremely skewed. This problem is handled by the TMC model. High-sensitive cardiac troponin T (hs cTnT) was chosen as an example. The hs cTnT concentration in serum or plasma is well accepted as a valuable marker in the diagnosis of acute myocardial infarction. Currently, the 99th percentile derived from a “healthy” subpopulation is the decision limit recommended by consensus groups. However, this decision limit is questioned by several authors for many reasons. In the present report, the 97.5th and the 99th percentile limits were reinvestigated by the TMC model with different subpopulations stratified according to age and sex and were finally compared to presently recommended decision limits. In summary, the generally recommended 99th percentile as a fixed decision limit should be reconsidered. It is suggested to apply more specific reference limits stratified for age and sex instead of a fixed decision limit.
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Ma C, Wang X, Wu J, Cheng X, Xia L, Xue F, Qiu L. Real-world big-data studies in laboratory medicine: Current status, application, and future considerations. Clin Biochem 2020; 84:21-30. [DOI: 10.1016/j.clinbiochem.2020.06.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/25/2020] [Accepted: 06/30/2020] [Indexed: 12/20/2022]
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Haeckel R, Wosniok W, Torge A, Junker R, Bertram A, Krebs A, Özcürümez M, Orth M, Streichert T. Age and sex dependent reference intervals for random plasma/serum glucose concentrations related to different sampling devices and determined by an indirect procedure with data mining. J LAB MED 2020. [DOI: 10.1515/labmed-2020-0064] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Abstract
The glucose concentration in plasma or serum is one of the most often requested analytical values in laboratory medicine. Whereas the analytical part of the glucose determination is well standardised, the standardisation of the pre-examination part (pre-analytical phase) is not sufficiently solved, yet. In view of the present controversial discussion regarding the most efficient prevention of pre-analytical glycolysis, the question arises whether the economical and logistic expenses for inhibiting glycolysis determining random glucose concentration are justified. In hospitals with adequate logistics (e.g. pneumatic tube systems for blood tubes) to guarantee a blood sample transport time of about 1 – 2 h, plasma or serum without prevention of glycolysis can be applied for random glucose concentrations if the reference limits are estimated by the laboratory. If such logistics are not available, especially in primary care services, either plasma or serum samples or whole blood in special tubes with anti-glycolytic additives may be sent to the laboratory.
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Affiliation(s)
- Rainer Haeckel
- Bremer Zentrum für Laboratoriumsmedizin, Klinikum Bremen Mitte , 28305 Bremen , Germany
| | - Werner Wosniok
- Institut für Statistik, Universität Bremen , Bremen , Germany
| | - Antje Torge
- Institut für Klinische Chemie, Universitätsklinikum Schleswig-Holstein , Kiel , Germany
| | - Ralf Junker
- Institut für Klinische Chemie, Universitätsklinikum Schleswig-Holstein , Kiel , Germany
| | - Alexander Bertram
- Amedes MVZ wagnerstibbe für Laboratoriumsmedizin, Hämostaseologie, Humangenetik und Mikrobiologie , Hannover , Germany
| | - Alexander Krebs
- MVZ Labor PD Dr. Volkmann und Kollegen , Karlsruhe , Germany
| | - Mustafa Özcürümez
- Universitätsklinikum Knappschaftskrankenhaus Bochum, Sektion Labormedizin der Medizinischen Klinik , Bochum , Germany
| | - Matthias Orth
- Institut für Laboratoriumsmedizin, Vinzenz von Paul Kliniken GmbH , Stuttgart , Germany
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Hermann W, Risch L, Grebhardt C, Nydegger UE, Sakem B, Imperiali M, Renz H, Risch M. Reference Intervals for Platelet Counts in the Elderly: Results from the Prospective SENIORLAB Study. J Clin Med 2020; 9:jcm9092856. [PMID: 32899382 PMCID: PMC7564319 DOI: 10.3390/jcm9092856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 08/27/2020] [Accepted: 09/01/2020] [Indexed: 01/08/2023] Open
Abstract
Currently, age- and sex-independent reference limits (RLs) are frequently used to interpret platelet counts in seniors. We aimed to define and validate reference intervals (RIs) for platelet counts within the framework of the prospective SENIORLAB study. Subjectively healthy Swiss individuals aged 60 years and older were prospectively included and followed for morbidity and mortality. Participants who had circumstances known to affect platelet counts were excluded. The obtained RIs were validated with indirect statistical methods. Frequencies of abnormal platelet counts in a population-based setting, including 41.5% of the entire age-specific population of the Principality of Liechtenstein, were compared by using age- and sex-independent RIs and the RLs obtained in the present study. For males (n = 542), 95% RIs for platelet counts were defined as follows: 150–300 × 109/L (60–69 years); 130–300 × 109/L (70–79 years); and 120–300 × 109/L (80 years and above). For females (n = 661), the consolidated age-independent 95% RI was 165–355 × 109/L. These RI values were validated by indirect RI determination of 51,687 (30,392 female/21,295 male) patients of the same age. Age- and sex-independent RIs exhibited imbalanced frequencies of abnormal platelet counts between the two sexes, which were corrected by introducing age- and sex-specific RLs. In conclusion, females have higher platelet counts than males. Whereas the upper RL for males remains constant, the lower RL decreases with age. We propose to abandon the practice of employing sex- and age-independent RL for platelet counts in the elderly.
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Affiliation(s)
- Wolfgang Hermann
- Faculty of medical sciences, Private Universität im Fürstentum Liechtenstein, Dorfstrasse 24, 9495 Triesen, Liechtenstein; (W.H.); (L.R.)
| | - Lorenz Risch
- Faculty of medical sciences, Private Universität im Fürstentum Liechtenstein, Dorfstrasse 24, 9495 Triesen, Liechtenstein; (W.H.); (L.R.)
- Labormedizinisches Zentrum Dr. Risch, Wuhrstrasse 14, 9490 Vaduz, Liechtenstein
- Center of Laboratory Medicine, University Institute of Clinical Chemistry, University of Bern, 3012 Bern, Switzerland
| | - Chris Grebhardt
- Faculty of Medicine, University of Basel, Klingelbergstrasse 61, 4056 Basel, Switzerland;
| | - Urs E. Nydegger
- Labormedizinisches zentrum Dr. Risch, Waldeggstrasse 37, 3097 Liebefeld, Switzerland; (U.E.N.); (B.S.)
| | - Benjamin Sakem
- Labormedizinisches zentrum Dr. Risch, Waldeggstrasse 37, 3097 Liebefeld, Switzerland; (U.E.N.); (B.S.)
| | - Mauro Imperiali
- Centro Medicina di Laboratorio Dr. Risch, Via Arbostra 2, 6963 Pregassona, Switzerland;
| | - Harald Renz
- Institute of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Philipps University Marburg, University Hospital Giessen and Marburg, Baldingerstraße, 35043 Marburg, Germany;
| | - Martin Risch
- Zentrallabor, Kantonsspital Graubünden, Loësstrasse 170, 7000 Chur, Switzerland
- Correspondence:
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Matsuo R, Yamazaki T, Suzuki M, Toyama H, Araki K. A random forest algorithm-based approach to capture latent decision variables and their cutoff values. J Biomed Inform 2020; 110:103548. [PMID: 32866626 DOI: 10.1016/j.jbi.2020.103548] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 08/21/2020] [Accepted: 08/25/2020] [Indexed: 11/18/2022]
Abstract
Although reference intervals (RIs) and clinical decision limits (CDLs) are vital laboratory information for supporting the interpretation of numerical clinical pathology results, there is evidence that RIs and CDLs vary in certain contexts as well as other evidence that RIs and CDLs are flawed. We propose a random forest algorithm-based exploration methodology by using phenotype transformation of independent variables in relation to dependent variables to capture latent decision variables and their cutoff values. We denote certain CDLs within the RIs estimated by an indirect method that affect some diagnostics or outcomes in the context of specific patients' conditions as latent CDLs. We then apply the proposed methodology to clinical laboratory data regarding bodily fluids, such as blood, urine at the admission of patients for the exploration of latent CDLs of hospital length of stay (HLOS) for each patients' condition identified by diseases of patients who undergoing surgeries. From the exploration results, we found that free Thyroxine (T4) above five unique cutoff values: 1.16 ng/dL, 1.19 ng/dL, 1.2 ng/dL, 1.23 ng/dL and 1.25 ng/dL for tachyarrhythmia predicted longer HLOS, though these cutoff values fall within the estimated RIs as well as the hospital-determined RIs. In addition to the evidence that higher free Thyroxine (T4) levels within the RIs have an association with the corresponding disease, on the whole, the cutoff values except 1.16 ng/dL tended to affect long HLOS with the significant differences. The cutoff values could be taken up for discussion among clinical experts whether it is meaningful to alert the risk of patients' conditions and the long HLOS at the admission of patients. If clinical experts appreciate its meaningfulness in clinical practice, the alerts could be embedded in electronic medical records for handling those risks at the admission of patients.
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Affiliation(s)
- Ryosuke Matsuo
- Faculty of Medicine, University of Miyazaki Hospital, 5200, Kihara, Kiyotake-cho, Miyazaki-shi, Miyazaki, 889-1692, Japan.
| | - Tomoyoshi Yamazaki
- Faculty of Medicine, University of Miyazaki Hospital, 5200, Kihara, Kiyotake-cho, Miyazaki-shi, Miyazaki, 889-1692, Japan.
| | - Muneou Suzuki
- Faculty of Medicine, University of Miyazaki Hospital, 5200, Kihara, Kiyotake-cho, Miyazaki-shi, Miyazaki, 889-1692, Japan.
| | - Hinako Toyama
- Institute of Medical Data Sciences, 1-10-2, Tsukushino, Abiko-shi, Chiba, 270-1164, Japan.
| | - Kenji Araki
- Faculty of Medicine, University of Miyazaki Hospital, 5200, Kihara, Kiyotake-cho, Miyazaki-shi, Miyazaki, 889-1692, Japan.
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Mokhtar KM. TSH continuous reference intervals by indirect methods: A Comparisons to Partitioned Reference Intervals. Clin Biochem 2020; 85:53-56. [PMID: 32795473 DOI: 10.1016/j.clinbiochem.2020.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/30/2020] [Accepted: 08/09/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To establish continuous reference intervals for TSH by data mining, using quantile regression with restricted cubic splines model. DESIGN AND METHOD TSH results (n=13,333) were collected for a four years period (between March 2015 and February 2020). After an exclusion step, TSH results (n=8838) were used to derive continuous reference intervals (i.e. 2.5th and 97.5th percentiles) spanning 18-90 years of age, using quantile regression with restricted cubic splines (RCS) model, then compared to age-partitioned reference intervals generated by Bhattacharya analysis. RESULTS Despite similar reference intervals to the Bhattacharya analysis, continuous reference intervals appeared to give a more accurate and consistent estimation of the upper reference limits (i.e.97.5thpercentiles) with complex age-related variations in serum TSH concentrations. CONCLUSION Our results suggest that quantile regression with RCS model appears to be a very useful tool available for clinical laboratories to establish local continuous TSH reference intervals.
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Lo Sasso B, Vidali M, Scazzone C, Agnello L, Ciaccio M. Reference interval by the indirect approach of serum thyrotropin (TSH) in a Mediterranean adult population and the association with age and gender. Clin Chem Lab Med 2020; 57:1587-1594. [PMID: 31188745 DOI: 10.1515/cclm-2018-0957] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 02/27/2019] [Indexed: 12/13/2022]
Abstract
Background The serum concentration of thyrotropin (TSH) represents a first-line test in diagnostic algorithms. The estimation of TSH reference intervals (RIs) is still a matter of debate due to the high prevalence of subclinical disease making difficult the definition of truly healthy subjects. The aim of this study was to estimate TSH RIs in healthy subjects and to evaluate the effect of age and gender on TSH concentration. Methods Forty-four thousand one hundred and fifty-six TSH data were collected between July 2012 and April 2018 at the Department of Laboratory Medicine, University-Hospital, Palermo. Common and sex-specific RIs were estimated by Arzideh's indirect method after exclusion of individuals younger than 15 years, subjects with repeated TSH tests and with abnormal free thyroxine (fT4), free triiodothyronine (fT3) or anti-thyroid-peroxidase antibodies. The combined effect of age and gender on TSH values was evaluated. Results RIs estimated in the selected individuals (n = 22602) were, respectively, 0.18-3.54 mIU/L (general), 0.19-3.23 mIU/L (men) and 0.18-3.94 mIU/L (women). Women showed significantly higher median TSH than men (1.46 vs. 1.39 mIU/L; p < 0.0001). Both in men and in women, median TSH decreased along with age; however, although up to 60 years in both men and women showed similar values, afterwards women showed constantly higher TSH than men. Accordingly, statistical analysis showed a significant interaction between gender and age (p = 0.001), suggesting that the effect of age on TSH is different between genders. Conclusions Our findings suggest that the indirect method, with appropriate cleaning of data, could be useful to define TSH RIs.
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Affiliation(s)
- Bruna Lo Sasso
- Institute of Clinical Biochemistry, Clinical Molecular Medicine and Laboratory Medicine, Department of Biomedicine, Neurosciences and Advanced Diagnostics, University of Palermo, Palermo, Italy
| | - Matteo Vidali
- Clinical Chemistry Unit, Maggiore della Carità Hospital, Novara, Italy
| | - Concetta Scazzone
- Institute of Clinical Biochemistry, Clinical Molecular Medicine and Laboratory Medicine, Department of Biomedicine, Neurosciences and Advanced Diagnostics, University of Palermo, Palermo, Italy
| | - Luisa Agnello
- Institute of Clinical Biochemistry, Clinical Molecular Medicine and Laboratory Medicine, Department of Biomedicine, Neurosciences and Advanced Diagnostics, University of Palermo, Palermo, Italy
| | - Marcello Ciaccio
- Institute of Clinical Biochemistry, Clinical Molecular Medicine and Laboratory Medicine, Department of Biomedicine, Neurosciences and Advanced Diagnostics, University of Palermo, Palermo, Italy.,Department of Laboratory Medicine, University Hospital, Palermo, Italy
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Mohamed Mokhtar K. Establishment of age-related prostate-specific antigen (PSA) reference limits in the Algerian population: A comparison of four indirect methods. Clin Chim Acta 2020; 507:149-155. [DOI: 10.1016/j.cca.2020.04.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/15/2020] [Accepted: 04/20/2020] [Indexed: 11/24/2022]
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Klawonn F, Hoffmann G, Orth M. Quantitative laboratory results: normal or lognormal distribution? J LAB MED 2020. [DOI: 10.1515/labmed-2020-0005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Abstract
The identification of a suitable distribution model is a prerequisite for the parametric estimation of reference intervals and other statistical laboratory tasks. Classification of normal vs. lognormal distributions from healthy populations is easy, but from mixed populations, containing unknown proportions of abnormal results, it is challenging. We demonstrate that Bowley’s skewness coefficient differentiates between normal and lognormal distributions. This classifier is robust and easy to calculate from the quartiles Q1–Q3 according to the formula (Q1 − 2 · Q2 + Q3)/(Q3 − Q1). We validate our algorithm with a more complex procedure, which optimizes the exponent λ of a power transformation. As a practical application, we show that Bowley’s skewness coefficient is suited selecting the adequate distribution model for the estimation of reference limits according to a recent International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) recommendation, especially if the data is right-skewed.
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Affiliation(s)
- Frank Klawonn
- Helmholtz Centre for Infection Research , Braunschweig , Germany
- Ostfalia University , Wolfenbüttel , Germany
| | - Georg Hoffmann
- German Heart Center , Munich , Germany
- Trillium GmbH Medizinischer Fachverlag , Grafrath , Germany
| | - Matthias Orth
- Vinzenz von Paul Kliniken gGmbH , Stuttgart , Germany
- Medizinische Fakultät Mannheim, Ruprecht Karls Universität , Mannheim , Germany
- Institut für Laboratoriumsmedizin , Adlerstr. 7 , 70199 Stuttgart , Germany
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Haeckel R, Wosniok W, Torge A, Junker R. Age- and sex-dependent reference intervals for uric acid estimated by the truncated minimum chi-square (TMC) approach, a new indirect method. J LAB MED 2020. [DOI: 10.1515/labmed-2019-0164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Background
Although the concentration of uric acid in serum or plasma is known to depend on sex and age and is subject to diurnal variation, the influence of these covariates on the reference interval (RI) is often neglected. Consequently, the values in the literature vary considerably. Therefore, we reinvestigated the reference limits and their dependence on covariates.
Methods
A new indirect approach was applied which derives a continuous function between age and RIs avoiding the usual “jumps” between various age groups.
Results
It is confirmed that the uric acid concentration in women is lower than in men. The RIs increase with age, in women more than in men. Between 80 and 90 years of age, the upper RI limit (RL) approximately reaches the same level in both sexes. Because the uric acid concentration may indicate renal insufficiency, the concentrations of creatinine and cystatin C were also measured. Both measurands showed the same behaviour as uric acid. Therefore, the age and sex dependency should be considered if the uric acid concentration is used as an indicator for hyperuricaemia (e.g. caused by gout or other metabolic diseases). Furthermore, a diurnal variation was observed.
Conclusions
Due to the variations of various covariates (age, sex, daytime, analytical systems), it is recommended that each laboratory should estimate its own RIs.
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Affiliation(s)
- Rainer Haeckel
- Institute for Laboratory Medicine , Katrepeler Landstr. 45E , 28357 Bremen , Germany , Phone: +49 412 273448
| | - Werner Wosniok
- Institut für Statistik , Universität Bremen , Bremen , Germany
| | - Antje Torge
- Institut für Klinische Chemie , Universitätsklinikum Schleswig-Holstein , Kiel , Germany
| | - Ralf Junker
- Institut für Klinische Chemie , Universitätsklinikum Schleswig-Holstein , Kiel , Germany
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Paquette P, Higgins J, Danino MA, Harris P, Lamontagne M, Gagnon DH. Effects of a preoperative neuromobilization program offered to individuals with carpal tunnel syndrome awaiting carpal tunnel decompression surgery: A pilot randomized controlled study. JOURNAL OF HAND THERAPY : OFFICIAL JOURNAL OF THE AMERICAN SOCIETY OF HAND THERAPISTS 2020. [PMID: 32151500 DOI: 10.1016/b978-0-12-815499-1.00003-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
STUDY DESIGN Pilot randomized controlled trial with parallel groups. INTRODUCTION Engaging individuals with carpal tunnel syndrome (CTS) awaiting carpal tunnel decompression surgery in a preoperative rehabilitation program may mitigate pain and sensorimotor impairments, enhance functional abilities before surgery, and improve postoperative outcomes. PURPOSE OF THE STUDY To assess the feasibility and the efficacy of a novel preoperative neuromobilization exercise program (NEP). METHODS Thirty individuals with CTS were randomly allocated into a four-week home-based neuromobilization exercise group or a standard care group while awaiting surgery. Outcome measures included feasibility (ie, recruitment, attrition, adherence, satisfaction, and safety) and efficacy metrics (ie, median nerve integrity and neurodynamics, tip pinch grip, pain, and upper limb functional abilities) collected before (ie, at the baseline and about four weeks later) and four weeks after surgery. RESULTS Thirty individuals with CTS were recruited (recruitment rate = 11.8%) and 25 completed the study (attrition rate = 16.7%). Adherence (94%) and satisfaction with the program (eg, enjoy the exercises and likeliness to repeat the NEP (≥4.2/5) were high and no serious adverse event was reported. NEP-related immediate pre- and post-surgery beneficial effects on pain interference were documented (P = .05, η2 = .10), whereas an overall increased neurodynamics (P = .04, η2 = .11) and decreased pain severity (P = .01, η2 = .21) were observed. DISCUSSION Engaging in the proposed NEP has limited beneficial effect as a stand-alone intervention on pre- and post-surgery outcomes for individuals with CTS. Expanding the program's content and attribute by adding other components including desensitization maneuvers and novel therapies promoting corticospinal plasticity is recommended. CONCLUSION A preoperative NEP completed by individuals with CTS awaiting surgery is feasible, acceptable, and safe. However, given the limited beneficial effectsof the program, revision of its content and attributes is recommended before proceeding to large-scale trials.
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Affiliation(s)
- Philippe Paquette
- Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal, Institut universitaire sur la réadaptation en déficience physique de Montréal, Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Centre-Sud-de-l'Île-de-Montréal, Montreal, Canada; School of Rehabilitation, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Johanne Higgins
- Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal, Institut universitaire sur la réadaptation en déficience physique de Montréal, Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Centre-Sud-de-l'Île-de-Montréal, Montreal, Canada; School of Rehabilitation, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Michel Alain Danino
- Department of Surgery, Centre Hospitalier de l'Université de Montréal, Montreal, Canada
| | - Patrick Harris
- Department of Surgery, Centre Hospitalier de l'Université de Montréal, Montreal, Canada
| | - Martin Lamontagne
- Department of Physical Medicine and Rehabilitation, Centre Hospitalier de l'Université de Montréal, Montreal, Canada
| | - Dany H Gagnon
- Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal, Institut universitaire sur la réadaptation en déficience physique de Montréal, Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Centre-Sud-de-l'Île-de-Montréal, Montreal, Canada; School of Rehabilitation, Faculty of Medicine, Université de Montréal, Montreal, Canada.
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Zierk J, Arzideh F, Kapsner LA, Prokosch HU, Metzler M, Rauh M. Reference Interval Estimation from Mixed Distributions using Truncation Points and the Kolmogorov-Smirnov Distance (kosmic). Sci Rep 2020; 10:1704. [PMID: 32015476 PMCID: PMC6997422 DOI: 10.1038/s41598-020-58749-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 01/21/2020] [Indexed: 11/09/2022] Open
Abstract
Appropriate reference intervals are essential when using laboratory test results to guide medical decisions. Conventional approaches for the establishment of reference intervals rely on large samples from healthy and homogenous reference populations. However, this approach is associated with substantial financial and logistic challenges, subject to ethical restrictions in children, and limited in older individuals due to the high prevalence of chronic morbidities and medication. We implemented an indirect method for reference interval estimation, which uses mixed physiological and abnormal test results from clinical information systems, to overcome these restrictions. The algorithm minimizes the difference between an estimated parametrical distribution and a truncated part of the observed distribution, specifically, the Kolmogorov-Smirnov-distance between a hypothetical Gaussian distribution and the observed distribution of test results after Box-Cox-transformation. Simulations of common laboratory tests with increasing proportions of abnormal test results show reliable reference interval estimations even in challenging simulation scenarios, when <20% test results are abnormal. Additionally, reference intervals generated using samples from a university hospital's laboratory information system, with a gradually increasing proportion of abnormal test results remained stable, even if samples from units with a substantial prevalence of pathologies were included. A high-performance open-source C++ implementation is available at https://gitlab.miracum.org/kosmic.
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Affiliation(s)
- Jakob Zierk
- Department of Pediatrics and Adolescent Medicine, University Hospital Erlangen, Erlangen, Germany. .,Center of Medical Information and Communication Technology, University Hospital Erlangen, Erlangen, Germany.
| | - Farhad Arzideh
- Institute of Clinical Chemistry, University of Cologne, Cologne, Germany
| | - Lorenz A Kapsner
- Center of Medical Information and Communication Technology, University Hospital Erlangen, Erlangen, Germany
| | - Hans-Ulrich Prokosch
- Chair of Medical Informatics, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Markus Metzler
- Department of Pediatrics and Adolescent Medicine, University Hospital Erlangen, Erlangen, Germany
| | - Manfred Rauh
- Department of Pediatrics and Adolescent Medicine, University Hospital Erlangen, Erlangen, Germany
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Neuwinger N, Meyer Zum Büschenfelde D, Tauber R, Kappert K. Underfilling of vacuum blood collection tubes leads to increased lactate dehydrogenase activity in serum and heparin plasma samples. Clin Chem Lab Med 2020; 58:213-221. [PMID: 31665108 DOI: 10.1515/cclm-2019-0616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 09/15/2019] [Indexed: 11/15/2022]
Abstract
Background Lactate dehydrogenase (LD) activity is routinely monitored for therapeutic risk stratification of malignant diseases, but is also prone to preanalytical influences. Methods We systematically analyzed the impact of defined preanalytical conditions on the hemolysis-susceptible parameters LD, potassium (K) and hemolysis index in vacuum blood collection tubes (serum [SE], heparin plasma [HP]). Blood was collected by venipuncture from healthy volunteers. Tubes were either filled or underfilled to approximately 50%, then processed directly or stored at room temperature for 4 h. Potassium (K), sodium (Na), chloride (Cl), LD, creatine kinase (CK), total cholesterol, and indices for hemolysis, icterus, and lipemia were analyzed. Filling velocity was determined in a subset of tubes. Findings in healthy volunteers were reconfirmed in an in-patient cohort (n = 74,751) that was analyzed for plasma yield and LD data distribution. Results LD activity was higher in HP compared to SE. Underfilling led to higher LD values (SE: +21.6%; HP: +28.3%), K (SE: +4.2%; HP: +5.3%), and hemolysis index (SE: +260.8%; HP: +210.0%), while other analytes remained largely unchanged. Filling velocity of tubes was approximately 3-fold higher in the first half compared to the second half in both HP and SE collection tubes. Importantly, plasma yield also inversely correlated with LD in routine patients. By calculating reference limits, the lowest plasma yield quartile of the patient cohort displayed LD values clearly exceeding current reference recommendations. Conclusions Underfilling of tubes leads to a higher proportion of blood aspirated with high velocity and relevant elevations in LD. This finding should be considered in cases of clinically implausible elevated LD activities.
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Affiliation(s)
- Nick Neuwinger
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Berlin, Germany.,Labor Berlin - Charité Vivantes GmbH, Berlin, Germany
| | - Dirk Meyer Zum Büschenfelde
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Berlin, Germany.,Labor Berlin - Charité Vivantes GmbH, Berlin, Germany
| | - Rudolf Tauber
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Berlin, Germany.,Labor Berlin - Charité Vivantes GmbH, Berlin, Germany
| | - Kai Kappert
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Berlin, Germany.,Labor Berlin - Charité Vivantes GmbH, Berlin, Germany, Phone: +49-30-450 525 308, Fax: +49-30-450 525 901
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Wosniok W, Haeckel R. A new indirect estimation of reference intervals: truncated minimum chi-square (TMC) approach. ACTA ACUST UNITED AC 2019; 57:1933-1947. [DOI: 10.1515/cclm-2018-1341] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 05/19/2019] [Indexed: 01/22/2023]
Abstract
Abstract
All known direct and indirect approaches for the estimation of reference intervals (RIs) have difficulties in processing very skewed data with a high percentage of values at or below the detection limit. A new model for the indirect estimation of RIs is proposed, which can be applied even to extremely skewed data distributions with a relatively high percentage of data at or below the detection limit. Furthermore, it fits better to some simulated data files than other indirect methods. The approach starts with a quantile-quantile plot providing preliminary estimates for the parameters (λ, μ, σ) of the assumed power normal distribution. These are iteratively refined by a truncated minimum chi-square (TMC) estimation. The finally estimated parameters are used to calculate the 95% reference interval. Confidence intervals for the interval limits are calculated by the asymptotic formula for quantiles, and tolerance limits are determined via bootstrapping. If age intervals are given, the procedure is applied per age interval and a spline function describes the age dependency of the reference limits by a continuous function. The approach can be performed in the statistical package R and on the Excel platform.
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Affiliation(s)
- Werner Wosniok
- Institut für Statistik, Universität Bremen , Bremen , Germany
| | - Rainer Haeckel
- Bremer Zentrum für Laboratoriumsmedizin, Klinikum Bremen Mitte , 28305 Bremen , Germany , Phone: +49 412 273446
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A practical guide to validation and verification of analytical methods in the clinical laboratory. Adv Clin Chem 2019; 90:215-281. [PMID: 31122610 DOI: 10.1016/bs.acc.2019.01.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Although the measures to improve quality in the clinical laboratory have been enormous in the past years, not least of all due to the introduction of the ISO standards 15189 and 17025, the handling of validation and verification of method performance often still differs widely from laboratory to laboratory. Much of what is published on the topic contains complex statistics and is difficult to implement in routine laboratories. The result is, that this point is often neglected or implemented incorrectly, which in turn can lead to false conclusions about method performances, potentially compromising patient safety or contributing to incorrect diagnoses. As it has long become a standard requirement for accredited laboratories to evaluate and document the analytical performance of all methods not only prior to their first implementation, but also during ongoing operation, there is a need for clear, standardized and practical guidelines on the subject. This review summarizes the current literature on the topic, focusing on the requirements for method validations, or as the case may be, verifications and describes when to validate, when to verify and which statistical tests are appropriate for each. Proper interpretation of statistical test results and acceptance criteria for each procedure are alluded to. Specific topics, which are addressed, are precision and bias verification of quantitative, qualitative and semi-quantitative procedures, method comparisons with Bland-Altman Plots, Passing-Bablok regression analysis, 2×2 contingency tables and bubble charts, linearity studies, analytical sensitivity and specificity, performing carry-over studies and establishing and confirming reference ranges.
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Holmes DT, Buhr KA. Widespread Incorrect Implementation of the Hoffmann Method, the Correct Approach, and Modern Alternatives. Am J Clin Pathol 2019; 151:328-336. [PMID: 30475946 DOI: 10.1093/ajcp/aqy149] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Objectives The Hoffmann method is a procedure for reference interval estimation using routine clinical results. Many authors incorrectly prepare Hoffmann plots on a linear rather than normal probability scale. We explore the consequences. Methods This was investigated algebraically, by random number simulations (45 simulations, n = 100,000 each) and using clinical data sets. Strategies compared were: Hoffmann's method as originally and incorrectly implemented, Bhattacharya's method, and maximum likelihood (ML). All R source code and data sets are provided. Results As the proportion of healthy individuals approaches 1, the incorrect approach generates reference interval estimates of approximately μH ± 1.19 σH delineating the central 77% of the healthy subpopulation, not the central 95%. Inappropriately narrow reference interval estimates were seen on random simulations and clinical data sets. ML methods performed best. Conclusions The erroneous variant Hoffmann method should not be used. ML methods outperform others and are not restricted by Gaussian assumptions.
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Affiliation(s)
- Daniel T Holmes
- Department of Pathology and Laboratory Medicine, St Paul’s Hospital, Vancouver, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada
| | - Kevin A Buhr
- Biostatistics and Medical Informatics, University of Wisconsin, Madison
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Abstract
Reference intervals are relied upon by clinicians when interpreting their patients' test results. Therefore, laboratorians directly contribute to patient care when they report accurate reference intervals. The traditional approach to establishing reference intervals is to perform a study on healthy volunteers. However, the practical aspects of the staff time and cost required to perform these studies make this approach difficult for clinical laboratories to routinely use. Indirect methods for deriving reference intervals, which utilise patient results stored in the laboratory's database, provide an alternative approach that is quick and inexpensive to perform. Additionally, because large amounts of patient data can be used, the approach can provide more detailed reference interval information when multiple partitions are required, such as with different age-groups. However, if the indirect approach is to be used to derive accurate reference intervals, several considerations need to be addressed. The laboratorian must assess whether the assay and patient population were stable over the study period, whether data 'clean-up' steps should be used prior to data analysis and, often, how the distribution of values from healthy individuals should be modelled. The assumptions and potential pitfalls of the particular indirect technique chosen for data analysis also need to be considered. A comprehensive understanding of all aspects of the indirect approach to establishing reference intervals allows the laboratorian to harness the power of the data stored in their laboratory database and ensure the reference intervals they report are accurate.
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Jones GRD, Haeckel R, Loh TP, Sikaris K, Streichert T, Katayev A, Barth JH, Ozarda Y. Indirect methods for reference interval determination - review and recommendations. Clin Chem Lab Med 2018; 57:20-29. [PMID: 29672266 DOI: 10.1515/cclm-2018-0073] [Citation(s) in RCA: 158] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 03/15/2018] [Indexed: 01/29/2023]
Abstract
Reference intervals are a vital part of the information supplied by clinical laboratories to support interpretation of numerical pathology results such as are produced in clinical chemistry and hematology laboratories. The traditional method for establishing reference intervals, known as the direct approach, is based on collecting samples from members of a preselected reference population, making the measurements and then determining the intervals. An alternative approach is to perform analysis of results generated as part of routine pathology testing and using appropriate statistical techniques to determine reference intervals. This is known as the indirect approach. This paper from a working group of the International Federation of Clinical Chemistry (IFCC) Committee on Reference Intervals and Decision Limits (C-RIDL) aims to summarize current thinking on indirect approaches to reference intervals. The indirect approach has some major potential advantages compared with direct methods. The processes are faster, cheaper and do not involve patient inconvenience, discomfort or the risks associated with generating new patient health information. Indirect methods also use the same preanalytical and analytical techniques used for patient management and can provide very large numbers for assessment. Limitations to the indirect methods include possible effects of diseased subpopulations on the derived interval. The IFCC C-RIDL aims to encourage the use of indirect methods to establish and verify reference intervals, to promote publication of such intervals with clear explanation of the process used and also to support the development of improved statistical techniques for these studies.
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Affiliation(s)
- Graham R D Jones
- Department of Chemical Pathology, SydPath, St Vincent's Hospital, Sydney, NSW, Australia
- University of NSW, Sydney, NSW, Australia
| | - Rainer Haeckel
- Institute for Laboratory Medicine, Klinikum Bremen-Mitte, Bremen, Germany
| | - Tze Ping Loh
- Department of Laboratory Medicine, National University Hospital, Singapore, Singapore
| | - Ken Sikaris
- Department of Pathology, Melbourne University, Parkville, Melbourne, Australia
- Sonic Healthcare, Sydney, NSW, Australia
| | | | - Alex Katayev
- Department of Science and Technology, Laboratory Corporation of America Holdings, Elon, NC, USA
| | | | - Yesim Ozarda
- Department of Medical Biochemistry, Uludag University School of Medicine, Bursa, Turkey
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Özçürümez MK, Haeckel R. Biological variables influencing the estimation of reference limits. Scandinavian Journal of Clinical and Laboratory Investigation 2018; 78:337-345. [PMID: 29764232 DOI: 10.1080/00365513.2018.1471617] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Reference limits (RLs) are required to evaluate laboratory results for medical decisions. The establishment of RL depends on the pre-analytical and the analytical conditions. Furthermore, biological characteristics of the sub-population chosen to provide the reference samples may influence the RL. The most important biological preconditions are gender, age, chronobiological influences, posture, regional and ethnic effects. The influence of these components varies and is often neglected. Therefore, a list of biological variables is collected from the literature and their influence on the estimation of RL is discussed. Biological preconditions must be specified if RL are reported as well for directly as for indirectly estimated RL. The influence of biological variables is especially important if RL established by direct methods are compared with those derived from indirect techniques. Even if these factors are not incorporated into the estimation of RL, their understanding can assist the interpretation of laboratory results of an individual.
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Affiliation(s)
- Mustafa K Özçürümez
- a IMD-Oderland GmbH , Frankfurt (Oder) , Germany.,b Institut für Klinische Chemie Medizinische Fakultät Mannheim der Universität Heidelberg , Mannheim , Germany
| | - Rainer Haeckel
- c Bremer Zentrum für Laboratoriumsmedizin Klinikum Bremen Mitte , Bremen , Germany
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Dynamic reference intervals for coagulation parameters from infancy to adolescence. Clin Chim Acta 2018; 482:124-135. [PMID: 29626437 DOI: 10.1016/j.cca.2018.04.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 04/03/2018] [Indexed: 11/23/2022]
Abstract
INTRODUCTION Practical and ethical challenges as well as time and costs have restricted the generation of pediatric reference intervals. Therefore, pediatric reference intervals on coagulation parameters based on solid evidence are still scarce. Furthermore, reference intervals by age-group cannot reflect the dynamics of age and sex specific coagulation values during childhood. This study is the first to close this gap and provide continuous age and sex dependent reference intervals during childhood in hemostasis. METHODS We used an innovative indirect method for providing continuous reference intervals for five common coagulation parameters: Activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin clotting time (TT), fibrinogen (FIB) and antithrombin (AT). Calculations were performed using retrospective laboratory data from pediatric patients between 2005 and 2015 of two major Austrian hospitals, resulting in a total of 195.360 measurements (aPTT: 55,100; PT: 35,492; TT: 35,295; FIB: 49,789; AT: 19,684). RESULTS This multicenter study provides calculations of continuous reference intervals for five common coagulation parameters in a large pediatric cohort, accounting for age and gender. CONCLUSION To the best of our knowledge, this is the first multicenter study, determining continuous pediatric coagulation reference intervals based on a large retrospective dataset.
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Haeckel R. The influence of age and other biological variables on the estimation of reference limits of cardiac troponin T. ACTA ACUST UNITED AC 2017; 56:685-687. [DOI: 10.1515/cclm-2017-1082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Rainer Haeckel
- Institute for Laboratory Medicine , Katrepeler Landstr. 45 E , Bremen, 28357 , Germany
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Haeckel R, Wosniok W, Gurr E, Peil B. Permissible limits for uncertainty of measurement in laboratory medicine. Clin Chem Lab Med 2016; 53:1161-71. [PMID: 25720082 DOI: 10.1515/cclm-2014-0874] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 11/13/2014] [Indexed: 11/15/2022]
Abstract
The international standard ISO 15189 requires that medical laboratories estimate the uncertainty of their quantitative test results obtained from patients' specimens. The standard does not provide details how and within which limits the measurement uncertainty should be determined. The most common concept for establishing permissible uncertainty limits is to relate them on biological variation defining the rate of false positive results or to base the limits on the state-of-the-art. The state-of-the-art is usually derived from data provided by a group of selected medical laboratories. The approach on biological variation should be preferred because of its transparency and scientific base. Hitherto, all recommendations were based on a linear relationship between biological and analytical variation leading to limits which are sometimes too stringent or too permissive for routine testing in laboratory medicine. In contrast, the present proposal is based on a non-linear relationship between biological and analytical variation leading to more realistic limits. The proposed algorithms can be applied to all measurands and consider any quantity to be assured. The suggested approach tries to provide the above mentioned details and is a compromise between the biological variation concept, the GUM uncertainty model and the technical state-of-the-art.
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