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Long B, Long DA, Koyfman A. Emergency medicine misconceptions: Utility of routine coagulation panels in the emergency department setting. Am J Emerg Med 2020; 38:1226-1232. [PMID: 32029342 DOI: 10.1016/j.ajem.2020.01.057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 12/17/2019] [Accepted: 01/28/2020] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Coagulation panels are ordered for a variety of conditions in the emergency department (ED). OBJECTIVE This narrative review evaluates specific conditions for which a coagulation panel is commonly ordered but has limited utility in medical decision-making. DISCUSSION Coagulation panels consist of partial thromboplastin time (PTT) or activated partial thromboplastin time (aPTT), prothrombin time (PT), and international normalized ratio (INR). These tests evaluate the coagulation pathway which leads to formation of a fibrin clot. The coagulation panel can monitor warfarin and heparin therapy, evaluate for vitamin K deficiency, evaluate for malnutrition or severe systemic disease, and assess hemostatic function in the setting of bleeding. The utility of coagulation testing in chest pain evaluation, routine perioperative assessment, prior to initiation of anticoagulation, and as screening for admitted patients is low, with little to no change in patient management based on results of these panels. Coagulation testing should be considered in systemically ill patients, those with a prior history of bleeding or family history of bleeding, patients on anticoagulation, or patients with active hemorrhage and signs of bleeding. Thromboelastography and rotational thromboelastometry offer more reliable measures of coagulation function. CONCLUSIONS Little utility for coagulation assessment is present for the evaluation of chest pain, routine perioperative assessment, initiation of anticoagulation, and screening for admitted patients. However, coagulation panel assessment should be considered in patients with hemorrhage, patients on anticoagulation, and personal history or family history of bleeding.
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Affiliation(s)
- Brit Long
- Brooke Army Military Medical Center, Department of Emergency Medicine, 3841 Roger Brooke Dr, Fort Sam Houston, TX 78234, United States.
| | - Drew A Long
- Brooke Army Military Medical Center, Department of Emergency Medicine, 3841 Roger Brooke Dr, Fort Sam Houston, TX 78234, United States
| | - Alex Koyfman
- The University of Texas Southwestern Medical Center, Department of Emergency Medicine, 5323 Harry Hines Boulevard, Dallas, TX 75390, United States
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Efthymiou M, Mackie IJ, Lane PJ, Andrade D, Willis R, Erkan D, Sciascia S, Krillis S, Bison E, Borges Galhardo Vendramini M, Romay-Penabad Z, Qi M, Tektonidou M, Ugarte A, Chighizola C, Belmont HM, Aguirre MA, Ji L, Branch DW, de Jesus G, Fortin PR, Andreoli L, Petri M, Cervera R, Rodriguez E, Knight JS, Atsumi T, Vega J, Sevim E, Bertolaccini ML, Pengo V, Cohen H. Comparison of real world and core laboratory lupus anticoagulant results from the Antiphospholipid Syndrome Alliance for Clinical Trials and International Networking (APS ACTION) clinical database and repository. J Thromb Haemost 2019; 17:2069-2080. [PMID: 31364274 DOI: 10.1111/jth.14596] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 07/25/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND Variability remains a challenge in lupus anticoagulant (LA) testing. OBJECTIVE To validate LA test performance between Antiphospholipid Syndrome Alliance for Clinical Trials and International Networking (APS ACTION) Core laboratories and examine agreement in LA status between Core and local/hospital laboratories contributing patients to this prospective registry. METHODS Five Core laboratories used the same reagents, analyzer type, protocols, and characterized samples for LA validation. Non-anticoagulated registry samples were retested at the corresponding regional Core laboratories and anticoagulated samples at a single Core laboratory. Categorical agreement and discrepancies in LA status between Core and local/hospital laboratories were analyzed. RESULTS Clotting times for the reference/characterized plasmas used for normalized ratios were similar between Core laboratories (CV <4%); precision and agreement for LA positive/negative plasma were similar (all CV ≤5%) in the four laboratories that completed both parts of the validation exercise; 418 registry samples underwent LA testing. Agreement for LA positive/negative status between Core and local/hospital laboratories was observed in 87% (115/132) non-anticoagulated and 77% (183/237) anticoagulated samples. However, 28.7% (120/418) of samples showed discordance between the Core and local/hospital laboratories or equivocal LA results. Some of the results of the local/hospital laboratories might have been unreliable in 24.7% (41/166) and 23% (58/252) of the total non-anticoagulated and anticoagulated samples, respectively. Equivocal results by the Core laboratory might have also contributed to discordance. CONCLUSIONS Laboratories can achieve good agreement in LA performance by use of the same reagents, analyzer type, and protocols. The standardized Core laboratory results underpin accurate interpretation of APS ACTION clinical data.
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Affiliation(s)
- Maria Efthymiou
- Haemostasis Research Unit, Department of Haematology, University College London, London, UK
| | - Ian J Mackie
- Haemostasis Research Unit, Department of Haematology, University College London, London, UK
| | - Philip J Lane
- Haemostasis Research Unit, Department of Haematology, University College London, London, UK
| | | | - Rohan Willis
- Antiphospholipid Standardization Laboratory, University of Texas Medical Branch, Galveston, TX, USA
| | - Doruk Erkan
- Barbara Volcker Center for Women and Rheumatic Diseases, Hospital for Special Surgery, Weill Cornell Medicine, New York, NY, USA
| | - Savino Sciascia
- Center of Research of Immunopathology and Rare Diseases, University of Turin, Turin, Italy
| | - Steven Krillis
- Department of Infectious Diseases, Immunology and Sexual Health, St George Hospital, Sydney, NSW, Australia
| | | | | | - Zurina Romay-Penabad
- Antiphospholipid Standardization Laboratory, University of Texas Medical Branch, Galveston, TX, USA
| | - Miao Qi
- Department of Infectious Diseases, Immunology and Sexual Health, St George Hospital, Sydney, NSW, Australia
| | | | - Amaia Ugarte
- Internal Medicine, Hospital Universitario Cruces, Barakaldo, País Vasco, Spain
| | | | | | | | - Lanlan Ji
- Rheumatology and Immunology Department, Peking University First Hospital, Beijing, China
| | - D Ware Branch
- University of Utah and Intermountain Healthcare, Salt Lake City, UT, USA
| | | | - Paul R Fortin
- CHU de Quebec - Université Laval, Quebec, QC, Canada
| | - Laura Andreoli
- Rheumatology and Clinical Immunology, Spedali Civili, Brescia, Italy
- Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
| | - Michelle Petri
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ricard Cervera
- Department of Autoimmune Diseases, Hospital Clínic Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain
| | | | - Jason S Knight
- Division of Rheumatology, University of Michigan, Ann Arbor, MI, USA
| | | | - Joann Vega
- University Hospital Padova, Padova, Italy
| | - Ecem Sevim
- University Hospital Padova, Padova, Italy
| | - Maria Laura Bertolaccini
- Academic Department of Vascular Surgery, School of Cardiovascular Medicine & Sciences, King's College London, London, UK
| | - Vittorio Pengo
- Department of Infectious Diseases, Immunology and Sexual Health, St George Hospital, Sydney, NSW, Australia
| | - Hannah Cohen
- Haemostasis Research Unit, Department of Haematology, University College London, London, UK
- Department of Haematology, University College London Hospitals NHS Foundation Trust, London, UK
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Moore GW, Van Cott EM, Cutler JA, Mitchell MJ, Adcock DM. Recommendations for clinical laboratory testing of activated protein C resistance; communication from the SSC of the ISTH. J Thromb Haemost 2019; 17:1555-1561. [PMID: 31317658 DOI: 10.1111/jth.14532] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 06/04/2019] [Accepted: 06/05/2019] [Indexed: 12/29/2022]
Affiliation(s)
- Gary W Moore
- Diagnostic Haemostasis and Thrombosis, Viapath Analytics, Guy's & St Thomas' Hospitals, London, UK
| | | | - Jacqueline A Cutler
- Molecular Haemostasis and Thrombosis, Viapath Analytics, Guy's & St Thomas' Hospitals, London, UK
| | - Michael J Mitchell
- Molecular Haemostasis and Thrombosis, Viapath Analytics, Guy's & St Thomas' Hospitals, London, UK
| | - Dorothy M Adcock
- Colorado Coagulation, Laboratory Corporation of America Holdings, Englewood, Colorado
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van den Besselaar AMHP, Chantarangkul V, Angeloni F, Binder NB, Byrne M, Dauer R, Gudmundsdottir BR, Jespersen J, Kitchen S, Legnani C, Lindahl TL, Manning RA, Martinuzzo M, Panes O, Pengo V, Riddell A, Subramanian S, Szederjesi A, Tantanate C, Herbel P, Tripodi A. International collaborative study for the calibration of proposed International Standards for thromboplastin, rabbit, plain, and for thromboplastin, recombinant, human, plain. J Thromb Haemost 2018; 16:142-149. [PMID: 29065247 DOI: 10.1111/jth.13879] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Indexed: 11/28/2022]
Abstract
Essentials Two candidate International Standards for thromboplastin (coded RBT/16 and rTF/16) are proposed. International Sensitivity Index (ISI) of proposed standards was assessed in a 20-centre study. The mean ISI for RBT/16 was 1.21 with a between-centre coefficient of variation of 4.6%. The mean ISI for rTF/16 was 1.11 with a between-centre coefficient of variation of 5.7%. SUMMARY Background The availability of International Standards for thromboplastin is essential for the calibration of routine reagents and hence the calculation of the International Normalized Ratio (INR). Stocks of the current Fourth International Standards are running low. Candidate replacement materials have been prepared. This article describes the calibration of the proposed Fifth International Standards for thromboplastin, rabbit, plain (coded RBT/16) and for thromboplastin, recombinant, human, plain (coded rTF/16). Methods An international collaborative study was carried out for the assignment of International Sensitivity Indexes (ISIs) to the candidate materials, according to the World Health Organization (WHO) guidelines for thromboplastins and plasma used to control oral anticoagulant therapy with vitamin K antagonists. Results Results were obtained from 20 laboratories. In several cases, deviations from the ISI calibration model were observed, but the average INR deviation attributabled to the model was not greater than 10%. Only valid ISI assessments were used to calculate the mean ISI for each candidate. The mean ISI for RBT/16 was 1.21 (between-laboratory coefficient of variation [CV]: 4.6%), and the mean ISI for rTF/16 was 1.11 (between-laboratory CV: 5.7%). Conclusions The between-laboratory variation of the ISI for candidate material RBT/16 was similar to that of the Fourth International Standard (RBT/05), and the between-laboratory variation of the ISI for candidate material rTF/16 was slightly higher than that of the Fourth International Standard (rTF/09). The candidate materials have been accepted by WHO as the Fifth International Standards for thromboplastin, rabbit plain, and thromboplastin, recombinant, human, plain.
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Affiliation(s)
- A M H P van den Besselaar
- Department of Thrombosis and Hemostasis, and Coagulation Reference Laboratory, Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | | | - F Angeloni
- Hemostasis Reference Laboratory, Hamilton, Canada
| | | | - M Byrne
- National Coagulation Laboratory, St James's Hospital, Dublin, Ireland
| | - R Dauer
- Haematology Laboratory, Pathology Department, Alfred Health, Melbourne, Australia
| | - B R Gudmundsdottir
- Department of Laboratory Hematology and Hemostasis Center, Landspitali University Hospital and University of Iceland School of Medicine, Reykjavik, Iceland
| | - J Jespersen
- Department of Clinical Biochemistry, Hospital of South West Jutland and Unit for Health Promotion Research, Institute of Public Health, University of Southern Denmark, Esbjerg, Denmark
| | - S Kitchen
- Sheffield Haemophilia and Thrombosis Centre, Royal Hallamshire Hospital, Sheffield, UK
| | - C Legnani
- Department of Angiology and Blood Coagulation, University Hospital S. Orsola-Malpighi, Bologna, Italy
| | - T L Lindahl
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - R A Manning
- Department of Coagulation, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK
| | - M Martinuzzo
- Grupo Bioquímico, Laboratorio Central del Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - O Panes
- Department of Hematology-Oncology, School of Medicine, Pontifical Catholic University of Chile, Santiago, Chile
| | - V Pengo
- Clinical Cardiology, Department of Cardiac, Thoracic, and Vascular Sciences, University of Padova, Padova, Italy
| | - A Riddell
- Haemophilia Laboratory (HSL), Katharine Dormandy Haemophilia and Thrombosis Centre, Royal Free Hospital, London, UK
| | - S Subramanian
- Department of Transfusion Medicine and Immunohaematology, St John's Medical College Hospital, Bangalore, India
| | - A Szederjesi
- Hemostasis Laboratory, St István and St László Hospital, Budapest, Hungary
| | - C Tantanate
- Department of Clinical Pathology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - P Herbel
- Roche Diagnostics GmbH Mannheim, Mannheim, Germany
| | - A Tripodi
- Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Department of Clinical Sciences and Community Health, Università degli Studi di Milano and IRCCS Cà Granda Maggiore Hospital Foundation, Milano, Italy
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Lindahl TL, Egberg N, Hillarp A, Ødegaard OR, Edlund B, Svensson J, Sandset PM, Rånby M. INR calibration of Owren-type prothrombin time based on the relationship between PT% and INR utilizing normal plasma samples. Thromb Haemost 2017; 91:1223-31. [PMID: 15175811 DOI: 10.1160/th03-07-0456] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
SummaryProthrombin time (PT) is clinically important and is used to monitor oral anticoagulant therapy. To obtain PT results in international normalized ratio (INR), the current standardization procedure is complex and involves reference reagents.The PT of diluted plasma samples can be determined with a combined thromboplastin (the Owren-type procedure), but not necessarily with a plain thromboplastin (the Quick-type procedure). Owren-type PT procedures can therefore, as an alternative to the INR calibration, be calibrated with diluted normal plasma to give PT results in percent of normal PT activity (PT%).The present study explored if a plasma-based calibration of an Owren-type PT procedure can be used to obtain results in INR. The approach was to establish a relationship between PT% and INR by multi-center analysis of 365 samples from healthy individuals and patients on warfarin treatment. INR values were obtained by manual Quick-type reference procedure and PT% values by various automated Owren-type procedures. A relationship INR = (1/PT% + 0.018)/0.028 was found. A calibration procedure, based on the relationship, was investigated. Calibrators were the median PT of 21 normal plasma at dilutions representing 100%, 50%, 25%, 12.5% and 6.25% of normal PT activity. These were assigned INR values of 1.00, 1.36, 2.07, 3.05 and 6.36. Calibration of various Owren-type assays was repeatedly performed by 5 expert laboratories during 3 consecutive years. The INR values of certain lyophilised or frozen control plasmas were determined. The frozen control plasmas had externally assigned INR values according to WHO guidelines. Within the laboratory, CV was typically below 3%. No appreciable difference among the results of the different laboratories or the three assay occasions was found. Externally assigned and INR values were essentially identical to those found. These and other results indicated that the calibration procedure was reproducible, precise and accurate. Thus, an Owren-type PT assay can be calibrated with normal plasma samples to give results in INR and the investigated calibration procedure can be proposed for this purpose.
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Affiliation(s)
- Tomas L Lindahl
- Department of Clinical Chemistry, University Hospital of Linköping, Sweden.
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6
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Hillarp A, Egberg N, Nordin G, Stigendal L, Fagerberg I, Lindahl TL. Local INR calibration of the Owren type prothrombin assay greatly improves the intra- and interlaboratory variation. Thromb Haemost 2017; 91:300-7. [PMID: 14961158 DOI: 10.1160/th03-07-0419] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
SummaryIn 1999, a simplified procedure for calibration of the Owren prothrombin time (Owren PT) assay was introduced by a working group of the organisation for national quality assurance in laboratory medicine in Sweden. The new protocol allowed local calibration by means of only two lyophilised national plasma calibrators and expression of results as an international normalized ratio (INR). This is our report of a three-year follow-up involving the analysis of data from all laboratories, in hospitals (n=88 in 2002) and primary health care units (n=246 in 2002) that perform the Owren PT assay in Sweden. The interlaboratory variation was significantly improved after the introduction of the new calibration procedure. For the larger hospital-based laboratories, the mean coefficient of variation (CV) was reduced from 7.9% to 5.2% (p<0.0001) when analysing test materials with INR range 2-4. In the higher INR range (>4), the CV was reduced even further, from 10.4% to 6.8% (p<0.0001). The corresponding results from smaller laboratories in the primary health care units showed a similar decrease in CV from 8.2% to 5.7% in the INR range 2-4 (p<0.0001). At the INR range >4, the CV was reduced from 9.5% to 7.8%. The intralaboratory variation was also improved for both types of laboratory categories. This study shows an improved precision, with CV less than 6% at the therapeutic INR range, for both hospital-based laboratories and smaller laboratories in the primary health care system. The results indicate that the Owren PT assay is well suited for local INR calibration employing only two calibrant plasmas in a simplified procedure.
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Affiliation(s)
- Andreas Hillarp
- Department of Clinical Chemistry, Malmö University Hospital, Malmö, Sweden.
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7
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Abstract
Hemolysis is the most common reason why coagulation test samples are rejected. However, the effects of hemolysis on plasma prothrombin time (PPT) and activated partial thromboplastin time (APTT) are rarely investigated and the results are controversial. This research aims to analyze the effects of hemolysis on PPT and APPT using the photo-optical method.Nonhemolyzed citrate blood samples (n = 30) with normal PPT and APTT underwent 2-step mechanical lysis and then hemoglobin level measurement was carried out at each step. The first lysis was mild to moderate resulting in a hemoglobin level of <0.8 g/dL. These samples were labeled as group 1. The second step showed more severe lysis, which resulted in a plasma hemoglobin level of ≥0.8 g/dL. These samples were labeled as group 2. Analysis was carried out on the PPT and APTT differences between the 2 groups and baseline, as well as between group 1 and group 2 using repeated-measures analysis of variance (ANOVA). The effects of hemolysis were analyzed using linear regression. Receiver operating characteristic (ROC) curve analysis was performed to determine the cut-off value in PPT and APTT.Significantly shorter APTT was measured for group 1 than baseline, (P = .000), group 2 than baseline (P = .000), and group 2 than group 1 (P = .003). With regard to PPT results, those for group 1 were significant shorter than baseline (P = .002), while those for group 2 were significantly longer than group 1 (P = .000). In the correlation assay, the level of hemolysis revealed a mildly significant correlation to APTT (R = 0.245; P = .02). Cut-off value for PPT was 1.55 g/dL (100% sensitivity and 87.9% specificity), while the value for APTT was 0.95 g/dL (75% sensitivity and 62.5% specificity).Not all hemolyzed samples should be rejected for PPT and APTT tests using photo-optical methods.
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Affiliation(s)
- Yetti Hernaningsih
- Department of Clinical Pathology, Faculty of Medicine Universitas Airlangga, Dr. Soetomo General Hospital, Surabaya, Jawa Timur
| | - Jeine Stela Akualing
- Clinical Pathology Laboratory, Tobelo General Hospital, North Halmahera, Indonesia
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Favaloro EJ. Optimizing the Verification of Mean Normal Prothrombin Time (MNPT) and International Sensitivity Index (ISI) for Accurate Conversion of Prothrombin Time (PT) to International Normalized Ratio (INR). Methods Mol Biol 2017; 1646:59-74. [PMID: 28804818 DOI: 10.1007/978-1-4939-7196-1_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The Prothrombin Time (PT) assay is the most common test performed in hemostasis laboratories, most commonly as converted to an international normalized ratio (INR) to monitor anticoagulant therapy using vitamin K antagonists (VKAs) such as warfarin. Although the INR is meant to standardize PT values by taking into consideration reagent and instrument variability, substantial inter-laboratory variation in INRs still exists and suggests that this can be further improved. This paper describes the PT test, its conversion to an INR value, and methods to improve the accuracy of INRs by improving the determination of critical components to the INR, namely the mean normal prothrombin time (MNPT) and the international sensitive index (ISI).
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Affiliation(s)
- Emmanuel J Favaloro
- Haematology Department, Sydney Centres for Thrombosis and Haemostasis, Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, NSW Health Pathology, Westmead, NSW, 2145, Australia.
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9
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Tripodi A, de Laat B, Wahl D, Ageno W, Cosmi B, Crowther M. Monitoring patients with the lupus anticoagulant while treated with vitamin K antagonists: communication from the SSC of the ISTH. J Thromb Haemost 2016; 14:2304-2307. [PMID: 27860336 DOI: 10.1111/jth.13481] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 08/19/2016] [Indexed: 08/31/2023]
Affiliation(s)
- A Tripodi
- Department of Clinical Sciences and Community Health, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Università degli Studi di Milano, Milan, Italy
- IRCCS Cà Granda Maggiore Hospital Foundation, Milan, Italy
| | - B de Laat
- Department of Biochemistry, Maastricht University, Maastricht, the Netherlands
| | - D Wahl
- Lorraine University, Nancy, France
| | - W Ageno
- Division of Internal Medicine, University of Insubria, Varese, Italy
| | - B Cosmi
- Department of Angiology and Blood Coagulation, S. Orsola-Malpighi University Hospital, Bologna, Italy
| | - M Crowther
- Department of Medicine, McMaster University, Hamilton, Canada
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Favaloro EJ, McVicker W, Lay M, Ahuja M, Zhang Y, Hamdam S, Hocker N. Harmonizing the International Normalized Ratio (INR) : Standardization of Methods and Use of Novel Strategies to Reduce Interlaboratory Variation and Bias. Am J Clin Pathol 2016; 145:191-202. [PMID: 26800763 DOI: 10.1093/ajcp/aqv022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
OBJECTIVES To reduce interlaboratory variation and bias in international normalized ratio (INR) results, as used to monitor patients receiving vitamin K antagonist therapy, including warfarin, in a large pathology network (n = 27 laboratories) by procedural standardization and harmonization. METHODS Network consensus to standardize to common instrument and reagent platforms was established, following development of hemostasis test specifications. Subsequent installations and implementation occurred after conclusion of a government tender process. Network-wide application of simple novel process of verification harmonization of local international sensitive index and mean normal prothrombin time initiated for each new lot of INR reagent that does not require ongoing use of reference thromboplastin or calibration/certified plasma sets. RESULTS We achieved reduction of different instrument manufacturers (from four to one), instrument types (10 to three), reagent types (four to one), and instrument/reagent combinations (12 to three), plus substantial reduction in INR variability and bias. CONCLUSIONS Results infer significant improvement in local patient management, with positive implications for other laboratories. For the United States in particular, lack of US Food and Drug Administration-cleared certified plasmas may compromise INR accuracy, and our novel approach may provide a workable alternative for laboratories and networks.
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Affiliation(s)
- Emmanuel J Favaloro
- From the Haematology Department, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology West, NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia
| | - Wendy McVicker
- From the Haematology Department, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology West, NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia
| | - Michelle Lay
- From the Haematology Department, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology West, NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia
| | - Monica Ahuja
- From the Haematology Department, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology West, NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia
| | - Yifang Zhang
- From the Haematology Department, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology West, NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia
| | - Sayed Hamdam
- Pathology Department, Pathology West, NSW Health Pathology, Blacktown Hospital, Blacktown, NSW, Australia
| | - Naomi Hocker
- Haematology Department, Pathology West, NSW Health Pathology, Wagga Wagga, NSW, Australia
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11
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Shurlock B. The Quick Test: 80 years on. Eur Heart J 2014; 35:1827-1828. [PMID: 25184176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/03/2023] Open
Abstract
Few procedures have lasted as long as the Quick Test and its later variants, but cardiologists should not accept anticoagulation data without first checking that reliable methods are being used, according to haematologist Prof. Leon Poller MD, Faculty of Life Sciences, Manchester, UK.
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12
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Austin M, Ferrell C, Reyes M. Do elevated hematocrits prolong the PT/aPTT? Clin Lab Sci 2013; 26:89-94. [PMID: 23772474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The Clinical and Laboratory Standards Institute guidelines require special processing of whole blood specimens with hematocrits greater than 55% due to the possibility of spurious prolongation of routine coagulation studies (PT, aPTT). As samples with hematocrits above 60% are rare at our institution, our study seeks to determine the effect of relative citrate excess on routine coagulation studies in samples with hematocrits of 60% to determine whether special processing is necessary. A calculated volume of 3.2% citrate was added to 1 mL aliquots of 40 whole blood samples in citrated tubes from adult patients to simulate a hematocrit of 60%. A dilutional control was created by adding an equivalent volume of saline to a separate 1 mL aliquot. Routine coagulation studies (PT, aPTT) were run on both samples on the STA Compact Analyzer in accordance with manufacturer instructions. While a paired Student's t-test demonstrated a clinically significant change in both PT and aPTT with the addition of citrate (p = 0.0002 for PT and p = 0.0234 for aPTT), clinical management would not have been altered by any observed change. More interestingly, we observed a shortening of 27/40 PTs and 23/40 aPTTs rather than the expected prolongation. Based on our data, no adjustment of citrate volume appears to be necessary in samples with hematocrits less than or equal to 60%.
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Affiliation(s)
- Melissa Austin
- Department of Pathology, University of Washington Medical Center, Seattle, WA, USA.
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Fattorini A, Crippa L, D'Angelo A. Artificially depleted plasmas are not necessarily commutable with native patient plasmas for International Sensitivity Index calibration and International Normalized Ratio derivation: a rebuttal. J Thromb Haemost 2012; 10:1715-6. [PMID: 22642315 DOI: 10.1111/j.1538-7836.2012.04795.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Harenberg J, Marx S, Weiss C, Krämer R, Samama M, Schulman S. Report of the Subcommittee of Control of Anticoagulation on the determination of the anticoagulant effects of rivaroxaban. J Thromb Haemost 2012; 10:1433-6. [PMID: 22947062 DOI: 10.1111/j.1538-7836.2012.04784.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- J Harenberg
- Department of Clinical Pharmacology, Mannheim, Germany.
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Poller L, Jespersen J, Ibrahim S. Artificially depleted plasmas are not necessarily commutable with native patient plasmas for International Sensitivity Index calibration and International Normalized Ratio derivation: a rebuttal. J Thromb Haemost 2012; 10:1197-8; author reply 1198-200. [PMID: 22487169 DOI: 10.1111/j.1538-7836.2012.04731.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
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Hayward CPM, Moffat KA, Plumhoff E, Van Cott EM. Approaches to investigating common bleeding disorders: an evaluation of North American coagulation laboratory practices. Am J Hematol 2012; 87 Suppl 1:S45-50. [PMID: 22367923 DOI: 10.1002/ajh.23124] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 01/11/2012] [Accepted: 01/12/2012] [Indexed: 11/07/2022]
Abstract
Bleeding disorders commonly result from deficiencies or defects in von Willebrand factor (VWF), platelets, coagulation factors, or fibrinolytic proteins. The primary goal of our study was to assess current North American coagulation laboratory practices for diagnosing bleeding disorders, using an on-line patterns-of-practice survey of diagnostic laboratory members of the North American Specialized Coagulation Laboratory Association. The survey examined laboratory approaches to evaluating bleeding disorders, with specific questions about the tests and test panels offered and compliance to recent guideline recommendations on diagnosing von Willebrand disease (VWD) and platelet function disorders. All laboratories responding to the survey performed a prothrombin time/international normalized ratio, an activated partial thromboplastin time, and coagulation factor assays, and many tested for VWD and platelet disorders. However, few laboratories had test panels that evaluated the more common bleeding disorders and few performed some assays, including VWF multimer assessments and assays for fibrinolytic disorders. Additionally, the cutoffs used by laboratories to diagnose type 1 VWD varied considerably, with only a minority following the National Heart Lung Blood Institute recommendations. In contrast, laboratories that tested for platelet function disorders mostly complied with aggregation testing recommendations, as published in the recent North American guidelines. Our results indicate that there are some gaps in the strategies used by laboratories to diagnose bleeding disorders that might be addressed by development of further guidelines and test algorithms that emphasize evaluations for common bleeding disorders. Laboratories may also benefit from guidelines on test interpretation, and external evaluation of their bleeding disorder testing strategies.
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Affiliation(s)
- Catherine P M Hayward
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada.
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van den Besselaar AMHP. Artificially depleted plasmas are not necessarily commutable with native patient plasmas for International Sensitivity Index calibration and International Normalized Ratio derivation. J Thromb Haemost 2012; 10:303-5. [PMID: 22136646 DOI: 10.1111/j.1538-7836.2011.04582.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Favaloro EJ, McVicker W, Zhang Y, Hamdam S, Huynh M, Peris P, O'Neal M, Hocker N. Improving the inter-laboratory harmonization of the international normalized ratio (INR): utilizing the concept of transference to estimate and/or validate international sensitivity index (ISI) and mean normal prothrombin time (MNPT) values and/or to eliminate measurement bias. Clin Lab Sci 2012; 25:13-25. [PMID: 22458045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
BACKGROUND The Prothrombin Time (PT) assay is clinically the most often requested coagulation test, as used primarily for monitoring of Vitamin K antagonist therapy where results are typically expressed as an International Normalized Ratio (INR). The INR reflects the patient's PT adjusted for the specific test reagent and instrument combination used by applying two correction factors, namely the International Sensitivity Index (ISI) and the Mean Normal Prothrombin Time (MNPT), according to the formula: INR = (patient PT/MNPT)ISI. When the manufacturer provides an ISI, laboratories are encumbered to check or locally validate the assigned value. Where a manufacturer does not provide an ISI, the laboratory needs to define its own (local ISI) value. The MNPT typically has to be locally defined, based on the population being tested. The main current CLSI recommendation for defining ISI values comprises use of commercial reference ('certified') plasma calibration sets, but FDA cleared material is limited, and different results may arise using different products. The MNPT can be defined using a WHO/CLSI recommended procedure requiring 20 normal individuals or with some calibration sets. Overall, there is limited data to validate the performance of these processes in laboratory practice, and ongoing evidence from external quality assurance (proficiency testing) programs indicates continued failure in INR harmonization, suggesting that ISI and MNPT values used by laboratories (and presumably assessed using current recommended processes) continue to be inaccurate. OBJECTIVE To assess some novel approaches to the laboratory estimation and/or validation of ISI and MNPT values for use in the INR calculation, and including the process of 'transference', normally used to assess the comparability of analytical systems or to transfer reference intervals between comparable systems. RESULTS We have successfully adapted these comparative procedures, including 'transference', to permit ongoing estimation and/or validation of ISI and MNPT values for use in INR calculations for a range of instrumentation, which has led to improved harmonization of INR values obtained in our pathology network. These processes do not require the use of any normal individual plasmas or calibrator sets and greatly simplifies the INR process. Evidence for validation of the processes used is provided by ongoing satisfactory performance in external quality assurance (proficiency testing).
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Affiliation(s)
- Emmanuel J Favaloro
- Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead.
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Abstract
BACKGROUND The lipoglycopeptide antibiotic, telavancin, may interfere with some laboratory coagulation tests including prothrombin time (PT) and activated partial thromboplastin time (aPTT). OBJECTIVE To evaluate the effects of telavancin on PT and aPTT assays in common use. METHODS Pooled normal human plasma was spiked with telavancin 10, 20, 100 or 200 μg/ml (equivalent to trough, 2 × trough, peak and 2 × peak clinical plasma concentrations, respectively) or diluent control (0.9% sodium chloride). Samples were analysed using 16 PT reagents and seven aPTT reagents. RESULTS Telavancin 200 μg/ml (corresponding to 2 × peak clinical plasma concentration), produced significant PT prolongation (> 9% difference vs. diluent control) with all the 16 PT reagents (range 12% to > 600%). At lower telavancin concentrations, PT prolongation was dose-dependent and varied among reagents, but appeared greatest with preparations containing recombinant tissue factor. With telavancin 10 μg/ml (equivalent to trough), PT prolongation was 10% with HemosIL(®) PT-Fibrinogen Recombinant, while ranging from 5% to -1% with all other reagents. Significant (> 34% difference vs. baseline) and dose-dependent aPTT prolongation was observed with all the seven reagents in samples spiked with telavancin 100 or 200 μg/ml (range 65-142% at 200 μg/ml). aPTT reagents containing a silica activator appeared to be more sensitive to telavancin interference. Telavancin 10 μg/ml was not associated with increased aPTT with any of the reagents tested. CONCLUSIONS Telavancin has the potential to prolong both PT and aPTT in vitro. It is recommended that samples for PT or aPTT be obtained just prior to a telavancin dose (trough).
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Affiliation(s)
- S L Barriere
- Theravance, Inc., South San Francisco, CA 94080, USA.
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Berkovskiĭ AL, Sergeeva EV, Kachalova ND, Gurvits ID, Suvorov AV, Ul'ianova IS, Ivanov IG, Kozlov AA. [Assessment of thromboplastins according to the WHO guidelines and the results of external quality control]. Klin Lab Diagn 2011:30-33. [PMID: 21735677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The study was undertaken to assess commercial thromboplastins for compliance to the WHO guidelines and to substantiate the validity of the results of a prothrombin test carried out using these thromboplastins. The test thromboplastins were shown to meet the WHO guidelines for assessment of thromboplastins. Over 5-8 years of the authors'participation in two external quality control programs (Federal External Quality Control System, Russia; 72 trials; NEQAS, United Kingdom; 60 trials), the international normalized ratio derived through the use of assessed thromboplastins did not differ from that established due to the interlaboratory consensus value of both external quality control systems. It is concluded that correct thromboplastin assessment provide accurate results of determination of prothrombin time.
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Tripodi A, Chantarangkul V, Guinet C, Samama MM. The International Normalized Ratio calibrated for rivaroxaban has the potential to normalize prothrombin time results for rivaroxaban-treated patients: results of an in vitro study. J Thromb Haemost 2011; 9:226-8. [PMID: 20942848 DOI: 10.1111/j.1538-7836.2010.04106.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
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Poller L, Ibrahim S, Keown M, Pattison A, Jespersen J. The prothrombin time/international normalized ratio (PT/INR) Line: derivation of local INR with commercial thromboplastins and coagulometers--two independent studies. J Thromb Haemost 2011; 9:140-8. [PMID: 20942851 DOI: 10.1111/j.1538-7836.2010.04109.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND The WHO scheme for prothrombin time (PT) standardization has been limited in application, because of its difficulties in implementation, particularly the need for mandatory manual PT testing and for local provision of thromboplastin international reference preparations (IRP). METHODS The value of a new simpler procedure to derive international normalized ratio (INR), the PT/INR Line, based on only five European Concerted Action on Anticoagulation (ECAA) calibrant plasmas certified by experienced centres has been assessed in two independent exercises using a range of commercial thromboplastins and coagulometers. INRs were compared with manual certified values with thromboplastin IRP from expert centres and in the second study also with INRs from local ISI calibrations. RESULTS In the first study with the PT/INR Line, 8.7% deviation from certified INRs was reduced to 1.1% with human reagents, and from 7.0% to 2.6% with rabbit reagents. In the second study, deviation was reduced from 11.2% to 0.4% with human reagents by both local ISI calibration and the PT/INR Line. With rabbit reagents, 10.4% deviation was reduced to 1.1% with both procedures; 4.9% deviation was reduced to 0.5% with bovine/combined reagents with local ISI calibrations and to 2.9% with the PT/INR Line. Mean INR dispersion was reduced with all thromboplastins and automated systems using the PT/INR Line. CONCLUSIONS The procedure using the PT/INR Line provides reliable INR derivation without the need for WHO ISI calibration across the range of locally used commercial thromboplastins and automated PT systems included in two independent international studies.
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Affiliation(s)
- L Poller
- EAA Central Facility, Faculty of Life Sciences, University of Manchester, Manchester, UK.
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Tripodi A, Chantarangkul V, Van Den Besselaar AMHP, Witteveen E, Hubbard AR. International collaborative study for the calibration of a proposed international standard for thromboplastin, human, plain. J Thromb Haemost 2010; 8:2066-8. [PMID: 20626621 DOI: 10.1111/j.1538-7836.2010.03980.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- A Tripodi
- Angelo Bianchi Bonomi Hemophilia and Thrombosis Centre, Department of Internal Medicine, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico and Università degli Studi di Milano, Milan, Italy.
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Abstract
OBJECTIVE Adjusted-dose warfarin therapy can prevent stroke in patients with atrial fibrillation. However, the quality of the warfarin control may be considered to be important for elderly patients. methods: We followed 188 patients (age > or =70 years) with atrial fibrillation (warfarin, 120 patients; non-warfarin, 68 patients) for 2 years. Their warfarin control was assessed by time in therapeutic range (TTR) for an international normalized ratio of prothrombin time of 1.6-2.6, based on the Japanese guidelines of anticoagulation for elderly patients with atrial fibrillation. RESULTS Stroke occurred in 23 patients (12.2%). In warfarin-treated patients, receiver-operator characteristic (ROC) curves suggested that patients with TTR >68% had anticoagulation benefit. In the ROC curves for prediction of stroke, the area under the curve of TTR was 0.709 (95% confidence interval, 0.585 to 0.834; p=0.02). The sensitivity and specificity of TTR < or =68% were 91.7% and 54.0%, respectively. Kaplan-Meier curves showed that the event-free ratio of stroke was significantly higher in patients who achieved this cut-off of TTR. CONCLUSION The results suggest that the quality of warfarin control is directly associated with the incidence of stroke in elderly patients.
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Affiliation(s)
- Nobuyuki Masaki
- Department of Cardiology, National Defense Medical College, Tokorozawa, Japan.
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Sølvik UØ, Stavelin A, Christensen NG, Sandberg S. External quality assessment of prothrombin time: The split‐sample model compared with external quality assessment with commercial control material. Scandinavian Journal of Clinical and Laboratory Investigation 2009; 66:337-49. [PMID: 16777762 DOI: 10.1080/00365510600684580] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
OBJECTIVE CoaguChek S is a point-of-care, whole-blood, prothrombin time monitor. The purpose of this study was to compare two different methods for external quality assessments of CoaguChek S. MATERIAL AND METHODS In the traditional external quality assessment scheme, commercial control material was sent to office laboratories and the results were compared with a method-specific target value. In the alternative external quality assessment (the split-sample survey) patient samples were analyzed on CoaguChek S at office laboratories, and venous blood samples from the same patients were analyzed at a hospital laboratory using an assigned comparison method. To obtain comparable performance criteria for the two methods, the limits for "good", "acceptable" and "poor" performance evaluation in the split-sample survey had to be expanded because of uncertainties in preanalytical factors and the comparison method. RESULTS In the traditional external quality assessment the total imprecision (between-office and within-office) was 8.0% at the low level (1.6 INR (International Normalized Ratio)) and 10.5% at the therapeutic level (3.4 INR). In the split-sample survey the total imprecision was 12.3% at the low level (2.1 INR) and 10.7 % at the high level (3.0 INR). Seventy-five percent of the participating office laboratories were characterized as "good" with the traditional external quality assessments, whereas the corresponding number was 73% using the split-sample model. CONCLUSIONS Available commercial control material for CoaguChek S is different from patient samples. This study demonstrates that split-sample survey is achievable, and is an acceptable alternative to traditional external quality assessment for point-of-care prothrombin time monitors where appropriate control material is difficult to obtain.
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Affiliation(s)
- U Ø Sølvik
- Section for General Practice, Department of Public Health and Primary Health Care, Faculty of Medicine, University of Bergen, and the Norwegian Quality Improvement of Primary Care Laboratories (NOKLUS), Norway.
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Abstract
The current basis for deceased donor liver allocation is the Model for End-stage Liver Disease (MELD) score, which is an objective means of predicting 90-day patient survival. Although the MELD system is a vast improvement over the prior allocation scheme, published studies have refuted the United Network for Organ Sharing statement that "the MELD and PELD [Pediatric End-stage Liver Disease] formulas are simple, objective and verifiable and yield consistent results whenever the score is calculated." In particular, wide inter-laboratory variation exists in the most heavily weighted MELD determinant, the international normalized ratio (INR). Whether this variation impacts the equitable distribution of deceased donor livers is unclear. However, the current technique for measuring the INR has the potential to detract from the expressed purpose of MELD-based allocation, which is to prioritize liver transplant candidates across the country with parity, using an objective scoring system.
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Affiliation(s)
- Russ Arjal
- Division of Gastroenterology/Hepatology, University of Colorado Health Sciences Center, 1635 N. Ursula, B-154, Aurora, CO 80045, USA
| | - James F Trotter
- Division of Gastroenterology/Hepatology, University of Colorado Health Sciences Center, 1635 N. Ursula, B-154, Aurora, CO 80045, USA.
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Devreese K, Peerlinck K, Arnout J, Hoylaerts MF. Laboratory detection of the antiphospholipid syndrome via calibrated automated thrombography. Thromb Haemost 2009; 101:185-196. [PMID: 19132207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Lupus anticoagulants (LAC) consist of antiphospholipid antibodies, detected via their anticoagulant properties in vitro. Strong LAC relate to thromboembolic events, a hallmark of the antiphospholipid syndrome. We have analyzed whether detection of this syndrome would benefit from thrombin generation measurements. Therefore, calibrated automated thrombography was done in normal plasma (n = 30) and LAC patient plasma (n = 48 non-anticoagulated, n = 12 on oral anticoagulants), diluted 1:1 with a normal plasma pool. The anti-beta2-glycoprotein I monoclonal antibody 23H9, with known LAC properties, delayed the lag time and reduced the peak height during thrombin generation induction in normal plasma dose-dependently (0-150 microg/ml). At variance, LAC patient 1:1 plasma mixtures manifested variable lag time prolongations and/or peak height reductions. Coupling these two most informative thrombin generation parameters in a peak height/lag time ratio, and upon normalization versus the normal plasma pool, this ratio distributed normally and was reduced in the plasma mixtures, for 59/60 known LAC plasmas. The normalized peak height/lag time ratio correlated well with the normalized dilute prothrombin time, diluted Russell's viper venom time and silica clotting time, measured in 1:1 plasma mixtures (correlation coefficients 0.59-0.72). The anticoagulant effects of activated protein C (0-7.5 nM) or 23H9 (0-150 microg/ml), spiked in the 1:1 LAC plasma mixtures were reduced for the majority of patients, compatible with functional competition between patient LAC and activated protein C and LAC and 23H9, respectively. Hence, the normalized thrombin generation-derived peak height/lag time ratio identifies LAC in plasma with high sensitivity in a single assay, irrespective of the patient's treatment with oral anticoagulants.
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Affiliation(s)
- Katrien Devreese
- Coagulation Laboratroy, Department of Clinical Chemistry, Microbiology and Immunology, Ghent University Hospital, Ghent, Belgium
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Stavelin A, Omenås B, Bolann B, Christensen NG, Sandberg S. [Choice of PT-INR instruments in primary health care]. Tidsskr Nor Laegeforen 2008; 128:2620. [PMID: 19023367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
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Vladimirova SG, Tarasova LN. [Problems in the standardization of a prothrombin test (a review of literature)]. Klin Lab Diagn 2008:51-54. [PMID: 19069448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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Kitchen S, Kitchen D, Jennings I, Woods T, Walker I. External quality assessment of CoaguChek point-of-care testing prothrombin time/international ratio monitors. Am J Clin Pathol 2008; 129:825-826. [PMID: 18481407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
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Tripodi A. How to implement the modified international normalized ratio for cirrhosis (INR(liver)) for model for end-stage liver disease calculation. Hepatology 2008; 47:1423-4; author reply 1424. [PMID: 18306415 DOI: 10.1002/hep.21989] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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Braun SL. CoaguChek point-of-care testing prothrombin time monitors. Am J Clin Pathol 2007; 128:671-672. [PMID: 17924500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023] Open
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Bellest L, Eschwège V, Poupon R, Chazouillères O, Robert A. A modified international normalized ratio as an effective way of prothrombin time standardization in hepatology. Hepatology 2007; 46:528-34. [PMID: 17654598 DOI: 10.1002/hep.21680] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
UNLABELLED International Normalized Ratio (INR), which standardizes prothrombin time (PT) during oral anticoagulation, has been extended to standardize PT in liver diseases and is included in prognostic models such as the Model for End stage Liver Disease (MELD). However, mechanisms of PT prolongation in liver diseases differ from those involved in oral anticoagulation, and the thromboplastin reagents differ in their sensitivities to these 2 mechanisms. Our aim was to determine whether, in the calibration model for thromboplastins proposed by the World Health Organization, the use of plasmas from patients with liver diseases instead of plasmas from patients on oral anticoagulation could lead to a new INR specific for liver diseases (INR "LD"), achieving a real standardization of PT. First, 5 thromboplastins were calibrated against an international reference using 60 plasmas of patients with liver failure and, in a second step, the variation of PT reported as seconds, the ratio of patient PT to normal PT, INR, and INR"LD" was assessed in 34 other patients. MELD scores were calculated with the INR values obtained with the 5 thromboplastins. Only INR"LD" eliminated variability in PT results observed with the different thromboplastins. The discrepancy between MELD scores were up to 4 and 7 points in 52% and 17% of the patients, respectively. CONCLUSION INR "LD" may provide a common international scale of PT reporting in hepatology. Its adoption would be an important step because of the significant impact on MELD score induced by interlaboratory variability in INR determination.
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Affiliation(s)
- Laurent Bellest
- AP-HP, Hôpital St Antoine, Unité d'Hémostase, Université Pierre et Marie Curie, Paris, France
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Abstract
BACKGROUND Prothrombin time (PT)-derived international normalized ratio (INR) is used to assess bleeding risk and prognosis in cirrhosis, and to guide management of associated coagulation disturbances. Recent studies cast doubt on the validity of the assumptions that form the basis for these applications. AIMS To review and critique the use of the PT-INR in cirrhosis. METHODS Search of the literature. RESULTS In cirrhosis, there is a decrease in both pro- and anti-coagulants. The PT-INR measures only the activity of procoagulants and fails to capture changes in anticoagulants. It is therefore not surprising that the PT does not predict the bleeding risk. The PT-INR provides a robust measure of liver function but recent data showed INR inter-laboratory variability in this setting. This is not surprising as the INR was validated to normalize results for patients on vitamin-K antagonists, not for cirrhosis. This limitation was not appreciated, but the INR is used to construct the model for end-stage liver disease score to prioritize patients for liver transplantation. Reports showed that model for end-stage liver disease is modified by the thromboplastin used for testing. CONCLUSIONS Alternate tests to predict bleeding risk should be developed. The potential for misuse of the PT-INR should drive the development of alternate algorithms for organ allocation.
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Affiliation(s)
- A Tripodi
- Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, IRCCS Maggiore Hospital, Mangiagalli and Regina Elena Foundation, University of Milan, Milan, Italy.
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Morelli VM, Rodrigues CA, Noguti MAE, Matos MF, da Silveira RC, Ribeiro AAM, Lourenço DM. Performance of Platelin LS and dilute Russell's viper venom for the screening of lupus anticoagulant in patients with venous thromboembolism. Blood Coagul Fibrinolysis 2007; 18:401-5. [PMID: 17581313 DOI: 10.1097/mbc.0b013e32814fcc50] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Lupus anticoagulant is associated with thrombosis and pregnancy morbidity, and its detection is of major clinical importance. The nature and concentration of phospholipids strongly influence the sensitivity of activated partial thromboplastin time (aPTT) reagents to lupus anticoagulant. We investigated the ability of Platelin LS, an aPTT reagent, to screen lupus anticoagulant among 94 patients with venous thromboembolism by comparing its performance with the dilute Russell viper venom time (dRVVT). Twenty-four patients had an abnormal aPTT and dRVVT, whereas 37 only had a prolonged dRVVT. In users of oral anticoagulants (n = 56), the dRVVT prolonged more frequently than the aPTT (98.2 vs 39.3%, P < 0.0001). After the mixing study, seven patients maintained abnormal aPTT and dRVVT ratios, five of whom had prolonged mixture with both tests. The agreement in the mixing study between aPTT and dRVVT was substantial (kappa = 0.78, 95% confidence interval = 0.48-1.00). Except for one patient, the aPTT screened all cases that demonstrated phospholipid dependency of their inhibitor during the confirmatory procedure with the dRVVT. In conclusion, the aPTT using Platelin LS was highly associated with the presence of lupus anticoagulant detected by the dRVVT among patients with venous thromboembolism, and could be reliably employed as a screening assay for lupus anticoagulant.
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Affiliation(s)
- Vânia Maris Morelli
- Division of Hematology and Transfusion Medicine, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil.
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Aframian DJ, Lalla RV, Peterson DE. Management of dental patients taking common hemostasis-altering medications. ACTA ACUST UNITED AC 2007; 103 Suppl:S45.e1-11. [PMID: 17379154 DOI: 10.1016/j.tripleo.2006.11.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Accepted: 11/09/2006] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Millions of patients worldwide are taking medications that alter hemostasis and decrease the risk for thromboembolic events. This systematic review is intended to provide recommendations regarding optimal management of such patients undergoing invasive dental procedures. The primary focus of this report is on warfarin therapy, although issues related to heparin and aspirin are briefly discussed because of the frequency with which they are encountered in dental practice. STUDY DESIGN The review of literature and development of recommendations was based on the Reference Manual for Management Recommendations for the World Workshop in Oral Medicine IV (WWOM IV). A total of 64 publications were identified for initial review. From these publications, the following types of articles were critically analyzed using WWOM standard forms: randomized controlled trials (RCT), non-RCT studies that assess effects of interventions, and studies that assess modifiable risk factors. Development of recommendations was based on the findings of these reviews as well as expert opinion. RESULTS The following evidence-based recommendations were developed: (1) For patients within the therapeutic range of International Normalized Ratio (INR) below or equal to 3.5, warfarin therapy need not be modified or discontinued for simple dental extractions. Nevertheless, the clinician's judgment, experience, training, and accessibility to appropriate bleeding management strategies are all important components in any treatment decision. Patients with INR greater than 3.5 should be referred to their physician for consideration for possible dose adjustment for significantly invasive procedures. (2) A 2-day regimen of postoperative 4.8% tranexamic acid mouthwash is beneficial after oral surgical procedures in patients on warfarin. (3) It is not necessary to interrupt low-dose aspirin therapy (100 mg/day or less) for simple dental extractions. CONCLUSION For most patients undergoing simple single dental extractions, the morbidity of potential thromboembolic events if anticoagulant therapy is discontinued clearly outweighs the risk of prolonged bleeding if anticoagulant therapy is continued.
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Affiliation(s)
- Doron J Aframian
- Salivary Gland Clinic and Residency Program, The Hebrew University, Hadassah School of Dental Medicine, Jerusalem, Israel
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van den Besselaar AMHP, Hoekstra MMCL, Witteveen E, Didden JH, van der Meer FJM. Influence of blood collection systems on the prothrombin time and international sensitivity index determined with human and rabbit thromboplastin reagents. Am J Clin Pathol 2007; 127:724-9. [PMID: 17439830 DOI: 10.1309/nw194eamd4wmehjd] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Three brands of blood collection tubes were studied for their influence on the prothrombin time (PT) and international sensitivity index (ISI) for 5 commercial thromboplastin reagents. With all reagents, PTs were shorter in Vacutainer (Becton Dickinson Vacutainer Systems, Plymouth, England) samples than in S-Monovette (Sarstedt, Nümbrecht, Germany) or Venosafe (Terumo Europe, Leuven, Belgium) samples. ISI values were higher with Vacutainer samples than with S-Monovette or Venosafe samples. The ISI differences between the tubes were small for Thromborel-S (2.1%; Dade Behring, Marburg, Germany) and Hepato Quick (1.1%; Diagnostica Stago, Asnières, France; Roche Diagnostics Nederland, Almere, the Netherlands) but greater for Neoplastin Plus (5.5%; Diagnostica Stago; Roche Diagnostics Nederland), Simplastin HTF (8.3%; bioMérieux, Durham, NC), and Innovin (8.8%; Dade Behring). The PT and ISI differences between the tubes could be explained mostly by the effect of magnesium ion contamination in the sodium citrate solutions. When PT ratios were transformed into international normalized ratios (INRs) using crossover ISI (ie, samples collected with one type of tube and ISI determined with another collection system for the PT reagent), the differences in mean INRs could be approximately 10%. For ISI calibration of reference thromboplastins, blood collection tubes should be used with minimal divalent metal ion contamination of the citrate solution.
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Affiliation(s)
- Anton M H P van den Besselaar
- Hemostasis and Thrombosis Research Center, Department of Hematology, Leiden University Medical Center, Leiden, The Netherlands
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Abstract
AIM To compare prothrombin time and activated partial thromboplastin time values in concurrent blood samples obtained by direct venipuncture and from a peripheral venous catheter. METHOD Concurrent blood samples obtained from catheters and by direct venipuncture were studied. Venipuncture samples were labelled as the reference (control) group and the peripheral venous catheter samples as the experimental group. A 21-gauge needle was used in the venipuncture method and 18G, 20G, 22G catheters were used in the peripheral venous catheters method. In each case, after the blood samples were drawn by venipuncture and peripheral venous catheter the needles were drawn out, 1.8 ml of blood was added to 0.2 ml of citrate to give a 2 ml sample. The tube was shaken gently to mix the blood and citrate well. RESULTS No clinically significant difference between prothrombin time and activated partial thromboplastin time values were seen in the blood samples drawn by venipuncture and peripheral venous catheter methods. DISCUSSION It is recommended that peripheral venous catheter can be used for patients with high bleeding risk if they have a long hospital stay and frequent blood samples are needed. RELEVANCE TO CLINICAL PRACTICE In clinical applications, nurses may prefer the use of peripheral venous catheter to venipuncture both for the comfort of the patients who get anticoagulation therapy and for the prevention of the risks as a result of venipuncture. Application of peripheral venous catheter eliminates the risks of superficial bleeding, irritation, pain and anxiety caused by venipuncture.
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Affiliation(s)
- Neriman Zengin
- Bakirkoy Health School, Istanbul University, Istanbul, Turkey.
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van den Besselaar AMHP, Hoekstra MMCL, van der Meer FJM. Quality control of CoaguChek test strips in the Netherlands. Thromb Haemost 2007; 97:323-4. [PMID: 17264967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
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Meijer P, Kluft C, Poller L, van der Meer FJM, Keown M, Ibrahim S, van den Besselaar AMHP, Tripodi A, Jespersen J. A national field study of quality assessment of CoaguChek point-of-care testing prothrombin time monitors. Am J Clin Pathol 2006; 126:756-61. [PMID: 17050073 DOI: 10.1309/6q8d-y5j1-tha8-bqg3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2022] Open
Abstract
A system for quality assessment (QA) of the CoaguChek (Roche Diagnostics, Mannheim, Germany) point-of-care testing prothrombin time monitor has been developed by the European Concerted Action on Anticoagulation. Hitherto there has not been an adequate rapid method for CoaguChek QA. Sets of 5 certified international normalized ratio (INR) plasma samples were tested on 539 CoaguChek monitors by experienced staff at 9 Netherlands Thrombosis Centers and results compared with certified INR. A 15% or more deviation has been classified as significant deviation. Overall mean and certified INR values were similar, but 20.3% of participants showed a 15% or more deviation from the certified INR on at least 1 of the 5 QA plasma samples. Statistically significant differences in results with different lots of CoaguChek test strips were found. There is need for large scale QA of CoaguChek monitors. The importance of the 5 CoaguChek certified INR QA plasma samples being tested on a single occasion is demonstrated.
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Affiliation(s)
- Piet Meijer
- European Concerted Action on Thrombosis (ECAT) Foundation, Leiden, the Netherland
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Berkovsky A, Sergeeva EV, Suvorov AV, Uljavova IS, Kachalova ND, Klimovich LG, Samsonova NN, Kozlov AA. A modified method of prothrombin time/International Normalised Ratio determination in capillary blood and monitoring oral anticoagulant therapy. Clin Chem Lab Med 2006; 44:1214-7. [PMID: 17032133 DOI: 10.1515/cclm.2006.217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Oral anticoagulant therapy is monitored by a prothrombin time (PT) assay. The PT is standardised by the International Normalised Ratio (INR). The purpose of this study was to work out a modified method of PT/INR measurement in capillary blood for monitoring anticoagulation treatment. METHODS Healthy donors, subjects with high or low haematocrit values, and oral anticoagulant-treated patients were included in the study. Plasma and capillary blood PT/INRs were determined by the standard Quick clotting assay, by the modified approach and with the CoaguChek S analyser. RESULTS The performance characteristics of the developed method were accuracy, due to taking into account whole capillary blood haematocrit values, and precision, due to a decrease in the viscosity of the analysed samples. Implementation of the modified method showed that it is possible to use PT values of normal plasma for capillary blood INR calculation. The developed method allowed the determination of PT in capillary blood within the haematocrit value range from 0.15 up to 0.7. For capillary blood, the results of the modified method closely correlated with PT/INR values determined by the reference Quick method in venous plasma (r=0.99) and with the CoaguChek S analyser (r=0.97). CONCLUSIONS The modified method of capillary blood PT/INR determination could be recommended for oral anticoagulant therapy monitoring.
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Affiliation(s)
- Aron Berkovsky
- Institute of Blood Transfusion, Scientific Research Centre of Haematology, Moscow, Russia.
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Scolaro KL, Stamm PL, Lloyd KB. Devices for ambulatory and home monitoring of blood pressure, lipids, coagulation, and weight management, part 2. Am J Health Syst Pharm 2006; 62:1894-903. [PMID: 16141109 DOI: 10.2146/ajhp040346.p2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PURPOSE The equipment and methods used for ambulatory and home monitoring of blood pressure, lipids, coagulation, and weight management are discussed. SUMMARY Over 100 million people in the United States have one or more chronic diseases, such as diabetes, hypertension, and asthma. With the goal to improve health while reducing costs and the overall health care burden, ambulatory and home monitoring by pharmacists and patients are receiving more attention. Ambulatory and home monitoring of blood pressure, cholesterol, coagulation, and weight management (including devices for assessing overweight and obese patients, heart rate monitors, and pedometers) are convenient for clinicians and patients. Such monitoring provides pharmacists with an opportunity to differentiate their practices. Studies suggest that patients who are involved in ambulatory and home monitoring take a more active role in their health and may have better adherence to a prescribed diet and medication regimens. Studies also show that ambulatory and home monitoring, if done correctly, provide clinicians with a large quantity of reliable readings for future therapeutic decisions. Devices are also a means for pharmacists to increase their provision of pharmacy services. Ambulatory monitoring is billable in many clinic settings, and the devices can be a profitable addition to prescription services. CONCLUSION Many devices are available to assist patients and clinicians in monitoring blood pressure, lipids, coagulation, and weight management. Familiarity with the devices will help in their proper selection and use.
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Linsinger TPJ, van den Besselaar AMHP, Tripodi A. Long-term stability of relationships between reference materials for thromboplastins. Thromb Haemost 2006; 96:210-4. [PMID: 16894466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Reference materials for thromboplastins are available from the World Health Organization (WHO) and the European Commission (EC). The long-term stability of the reference materials is an essential requirement and must be monitored. The relationship between two reference materials for rabbit thromboplastin, i.e. ERM-AD149 (EC) and RBT/90 (WHO), has been monitored in the period 1996-2002. No significant trend with time was detected. In addition, the relationship between ERM-AD149 and the reference material for bovine thromboplastin (i.e. OBT/79) has been determined in 1994 and in 2005 in multicentre studies (n = 11 and n = 9, respectively). No significant changes were observed in the relationships between these reference materials when all results were included (5% significance level).
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Abstract
BACKGROUND Thromboplastin reagents are used to conduct prothrombin time (PT) clotting tests to monitor oral anticoagulant therapy and screen for clotting factor deficiencies. Thromboplastins made from purified, recombinant tissue factor are generally more sensitive to changes in plasma factor (F) VII levels than are thromboplastins prepared from tissue extracts. This may be problematic as FVII's short plasma half-life can result in day-to-day fluctuation during oral anticoagulant therapy. We hypothesized that trace contamination of tissue-derived thromboplastins with FVII(a) blunts sensitivity to plasma FVII levels. METHODS Traces of purified FVIIa were added to thromboplastin reagents prepared using recombinant human tissue factor and the effect on sensitivity to individual clotting factors was quantified in PT clotting assays. RESULTS AND CONCLUSIONS Adding 5-100 pm FVIIa not only decreased thromboplastin sensitivity to plasma FVII, it surprisingly increased sensitivity to plasma levels of FV, FX and prothrombin. In addition, traces of FVIIa interacted with changes in the salt content and phospholipid composition of recombinant thromboplastins to further modulate their sensitivities to individual clotting factors. These results help explain how thromboplastin reagents of differing composition exhibit differing sensitivities to individual clotting factor levels. Implications of our results for monitoring oral anticoagulant therapy and other uses of the PT assay are discussed.
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Affiliation(s)
- S A Smith
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 506 S. Mathews, Urbana, IL 61801, USA
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Chantarangkul V, van den Besselaar AMHP, Witteveen E, Tripodi A. International collaborative study for the calibration of a proposed international standard for thromboplastin, rabbit, plain. J Thromb Haemost 2006; 4:1339-45. [PMID: 16706980 DOI: 10.1111/j.1538-7836.2006.01910.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND A preparation of rabbit brain thromboplastin, provisionally coded 04/162, is proposed as a candidate for the World Health Organization (WHO) International Standard (IS) for thromboplastin (rabbit, plain), meant to replace the IS coded RBT/90 (rabbit, plain), stocks of which are now exhausted. RESULTS The preparation was calibrated in an international collaborative study involving 21 laboratories from 13 countries and the calibration was performed against the existing WHO-IS (i.e. rTF/95 and OBT/79) and other Certified Reference Materials from the Institute for Reference Materials and Measurements of the European Commission (i.e. CRM149 S) and from the European Action on Anticoagulation (i.e. EUTHR-01). An additional candidate rabbit brain thromboplastin coded as 04/106 was also included in the study. On the basis of predefined criteria (the within- and between-laboratory precision of the calibration and the conformity to the calibration model), 04/162 was the preferred candidate. CONCLUSIONS The assigned International Sensitivity Index value was 1.15 and the inter-laboratory SD and coefficient of variation were 0.057% and 4.9%, respectively.
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Affiliation(s)
- V Chantarangkul
- Department of Internal Medicine, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, University and IRCCS Ospedale Maggiore, Mangiagalli and Regina Elena Foundation, Milan, Italy
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Mischke R, Junker J, Deegen E. Sensitivity of commercial prothrombin time reagents to detect coagulation factor deficiencies in equine plasma. Vet J 2006; 171:114-9. [PMID: 16427588 DOI: 10.1016/j.tvjl.2004.09.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/18/2004] [Indexed: 11/16/2022]
Abstract
The sensitivity of commercial prothrombin time (PT) tests was assessed based on a dilution series of equine pooled plasma (EPP) (experiment 1) and on 40 equine plasma samples with reduced activity of coagulation factors II, V, VII and X (experiment 2). Two different PT reagents (reagent 1, human placental thromboplastin; reagent 2, recombinant human tissue factor) were used according to the manufacturers' instructions (standard test, PT([ST])) and compared to a modified test procedure (modified test, PT([MT])) using sample dilution and fibrinogen addition. In all samples, sensitivity was lower (P<0.01) when using PT([ST]) with reagent 2 (0.20) than when using either PT([ST]) with reagent 1 (0.65) or PT([MT]) with both reagents (reagent 1, 0.60-0.75, reagent 2, 0.58-0.70, depending on sample dilution). The highest sensitivity was found for PT([MT]) when using a 1:20 sample dilution. In those samples in which at least one coagulation factor activity was decreased (by 20%; n=18), the sensitivity of PT([ST]) with reagent 2 (0.33) was found to be inadequate, in contrast to all other test procedures (0.83-0.94). This low sensitivity corresponded to shorter time intervals between different coagulation activity levels prepared by EPP dilution. The results indicate that adequate sensitivity of PT measurements in equine plasma can be achieved using a standard test procedure as long as a suitable reagent is used.
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Affiliation(s)
- R Mischke
- Small Animal Clinic, Hannover School of Veterinary Medicine, Bischofsholer Damm 15, D-30173 Hannover, Germany.
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Abstract
Preanalytical variability is a common source of errors in coagulation testing, as clotting assays are particularly susceptible to poor standardization of the whole analytical process. To investigate the effect of a short-term venous stasis on routine coagulation testing, we measured activated partial thromboplastin time, prothrombin time, fibrinogen and D-dimer in plasma specimens collected either without venous stasis or following the application of a 60 mmHg constant, standardized external pressure by a sphygmomanometer, for 1 (1-min stasis) and 3 min (3-min stasis). When compared with blood specimens collected without stasis, the Pearson's correlation coefficients and the corresponding slopes of the Passing and Bablok regression line of samples collected following 1 and 3-min stasis were acceptable. However, statistically significant differences by paired Student's t-test could be observed for all parameters tests following 3-min stasis, and for all but the activated partial thromboplastin time after 1-min stasis. Significant difference between specimens collected after 1- and 3-min stasis was also achieved for prothrombin time (P < 0.01), fibrinogen (P < 0.01) and D-dimer (P < 0.05). The agreement between measurements was yet acceptable after 1-min stasis, but achieved clinical significance for prothrombin time, fibrinogen and D-dimer after 3-min stasis. Taken together, results of the present investigation confirm that the effects of venous stasis during venipuncture are clinically meaningful. As hematocrit values and activities of clotting factors VII, VIII and XII significantly increased, whereas that of activated factor VII remained unchanged, we hypothesize that a short-term venous stasis, as induced by up to 3-min tourniquet placing, might not be sufficient to produce additional procoagulant responses besides hemoconcentration.
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Affiliation(s)
- Giuseppe Lippi
- Department of Morphological and Biomedical Science, Clinical Chemistry Institute, University of Verona, Italy.
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