Quality control in the Netherlands; todays practices and starting points for guidance and future research

OBJECTIVES

Adequate analytical quality of reported results is primarily ensured by performing internal quality control (iQC). Currently, several different iQC practices are in use. As a prelude to the revision of a Dutch guidance document on analytical QC, a questionnaire was sent out to gain insights in the applied practices and the need for guidance.

METHODS

A questionnaire, containing 20 multiple-choice questions with possibilities for explanation and comment on iQC practices and aspects was distributed to all clinical chemistry laboratories within the Netherlands. Results were reported descriptively.

RESULTS

Responses were received from 27 clinical laboratories (response 43 %). In 30 % the iQC was based on the analytical characteristics only, while 30 % used a 6-Sigma method, 19 % risk-based beyond 6-Sigma and 22 % used an alternative approach. 89 % of laboratories used a virtual analyzer model for iQC setup within one or more laboratory sites. Practices for determining standard deviation (SD) values included determining SD for each new iQC material (35 %), using historical SD values for new materials (35 %), and incorporating clinical tolerances into the SD value (31 %). Furthermore, 44 % of laboratories used patient moving averages for one or more tests. Daily iQC management was based on either "traffic lights" indicating in or out of control status, and review of all QC charts, often using multiple software systems.

CONCLUSIONS

A large heterogeneity of iQC practices in clinical laboratories was observed in the Netherlands. Several starting points for further research and/or guidance were identified, particularly in relation to the determination of SD values, the virtual analyzer model and methods to ensure analyzer equivalence.

Quality standards and internal quality control practices in medical laboratories: an IFCC global survey of member societies

OBJECTIVES

The trueness and precision of clinical laboratory results are ensured through total quality management systems (TQM), which primarily include internal quality control (IQC) practices. However, quality practices vary globally. To understand the current global state of IQC practice and IQC management in relation to TQM the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Task Force on Global Laboratory Quality (TF-GLQ) conducted a survey of IFCC member countries on IQC practices and management.

METHODS

The survey included 16 questions regarding IQC and laboratory TQM practices and was distributed to IFCC full and affiliate member countries (n=110). A total of 46 (41.8 %) responses were received from all regions except North America.

RESULTS

Of the responding countries, 78.3 % (n=36) had legislative regulations or accreditation requirements governing medical laboratory quality standards. However, implementation was not mandatory in 46.7 % (n=21) of responding countries. IQC practices varied considerably with 57.1 % (n=28) of respondents indicating that they run 2 levels of IQC, 66.7 % (n=24) indicating they run IQC every 24 h and 66.7 % (n=28) using assay manufacturer IQC material sources. Only 29.3 % (n=12) of respondents indicated that every medical laboratory in their country has written IQC policies and procedures. By contrast, 97.6 % (n=40) of responding countries indicated they take corrective action and result remediation in the event of IQC failure.

CONCLUSIONS

The variability in TQM and IQC practices highlights the need for more formal programs and education to standardize and improve TQM in medical laboratories.

Interobserver Variability in Semen Analysis: Findings From a Quality Control Initiative

Introduction For laboratory tests, precision and accuracy are indispensable to ensure reliable results for both clinical diagnosis and research endeavors. The accuracy and reliability of results are important because they have an impact on both patient management and research. In this study, we evaluated the inter-observer variability between a trained technician and two academic residents, which acted both as a quality control measure as well as an assessment of training outcomes. Material and methods Freshly obtained semen samples from 28 subjects coming to the andrology laboratory were used. Semen analysis was performed by a regular technician permanently posted in the laboratory and two residents on completion of their posting in the andrology laboratory. All three examined the same sample after liquefaction for assessment of sperm motility, sperm concentration, sperm vitality, and sperm morphology. Semen analysis was done as per the recommendations of the WHO. Results The results of the study are presented as a coefficient of variation (CV), S charts, and Bland-Altman plot where we evaluated the interobserver variability in parameters on semen analysis of the same sample by three different assessors. The mean CV for sperm concentration across the samples was 6.24%. For sperm vitality, sperm morphology, and sperm motility the mean CV was 10.14%, 2.66%, and 8.11%, respectively. The S chart and Bland-Altman plot found a few random errors in measurements. Conclusion Regular quality control assessments are essential and should be implemented in andrology laboratories to ensure accurate and reliable results. Proper training of laboratory personnel is also vital for consistent outcomes. Other measures such as equipment calibration, use of high-quality reagents, and standard reporting are also crucial for the best results from a laboratory.

Comparison of Sigma metrics computed by three bias estimation approaches for 33 chemistry and 26 immunoassay analytes

Objectives

Sigma metric can be calculated using a simple equation. However, there are multiple sources for the elements in the equation that may produce different Sigma values. This study aimed to investigate the importance of different bias estimation approaches for Sigma metric calculation.

Methods

Sigma metrics were computed for 33 chemistry and 26 immunoassay analytes on the Roche Cobas 6000 analyzer. Bias was estimated by three approaches: (1) averaging the monthly bias values obtained from the external quality assurance (EQA) studies; (2) calculating the bias values from the regression equation derived from the EQA data; and (3) averaging the monthly bias values from the internal quality control (IQC) events. Sigma metrics were separately calculated for the two levels of the IQC samples using three bias estimation approaches. The resulting Sigma values were classified into five categories considering Westgard Sigma Rules as ≥6, <6 and ≥5, <5 and ≥4, <4 and ≥3, and <3.

Results

When classifying Sigma metrics estimated by three bias estimation approaches for each assay, 16 chemistry assays at the IQC level 1 and 2 were observed to fall into different Sigma categories under at least one bias estimation approach. Similarly, for 12 immunoassays at the IQC level 1 and 2, Sigma category was different depending on bias estimation approach.

Conclusions

Sigma metrics may differ depending on bias estimation approaches. This should be considered when using Six Sigma for assessing analytical performance or scheduling the IQC events.

Development and Implementation of an Internal Quality Control Sample to Standardize Oligomer-Based Diagnostics of Alzheimer's Disease

Protein misfolding and aggregation are pathological hallmarks of various neurodegenerative diseases. In Alzheimer's disease (AD), soluble and toxic amyloid-β (Aβ) oligomers are biomarker candidates for diagnostics and drug development. However, accurate quantification of Aβ oligomers in bodily fluids is challenging because extreme sensitivity and specificity are required. We previously introduced surface-based fluorescence intensity distribution analysis (sFIDA) with single-particle sensitivity. In this report, a preparation protocol for a synthetic Aβ oligomer sample was developed. This sample was used for internal quality control (IQC) to improve standardization, quality assurance, and routine application of oligomer-based diagnostic methods. We established an aggregation protocol for Aβ1-42, characterized the oligomers by atomic force microscopy (AFM), and assessed their application in sFIDA. Globular-shaped oligomers with a median size of 2.67 nm were detected by AFM, and sFIDA analysis of the Aβ1-42 oligomers yielded a femtomolar detection limit with high assay selectivity and dilution linearity over 5 log units. Lastly, we implemented a Shewhart chart for monitoring IQC performance over time, which is another important step toward quality assurance of oligomer-based diagnostic methods.

Internal quality control - past, present and future trends

Objectives

This paper offers an historical view, through a summary of the internal quality control (IQC) models used from second half of twentyth century to those performed today and wants to give a projection on how the future should be addressed.

Methods

The material used in this work study are all papers collected referring IQC procedures. The method used is the critical analysis of the different IQC models with a discussion on the weak and the strong points of each model.

Results

First models were based on testing control materials and using multiples of the analytical procedure standard deviation as control limits. Later, these limits were substituted by values related with the intended use of test, mainly derived from biological variation. For measurands with no available control material methods based on replicate analysis of patient' samples were developed and have been improved recently; also, the sigma metrics that relates the quality desired with the laboratory performance has resulted in a highly efficient quality control model. Present tendency is to modulate IQC considering the workload and the impact of analytical failure in the patent harm.

Conclusions

This paper remarks the strong points of IQC models, indicates the weak points that should be eliminated from practice and gives a future projection on how to promote patient safety through laboratory examinations.

Practical application of European biological variation combined with Westgard Sigma Rules in internal quality control

OBJECTIVES

Westgard Sigma Rules is a statistical tool available for quality control. Biological variation (BV) can be used to set analytical performance specifications (APS). The European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) regularly updates BV data. However, few studies have used robust BV data to determine quality goals and design a quality control strategy for tumor markers. The aim of this study was to derive APS for tumor markers from EFLM BV data and apply Westgard Sigma Rules to establish internal quality control (IQC) rules.

METHODS

Precision was calculated from IQC data, and bias was obtained from the relative deviation of the External quality assurance scheme (EQAS) group mean values and laboratory-measured values. Total allowable error (TEa) was derived using EFLM BV data. After calculating sigma metrics, the IQC strategy for each tumor marker was determined according to Westgard Sigma Rules.

RESULTS

Sigma metrics achieved for each analyte varied with the level of TEa. Most of these tumor markers except neuron-specific enolase reached 3σ or better based on TEa_min. With TEa_des and TEa_opt set as the quality goals, almost all analytes had sigma values below 3. Set TEa_min as quality goal, each analyte matched IQC muti rules and numbers of control measurements according to sigma values.

CONCLUSIONS

Quality goals from the EFLM BV database and Westgard Sigma Rules can be used to develop IQC strategy for tumor markers.

Quality in laboratory medicine and the Journal: walking together

Quality in laboratory medicine is defined as "an unfinished journey", as the more essential the laboratory information provided, the more assured its quality should be. In the past decades, the Journal Clinical Chemistry and Laboratory Medicine has provided a valuable forum for garnering new insights into the analytical and extra-analytical phases of the testing cycle, and for debating crucial aspects of quality in clinical laboratories. The impressive number of papers published in the Journal is testimony to the efforts made by laboratory professionals, national and international scientific societies and federations in the quest to continuously improve upon the pre-, intra- and post-analytical steps of the testing cycle, thus enhancing the quality of laboratory information. The paper appearing in this special issue summarizes the most important and interesting contributions published in the Journal, thus updating our knowledge on quality in laboratory medicine and offering further stimuli to identify the most valuable measures of quality in clinical laboratories.

Verification of examination procedures for 72 biochemical parameters on the atellica® clinical chemistry and immunoassay analyzers

The verification of examination procedures is a responsibility for clinical laboratories in order to guarantee that their performance characteristics comply with the specifications obtained during the validation process and are congruent with the intended scope of the assay. The aim was to perform an evaluation of precision, bias, linearity, linear drift, sample carry-over, and comparability of 73 assays from Siemens Healthineers, by following the CLSI EP10-A3 guidelines. The verification was performed by measuring 72 biochemical parameters in quality control (QC) materials from Bio-Rad (except for IL6) with 73 assays installed on eight measuring systems (five Atellica^® CH 930 and three IM 1600 analyzers from Siemens Healthcare Diagnostics). The following information was collected: validation data from manufacturer, biological variation data from the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) database, and specifications for fβhCG and PAPP-A assays to meet the Fetal Medicine Foundation standards. A total of 17550 results were obtained during EP10 verification process. Out of the 73 methods, only Cl-S, Mg-S, and Na-S failed the criteria for adequate precision, trueness, and comparability. The assays did not show significant loss of linearity, linear drift, or sample carry-over. This study allowed the initial training and familiarization with the instruments and the identification of operational issues. It also represented an opportunity to evaluate the QCs and to obtain analytical performance information for application of sigma six metrics for quality assurance. Professionals are advised to adequately standardize and protocolize their verification processes to ensure laboratory competence and patient safety.

Searching for the urine osmolality surrogate: an automated machine learning approach

OBJECTIVES

Automated machine learning (AutoML) tools can help clinical laboratory professionals to develop machine learning models. The objective of this study was to develop a novel formula for the estimation of urine osmolality using an AutoML tool and to determine the efficiency of AutoML tools in a clinical laboratory setting.

METHODS

Three hundred routine urinalysis samples were used for reference osmolality and urine clinical chemistry analysis. The H2O AutoML engine completed the machine learning development steps with minimum human intervention. Four feature groups were created, which include different urinalysis measurements according to the Boruta feature selection algorithm. Method comparison statistics including Spearman correlation, Passing-Bablok regression analysis were performed, and Bland Altman plots were created to compare model predictions with the reference method. The minimum allowable bias (24.17%) from biological variation data was used as the limit of agreement.

RESULTS

The AutoML engine developed a total of 183 ML models. Conductivity and specific gravity had the highest variable importance. Models that include conductivity, specific gravity, and other urinalysis parameters had the highest R² (0.70-0.83), and 70-84% of results were within the limit of agreement.

CONCLUSIONS

Combining urinary conductivity with other urinalysis parameters using validated machine learning models can yield a promising surrogate. Additionally, AutoML tools facilitate the machine learning development cycle and should be considered for developing ML models in clinical laboratories.

Internal quality control for HIV testing of blood donors - Dried tube specimen as a cost-effective alternative

BACKGROUND

An important aspect of ensuring blood safety is the performance of mandatory serological testing for transfusion transmissible infections. The practice of internal quality control (IQC) in blood banks in India is nonuniform, especially the use of third-party materials. Cited reasons are cost, lack of access to control materials, and need for deep-freezers for storage, if prepared in-house.

OBJECTIVE

Validation of dried tube specimen (DTS) from HIV-positive plasma as a low-cost, stable material for use as IQC material in blood banks.

METHODS

Fresh-frozen plasma (FFP) prepared from four HIV-positive blood-donors were pooled. Equal numbers of seronegative FFPs were pooled. Twenty microlitre aliquots of plasma were made in micro-centrifuge tubes and air-dried overnight at room-temperature. These were stored in 2-8°C refrigerators and tested once weekly for 6 months on multiple platforms with different detection principles: Rapid tests, second-generation enzyme-linked immunosorbent assay (ELISA), fourth-generation ELISA, and fourth-generation Chemiluminescence immunoassay. The protocol was sustained over the next 6 months with decreased testing frequency to study the extended stability of DTS.

RESULTS

A total of 139 positive-DTS and 139 negative-DTS were tested with 100% samples showing consistent results on all platforms over 1 year. There was mild deterioration in reaction strengths, which did not interfere in result interpretations.

CONCLUSION

Plasma in form of DTS maintained stability when stored at 2-8°C for 1 year. This provides evidence that DTS can be a modality for the production of cost-effective, stable, in-house control material for resource-restricted countries.

Repository of intra- and inter-run variations of quantitative autoantibody assays: a European multicenter study

OBJECTIVES

No reference data are available on repositories to measure precision of autoantibody assays. The scope of this study was to document inter- and intra-run variations of quantitative autoantibody assays based on a real-world large international data set.

METHODS

Members of the European Autoimmunity Standardisation Initiative (EASI) group collected the data of intra- and inter-run variability obtained with assays quantifying 15 different autoantibodies in voluntary participating laboratories from their country. We analyzed the impact on the assay performances of the type of immunoassay, the number of measurements used to calculate the coefficient of variation (CVs), the nature and the autoantibody level of the internal quality control (IQC).

RESULTS

Data were obtained from 64 laboratories from 15 European countries between February and October 2021. We analyzed 686 and 1,331 values of intra- and inter-run CVs, respectively. Both CVs were significantly dependent on: the method of immunoassay, the level of IQC with higher imprecision observed when the antibody levels were lower than 2-fold the threshold for positivity, and the nature of the IQC with commercial IQCs having lower CVs than patients-derived IQCs. Our analyses also show that the type of autoantibody has low impact on the assay' performances and that 15 measurements are sufficient to establish reliable intra- and inter-run variations.

CONCLUSIONS

This study provides for the first time an international repository yielding values of intra- and inter-run variation for quantitative autoantibody assays. These data could be useful for ISO 15189 accreditation requirements and will allow clinical diagnostic laboratories to assure quality of patient results.

Analysis of current status of quantitative detection of biomarkers for liver fibrosis in Clinical labs in China

Aim

To explore the quality control and implementation of the quantitative detection of liver fibrosis biomarkers, laminin (LN), collagen IV (Col Ⅳ), procollagen III amino‐terminal propeptide (PⅢNP), hyaluronic acid (HA), and cholyglycine (CG), in China.

Methods

Two quality control products were measured in different laboratories using different measurement methods and reagents, and the acquired results were subjected to analysis. The quantitative detection technique was based on the conventional assessment criteria, with a target value ±30% being employed.

Results

Hundred labs were involved in the External Quality Assessment with 88 laboratories completing the assessment, and the pass rates were 84%, 80.2%, 67.5%, 77.3%, and 58.3% for HA, LN, PⅢNP, Col Ⅳ, and CG, respectively. Chemiluminescence immunoassay was used most for HA (90.1%), LN (90.1%), PⅢNP (87.9%), and Col Ⅳ (82.9%) determination, whereas the chemiluminescence immunoassay (31.6%), latex‐enhanced immunoturbidimetry (36.7%), and homogeneous enzyme immunoassay (26.7%) were used for CG determination. The coefficients of variation for HA, LN, PⅢNP, Col Ⅳ, and CG in different laboratories were 3.3%–19.49%, 1.74%–38.81%, 1.97%–41.29%, 2.85%–41.69%, and 2.71%–41.8%, respectively.

Conclusion

The clinical quantitative detection of liver fibrosis biomarkers is highly performed in China. The existing problems are that there are many manufacturers producing reagents and instruments, the quality of reagents is uneven, the specificity and sensitivity of reagents are greatly different, the comparability of results of various systems is poor, and the accuracy and consistency between different systems are lacking. All above underscores the critical importance of EQA in improving and monitoring the identification of biomarkers for liver fibrosis.

How to Really Understand and Improve the System of Internal Quality Control and External Quality Assessment in the Accreditation Process of the Medical Laboratory?

Internal quality control (IQC) regarding process to monitor analytical stability has a long tradition in laboratory medicine. The satisfactory results with different quality specifications of the IQC ensure the acceptability of the examination results. Although the statistical IQC is satisfactory some problems exist, resulting in unreliable patients' results due several reasons (non-commutable control materials, lot to lot difference of reagents, false interpreting test results regarding autovalidation or autoverification, different analytical and clinical specifications or goals etc.). Therefore, the results and findings of IQC have to be connected with external quality assessment (EQA) in order to provide the system of measurement of uncertainty (MU) with correct interpretation of laboratory result and detection relevant and significant shifts and drifts in medical laboratory.

A study of the moving rate of positive results for use in a patient-based real-time quality control program on a procalcitonin point-of-care testing analyzer

Objective

To establish an applicable and highly sensitive patient‐based real‐time quality control (PBRTQC) program based on a data model constructed with patients’ results of a procalcitonin point‐of‐care testing (POCT) analyzer.

Methods

Patients’ results were retrospectively collected within one year. The Excel software was used to establish quality control (QC) programs of the moving average (MA) and the moving rate of positive results (MR). A Monte Carlo simulation was used to introduce positive and negative biases between 0.01 and 1 ng/ml at random points of the testing data set. Different parameters were used to detect the biases, and the detection efficiency was expressed using the median number of patient samples affected until error detection (MNPed). After comparing the MNPeds of different programs, MA and MR programs with appropriate parameters were selected, and validation plots were generated using MNPeds and maximum number of the patient samples affected (MAX). β curves were generated using the power function of the programs, the performances were compared with that of the conventional QC program.

Results

Neither the conventional QC nor MA program was sensitive to small bias, While MR program can detect the minimum positive bias of 0.06 ng/ml and negative of 0.4 ng/ml at an average daily run size of 10 specimens, with FRs < 1.0%, βs < 1%.

Conclusion

The MR program, which is more sensitive to small biases than conventional QC and MA programs, with low FR and β. As such, it can be used as a PBRTQC program with high performance.

Investigation of the quantitative detection of serum Helicobacter pylori antibody in clinical laboratories in China

Background

This study aimed to investigate the implementation and quality control of the quantitative detection of serum Helicobacter pylori (H. pylori) antibody in clinical laboratories in China.

Methods

Online external quality assessment (EQA) questionnaires were distributed to the clinical laboratories by National Center for Clinical Laboratories (NCCL) of China. We collected information on the quantitative detection procedures of serum H. pylori antibody in clinical laboratories, including detection reagents, methods, instruments, calibrators, and internal quality control (IQC). We distributed quality control products to some select laboratories that conducted quantitative detection and analyzed the obtained test data. We evaluated the quantitative detection procedure based on the standard evaluation criteria set at a target value of ±30%.

Results

70.9% (146/206) of the laboratories conducted quantitative detection of H. pylori antibody; 29.1% (60/206) of the laboratories performed qualitative detection. Domestic reagents and matching calibrators accounted for more than 97.1% (200/206) of all reagents. Latex‐enhanced immunoturbidimetry was used in 89.7% (131/146) of the laboratories for quantitative determination, while the colloidal gold method was used in 66.7% (40/60) of the laboratories for qualitative determination. A total of 130 laboratories participated in the EQA; 123 completed the assessment, and the pass rate was 75.6% (93/123).

Conclusion

Clinical quantitative detection of serum H. pylori antibody is performed at a high rate in China. Thus, further studies on the specificity of commercial detection reagents are needed. EQAs are useful to monitor and improve the detection quality of H. pylori antibodies.

Influence of reagent lots and multiple measuring systems on estimating the coefficient of variation from quality control data; implications for uncertainty estimation and interpretation of QC results

Background Clinical laboratories use internal quality control (QC) data to calculate standard deviation (SD) and coefficient of variation (CV) to estimate uncertainty of results and to interpret QC results. We examined the influence of different instruments, and QC and reagent lots on the CV calculated from QC data. Methods Results for BioRad Multiqual frozen liquid QC samples over a 2-year interval were partitioned by QC and reagent lots. The mean and CV were calculated for each partition for each of three Abbott Architect c8000 instruments for measuring serum alanine amino transferase (ALT), creatinine (enzymatic), glucose and sodium. Results CVs differed among partitions and instruments for two QC levels by 5.8- and 3.3-fold for ALT, by 4.7- and 2.1-fold for creatinine, by 2.0- and 2.6-fold for glucose, and by 2.1- and 2.0-fold for sodium. Pooled CVs for two QC levels varied among instruments by 1.78- and 1.11-fold for ALT, by 1.63- and 1.11-fold for creatinine, by 1.08- and 1.06-fold for glucose, and by 1.24- and 1.31-fold for sodium. Conclusions The CVs from QC data varied substantially among QC and reagent lots and for different identical specification instruments. The CV used to estimate uncertainty for a measurement result or as the basis for interpreting individual QC results must be derived over a sufficient time interval to obtain a pooled CV that represents "typical" performance of a measuring system. An estimate of uncertainty provided to users of laboratory results will itself have uncertainty that can influence medical decisions.

Implementation of internal quality control program for monitoring of enzyme-linked immunosorbent assay performance at a blood center

BACKGROUND:

Internal quality control (IQC) samples may be incorporated in enzyme-linked immunosorbent assay (ELISA) routinely for detection of errors occurring due to change in environmental conditions, test system, or operator performance. We have described methodology for preparation of IQC samples, monitoring of results using Levey–Jennings (LJ) charts and their interpretation. We have also described our experience of quality control in ELISA using IQC samples, identification of errors and corrections applied.

MATERIALS AND METHODS:

IQC samples for anti-HIV, hepatitis B surface antigen (HBsAg), and anti-HCV ELISA were prepared “in-house” using standard methodology. After validation of run, E-ratio of IQC sample was calculated and plotted on LJ chart. Further interpretation was done to detect the errors. LJ charts illustrating the performance of IQC samples on 180 runs for each ELISA were drawn and analyzed.

RESULTS:

For anti-HIV ELISA, violation of warning rule was found in 2 runs (1.11%). Only one run (0.55%) was rejected due to violation of rejection rule. For HBsAg ELISA, violation of warning rule was indicated in two runs (1.11%). Two runs (1.11%) were rejected due to violation of rejection rules. For anti-HCV ELISA, violation of warning rule was indicated in two runs (1.11%), whereas two runs were rejected due to violation of rejection rules. Comprehensive checks were performed for the evaluation of equipment calibration, handling, and storage temperature of reagents and operator's technique. A thorough investigation was undertaken according to the type of error.

CONCLUSION:

Inclusion of IQC with each ELISA run is valuable to check the assay performance, ensuring reliability and reproducibility of test results.

Sigma Metric Evaluation of Drugs in a Clinical Laboratory: Importance of Choosing Appropriate Total Allowable Error and a Troubleshooting Roadmap

Objectives  Stringent quality control is an essential requisite of diagnostic laboratories to deliver consistent results. Measures used to assess the performance of a clinical chemistry laboratory are internal quality control and external quality assurance scheme (EQAS). However, the number of errors cannot be measured by the above but can be quantified by sigma metrics. The sigma scale varies from 0 to 6 with “6” being the ideal goal, which is calculated by using total allowable error (TEa), bias, and precision. However, there is no proper consensus for setting a TEa goal, and influence of this limiting factor during routine laboratory practice and sigma calculation has not been adequately determined. The study evaluates the impact of the choice of TEa value on sigma score derivation and also describes a detailed structured approach (followed by the study laboratory) to determine the potential causes of errors causing poor sigma score.

Materials and Methods  The study was conducted at a clinical biochemistry laboratory of a central government tertiary care hospital. Internal and external quality control data were evaluated for a period of 5 months from October 2019 to February 2020. Three drugs (carbamazepine, phenytoin, and valproate) were evaluated on the sigma scale using two different TEa values to determine significant difference, if any.

Statistical Analysis  Bias was calculated using the following formula: Bias% = (laboratory EQAS result − peer group mean) × 100 / peer group mean Peer group mean sigma metric was calculated using the standard equation: Sigma value = TEa − bias / coefficient of variation (CV)%.

Results  Impressive sigma scores (> 3 sigma) for two out of three drugs were obtained with TEa value 25, while with TEa value 15, sigma score was distinctly dissimilar and warranted root cause analysis and corrective action plans to be implemented for both valproate and carbamazepine.

Conclusions  The current study evidently recognizes that distinctly different sigma values can be obtained, depending on the TEa values selected, and using the same bias and precision values in the sigma equation. The laboratories should thereby choose appropriate TEa goals and make judicious use of sigma metric as a quality improvement tool.

Recommendations for the application and follow-up of quality controls in medical laboratories

This is a translation of the paper “Recommendations for the application and follow-up of quality controls in medical biology laboratories” published in French in the journal Annales de Biologie Clinique (Recommandations pour la mise en place et le suivi des contrôles de qualité dans les laboratoires de biologie médicale. Ann Biol Clin (Paris). 2019;77:577-97.). The recommendations proposed in this document are the result of work conducted jointly by the Network of Accredited Medical Laboratories (LABAC), the French Society of Medical Biology (SFBC) and the Federation of Associations for External Quality Assessment (FAEEQ). The different steps of the implementation of quality controls, based on a risk analysis, are described. The changes of reagent or internal quality control (IQC) materials batches, the action to be taken in case of non-conform IQC results, the choice of external quality assessment (EQA) scheme and interpretation of their results as well as the new issue of analyses performed on several automatic systems available in the same laboratory are discussed. Finally, the concept of measurement uncertainty, the robustness of the methods as well as the specificities of near-patient testing and rapid tests are described. These recommendations cannot apply for all cases we can find in medical laboratories. The implementation of an objective alternative strategy, supported with documented evidence, might be equally considered.

Applying the concept of uncertainty to the sFlt-1/PlGF cut-offs for diagnosis and prognosis of preeclampsia

OBJECTIVES

Placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) assays and the corresponding ratios (sFlt-1/PlGF) have been proposed to aid in the diagnosis by exclusion and/or prognosis of preeclampsia (PE). A method for evaluating ratio uncertainties (RUs), based on the theory of error propagation, was applied to the sFlt-1/PlGF ratio.

METHODS

RUs were calculated using data derived from sFlt-1 and PlGF Internal Quality Control (IQC) results collected from four centers using Elecsys (Roche) or Kryptor (Thermo Fisher) sFlt-1 and PlGF assays. The corresponding ratio uncertainties were defined for each ratio value.

RESULTS

The RUs increased linearly with the sFlt-1/PlGF ratio values. The Elecsys RUs were lower than the Kryptor RUs. Although RUs cannot eliminate differences in ratio values observed among various immunoassays, it can affect interpretation of the sFlt-1/PlGF ratio, especially when results are within the range of predefined PE diagnosis or prognosis cut-offs.

CONCLUSIONS

Since RUs are only a function of PlGF and sFlt-1 precision, they can be calculated for each assay from each laboratory to adjust the interpretation of sFlt-1/PlGF ratio results in the context of PE.

Efficacy of Pooled Serum Internal Quality Control in Comparison with Commercial Internal Quality Control in Clinical Biochemistry Laboratory

Introduction  With increasing automation in clinical laboratories, the requirements for quality control (QC) material have greatly increased in order to monitor performance. The constant use of commercial control material is not economically feasible for many countries because of nonavailability or the high-cost of those materials. Therefore, preparation and use of in-house QC serum will be a very cost-effective measure with respect to laboratory needs. Materials and Methods  In-house internal quality control from leftover serum samples of master health checkup subjects, which have been screened negative for HIV, HCV and HBsAg antibodies was pooled in a glass jar with ethanediol as preservative and kept in deep freezer at - 20°C. From the pooled serum, 100 microliter thirty aliquots were prepared. Every day along with commercial internal QC (IQC), one aliquot of pooled serum was analyzed for 30 days for the following parameters: plasma glucose, blood urea, serum creatinine, total cholesterol, triglycerides (TGL), high-density lipoprotein, calcium, total protein, albumin, total bilirubin, AST, ALT, ALP, amylase. After getting 30 values for each parameter, mean, standard deviation (SD) and CV% were calculated for both IQC commercial sample and pooled serum sample. Results  The mean, SD, and CV% of glucose, cholesterol, TGL, calcium, alanine aminotransaminase (ALT), aspartate aminotransferase (AST), amylase, and alkaline phosphatase (ALP) were statistically significant between pooled serum and commercial QC. Conclusion  In-house QC prepared from pooled serum is better than commercial internal QC. The biochemical parameters were stable in pooled serum due to less matrix effect; also, variation was less in pooled serum IQC.

Evaluation of the analytical performance of endocrine analytes using sigma metrics

Background

(a) To evaluate the clinical performance of endocrine analytes using the sigma metrics (σ) model. (b) To redesign quality control strategies for performance improvement.

Methods

The sigma values of the analytes were initially evaluated based on the allowable total error (TEa), bias, and coefficient of variation (CV) at QC materials level 1 and 2 in March 2018. And then, the normalized QC performance decision charts, personalized QC rules, quality goal index (QGI) analysis, and root causes analysis (RCA) were performed based on the sigma values of the analytes. Finally, the sigma values were re‐evaluated in September 2018 after a series of targeted corrective actions.

Results

Based on the initial sigma values, two analytes (FT3 and TSH) with σ > 6, only needed one QC rule (1_3S) with N2 and R500 for QC management. On the other hand, seven analytes (FT4, TT4, CROT, E2, PRL, TESTO, and INS) with σ < 4 at one QC material level or both needed multiple rules (1_3S/2_2S/R_4S/4_1S/10_X) with N6 and R10‐500 depending on different sigma values for QC management. Subsequently, detailed and comprehensive RCA and timely corrective actions were performed on all the analytes base on the QGI analysis. Compared with the initial sigma values, the re‐evaluated sigma metrics of all the analytes increased significantly.

Conclusions

It was demonstrated that the combination of sigma metrics, QGI analysis, and RCA provided a useful evaluation system for the analytical performance of endocrine analytes.

[Recommendations for the application and the follow-up of quality controls in medical biology laboratories]

The recommendations that we formulate in this document come from LABAC, SFBC and FAEEQ. They describe the different steps from the initial application of quality controls, based on risk analysis: the changes of reagent batches or internal quality controls (IQC) batches, the course when IQC are not in accordance with references, the choice of external quality evaluation and the interpretation of its results, the comparability of results obtained in several analysers used in the same laboratory. Lastly, measurement uncertainty, robustness of methods and specificities of near-patient biology and rapid tests are described. Note that these recommendations cannot develop all cases that we could find in laboratories. It remains necessary to carry out an objective strategy, supported with documentary evidences.

Sigma metrics as a tool for evaluating the performance of internal quality control in a clinical chemistry laboratory

OBJECTIVE:

Six Sigma is one of the most popular quality management system tools employed for process improvement. The Six Sigma methods are usually applied when the outcome of the process can be measured. This study was done to assess the performance of individual biochemical parameters on a Sigma Scale by calculating the sigma metrics for individual parameters and to follow the Westgard guidelines for appropriate Westgard rules and levels of internal quality control (IQC) that needs to be processed to improve target analyte performance based on the sigma metrics.

MATERIALS AND METHODS:

This is a retrospective study, and data required for the study were extracted between July 2015 and June 2016 from a Secondary Care Government Hospital, Chennai. The data obtained for the study are IQC - coefficient of variation percentage and External Quality Assurance Scheme (EQAS) - Bias% for 16 biochemical parameters.

RESULTS:

For the level 1 IQC, four analytes (alkaline phosphatase, magnesium, triglyceride, and high-density lipoprotein-cholesterol) showed an ideal performance of ≥6 sigma level, five analytes (urea, total bilirubin, albumin, cholesterol, and potassium) showed an average performance of <3 sigma level and for level 2 IQCs, same four analytes of level 1 showed a performance of ≥6 sigma level, and four analytes (urea, albumin, cholesterol, and potassium) showed an average performance of <3 sigma level. For all analytes <6 sigma level, the quality goal index (QGI) was <0.8 indicating the area requiring improvement to be imprecision except cholesterol whose QGI >1.2 indicated inaccuracy.

CONCLUSION:

This study shows that sigma metrics is a good quality tool to assess the analytical performance of a clinical chemistry laboratory. Thus, sigma metric analysis provides a benchmark for the laboratory to design a protocol for IQC, address poor assay performance, and assess the efficiency of existing laboratory processes.

[Uncertainty Evaluation and Internal Quality Control of ELISA Test for Food Allergens (in Egg and Milk) Using Control Samples]

We evaluated measurement uncertainty and performed internal quality control of an ELISA test for allergens in egg and milk, using control samples. For the evaluation of measurement uncertainty, the following three important factors were identified: 1) Differences in test-kit lots, 2) Different-day reproducibility, 3) Same-time reproducibility. A three-stage nested design was used, and the combined standard uncertainty of the three factors mentioned above was calculated based on the results obtained. Measurement uncertainty was defined as the expanded uncertainty obtained by multiplying the combined standard uncertainty by a coverage factor of two. As a result, the expanded uncertainty of egg was 1.9 μg/g when the total egg protein concentration was 13.4 μg/g, and the expanded uncertainty of milk was 1.8 μg/g when the total milk protein concentration was 13.5 μg/g. For the internal quality control, we first set the reference range of the measured value of the control sample, using the obtained combined standard uncertainty as an index. Each control sample was then measured for every test, and we concluded that the test was performed without any errors, when the result of the control sample was within the reference range. Second, the measured values of the control samples were plotted on a graph for continuous monitoring. This enabled us to check whether inspection accuracy was maintained. There were no large chronological changes and no major differences between the standard deviations of the control samples and the combined standard uncertainty in egg or milk. Therefore, it was determined that the dispersion was at an acceptable range and inspection accuracy was maintained.

Comparative analysis of calculating sigma metrics by a trueness verification proficiency testing-based approach and an internal quality control data inter-laboratory comparison-based approach

Introduction

Two methods were compared for evaluating the sigma metrics of clinical biochemistry tests using two different allowable total error (TEa) specifications.

Materials and methods

The imprecision (CV%) and bias (bias%) of 19 clinical biochemistry analytes were calculated using a trueness verification proficiency testing (TPT)‐based approach and an internal quality control data inter‐laboratory comparison (IQC)‐based approach, respectively. Two sources of total allowable error (TEa), the Clinical Laboratory Improvement Amendments of 1988 (CLIA '88) and the People's Republic of China Health Industry Standard (WS/T 403‐2012), were used to calculate the sigma metrics (σ_CLIA, σ_WS/T). Sigma metrics were calculated to provide a single value for assessing the quality of each test based on a single concentration level.

Results

For both approaches, σ_CLIA > σ_WS/T in 18 out of 19 assays. For the TPT‐based approach, 16 assays showed σ_CLIA > 3, and 12 assays showed σ_WS/T > 3. For the IQC‐based approach, 19 and 16 assays showed σ_CLIA > 3 and σ_WS/T > 3, respectively.

Conclusions

Both methods can be used as references for calculating sigma metrics and designing QC schedules in clinical laboratories. Sigma metrics should be evaluated comprehensively by different approaches.

Sigma metrics for assessing the analytical quality of clinical chemistry assays: a comparison of two approaches: Electronic supplementary material available online for this article

Introduction

Two approaches were compared for the calculation of coefficient of variation (CV) and bias, and their effect on sigma calculation, when different allowable total error (TEa) values were used to determine the optimal method for Six Sigma quality management in the clinical laboratory.

Materials and methods

Sigma metrics for routine clinical chemistry tests using three systems (Beckman AU5800, Roche C8000, Siemens Dimension) were determined in June 2017 in the laboratory of Peking Union Medical College Hospital. Imprecision (CV%) and bias (bias%) were calculated for ten routine clinical chemistry tests using a proficiency testing (PT)- or an internal quality control (IQC)-based approach. Allowable total error from the Clinical Laboratory Improvement Amendments of 1988 and the Chinese Ministry of Health Clinical Laboratory Center Industry Standard (WS/T403-2012) were used with the formula: Sigma = (TEa - bias) / CV to calculate the Sigma metrics (σ_CLIA, σ_WS/T) for each assay for comparative analysis.

Results

For the PT-based approach, eight assays on the Beckman AU5800 system, seven assays on the Roche C8000 system and six assays on the Siemens Dimension system showed σ_CLIA > 3. For the IQC-based approach, ten, nine and seven assays, respectively, showed σ_CLIA > 3. Some differences in σ were therefore observed between the two calculation methods and the different TEa values.

Conclusions

Both methods of calculating σ can be used for Six Sigma quality management. In practice, laboratories should evaluate Sigma multiple times when optimizing a quality control schedule.

Implementing Dynamic Headspace With SPME Sampling of Virgin Olive Oil Volatiles: Optimization, Quality Analytical Study, and Performance Testing

Competition and interaction phenomena among volatiles during their adsorption process by solid phase microextraction (SPME) fibers in static headspace sampling procedure (SHS) cast doubt on its ability to quantify virgin olive oil volatiles. SPME fibers being excellent traps, their use was analyzed with a new device allowing the concentration of volatiles in a dynamic headspace sampling procedure (DHS). A central composite experimental design optimized the main variables of the device (4 g sample weight, 40 °C temperature, 150 mL/min flow rate, 50 min adsorption time), while values of the analytical quality control parameters of the method (repeatability, limits of detection and quantification, working range, sensitivity, and resolution) were compared with those ones from static headspace. DHS shows better precision results for aldehydes and alcohols than SHS and allowed analyzing higher concentrations with no problem of saturation. In 19 of 28 compounds analyzed in 50 samples the chromatographic areas were higher when running DHS. The concentration values of volatile compounds in these samples after applying SHS and DHS are discussed together with the ability of the new method for distinguishing virgin olive oil by their categories (extra virgin, virgin, and lampante) by the volatiles quantified in commercial oils.

Internal quality control status for BNP and NT-proBNP in China from 2014 to 2017

BACKGROUND

This study aimed to investigate and analyze the status of internal quality control (IQC) for BNP and NT-proBNP from 2014 to 2017, so as to have an integral understanding of quality performance of measurement in clinical laboratories in China.

METHODS

The 4-year IQC information for BNP and NT-proBNP of participant laboratories were collected through EQA reporting system. Percentages of laboratories meeting different quality requirements (pass rates) for current coefficient of variations (CVs) were calculated afterwards. Further analysis for current CVs and pass rates among different years and measurement systems were conducted. Finally, we analyzed and summarized IQC practice and its changes in 4 years.

RESULTS

The current CVs for BNP and NT-proBNP have decreased significantly from 2014 to 2017, and pass rates both presented significant increasing trends. NT-proBNP had higher pass rates than BNP regardless of 1/3TEa or 1/4TEa specification was used. The main measurement systems for two analytes were different. For NT-proBNP, current CVs of Roche has decreased significantly among 4 years and were significantly lower than Radiometer and BioMérieux in 2015. Current CVs of Abbott also had decreasing tendency for BNP. Analysis of IQC practice indicated that control rules and IQC frequency had made great progress in 4 years.

CONCLUSION

The imprecision performance of measurement of BNP and NT-proBNP has improved with decreasing of current CVs and increasing of pass rates in 4 years. However, it still needs continual improvement. Clinical laboratories in China should take active actions to promote performance of BNP and NT-proBNP measurement.

Comparison of two commercial quality control sera for adrenocorticotropin (ACTH) used in Elecsys® immunoassay system

OBJECTIVES

The purpose of our study was to investigate whether the storage time and temperature of internal quality control (IQC) material influence the result of ACTH in IQC measurements.

DESIGN AND METHODS

Five levels of IQC materials from two manufacturers were tested through the precision of ACTH, the three freeze/thaw cycles, and the storage time and temperature to evaluate the stability of IQC material. All commercial control materials were simultaneously tested three times a day for five consecutive days.

RESULTS

Total precision of three levels of Bio-Rad IQC sera was 13.93%, 16.45%, and 15.98%, respectively, but repeatability was <2%. The concentration of ACTH decreased by 30%-50% after 3 freeze/thaw cycles. At room temperature, the concentration of ACTH from 3 levels decreased by 16.60%, 17.98%, and 17.20%, respectively, after 0.5 hours, and 70.54%, 74.36%, and 72.03%, respectively, after 4 hours. However, after 2 hours of storage at 4°C, the decline in the measured ACTH IQC was 8.04%, 11.84%, and 10.11%, respectively. Total precision of Roche IQC was 1.17% and 1.08%, respectively. After 3 freeze/thaw cycles, the concentration of ACTH decreased <5%. After 4 hours, the change of ACTH still steadied within 5% both at the room temperature and at 4°C.

CONCLUSION

Roche is a better choice for ACTH of IQC material in Elecsys^® immunoassay system in our study. If Bio-Rad control materials be used in Elecsys^® immunoassay system for ACTH IQC testing material, it should be stored at 4°C and testing should be completed within 1 hours.

National survey on internal quality control for tumour markers in clinical laboratories in China

Introduction

This survey was initiated to obtain knowledge on the current situation of internal quality control (IQC) practice for tumour markers (TMs) in China. Additionally, we tried to acquire the most appropriate quality specifications.

Materials and methods

This survey was a current status survey. The IQC information had been collected via online questionnaires. All of 1821 clinical laboratories which participated in the 2016 TMs external quality assessment (EQA) programme had been enrolled. The imprecision evaluation criteria were the minimal, desirable, and optimal allowable imprecisions based on biological variations, and 1/3 total allowable error (TEa) and 1/4 TEa.

Results

A total of 1628 laboratories answered the questionnaires (89%). The coefficients of variation (CVs) of the IQC of participant laboratories varied greatly from 1% (5^th percentile) to 13% (95^th percentile). More than 82% (82 - 91%) of participant laboratories two types of CVs met 1/3 TEa except for CA 19-9. The percentiles of current CVs were smaller than cumulative CVs. A number of 1240 laboratories (76%) reported their principles and systems used. The electrochemiluminescence was the most used principle (45%) and had the smallest CVs.

Conclusions

The performance of laboratories for TMs IQC has yet to be improved. On the basis of the obtained results, 1/3 TEa would be realistic and attainable quality specification for TMs IQC for clinical laboratories in China.

An update on quality control for the PFA-100/PFA-200

Testing of platelet function comprises a crucial element of hemostasis assessment, particularly for investigations into bleeding and/or bruising. The Platelet Function Analyzer (PFA)-100 is the most utilized primary hemostasis-screening test system available, as recently remodeled/upgraded to the PFA-200. Internal quality control (IQC) and external quality assessment (EQA) (including proficiency testing) represent critical elements of ensuring test practice quality. Although true for all tests, IQC and EQA are logistically challenging for platelet function testing, inclusive of the PFA-100/200. We accordingly update our experience with novel yet feasible approaches to both IQC and EQA of PFA-100/200. Over the past 10 years, a total of 43 challenges have been tested, with most challenges designed to mimic moderate or severe primary hemostasis defects. The current report is restricted to the last four years and has also differentially assessed PFA-100 vs. PFA-200 EQA results to identify potential variance. Numerical results for closure times (CTs) and participant-supplied interpretive comments were analyzed. Reported CTs for each challenge were within limits of expectation, and good reproducibility was evidenced by repeated challenges. Coefficients of variation (CVs) for challenges, generally ranging from 15% to 25%, were similar or better than those obtained using native whole blood and consistent with past reports. Participant interpretations were generally consistent with test data and expectations. There was no evident difference in PFA-100 vs. PFA-200 EQA test results. The EQA material has also been successfully evaluated from the perspective of potential IQC. To conclude, IQC and EQA processes for the PFA-100/200 have been established that are highly reproducible, supporting the concept of EQA/IQC for platelet function testing, and also facilitating monitoring and improvement in its performance. In terms of EQA, PFA-100 and PFA-200 instruments appear to behave similarly.

Internal quality control of blood products: An experience from a tertiary care hospital blood bank from Southern Pakistan

INTRODUCTION:

Internal quality control (IQC) is the backbone of quality assurance program. In blood banking, the quality control of blood products ensures the timely availability of a blood component of high quality with maximum efficacy and minimal risk to potential recipients. The main objective of this study is to analyze the IQC of blood products as an indicator of our blood bank performance.

METHODS:

An observational cross-sectional study was conducted at the blood bank of Liaquat National Hospital and Medical College, from January 2014 to December 2015. A total of 100 units of each blood components were arbitrarily chosen during the study. Packed red cell units were evaluated for hematocrit (HCT); random platelet concentrates were evaluated for pH, yield, and culture; fresh frozen plasma (FFP) and cryoprecipitate (CP) were evaluated for unit volume, factor VIII, and fibrinogen concentrations.

RESULTS:

A total of 400 units were tested for IQC. The mean HCT of packed red cells was 69.5 ± 7.24, and in 98% units, it met the standard (<80% of HCT). The mean platelet yield was 8.8 ± 3.40 × 10⁹/L and pH was ≥6.2 in 98% bags; cultures were negative in 97% of units tested. Mean factor VIII and fibrinogen levels were found to be 84.24 ± 15.01 and 247.17 ± 49.69 for FFP, respectively. For CP, mean factor VIII and fibrinogen level were found to be 178.75 ± 86.30 and 420.7 ± 75.32, respectively.

CONCLUSION:

The IQC of blood products at our blood bank is in overall compliance and met recommended international standards. Implementation of standard operating procedures, accomplishment of standard guidelines, proper documentation with regular audit, and staff competencies can improve the quality performance of the transfusion services.

[Validation Study of Analytical Method for Determination of Amnesic Shellfish Poison in Bivalves]

Amnesic shellfish poison (ASP) is regarded as one of the shellfish poison groups in the EU, though it is not subject to regulation in Japan. We have developed an analytical method of ASP based on the report by Hatfield et al. and other methods. Validation studies were carried out with certified compositional reference materials (CRM). Performance parameters were estimated based on 17 analytical results. The estimate of trueness was 97.5%, and the estimate of intralaboratory reproducibility (RSD) was 1.5%. The HorRat(r) value was 0.16. These performance parameters meet the criteria in the Codex Procedural Manual. Furthermore, internal quality control was performed by using the CRM. The action limits were set based on the performance parameters of the method. Most of the results of the internal quality control were within the action limit range. The results confirmed that the quality of the analyses was well maintained. The purpose of the analytical method is to confirm that the level of ASP in scallop is less than 4.6 mg/kg. The applicability of the analytical method to scallops was confirmed by using spiked samples.

IQC Laboratory management strategy for medical biology

Medical biology laboratories rely especially on internal quality control (IQC) to monitor the performance of equipment and ensure results reliability. Strategies for these controls vary considerably from one laboratory to another. Some laboratories use Westgard's rules to detect drifts and are faced with a large number of false rejections caused by frequent runs of control samples and strategies that activate all rejection rules, regardless of the analyte considered. To minimize these rejections, some laboratories have combined several theories, sometimes despite the relevance of the resulting strategy. In this article, we want to explain the foundations of the main IQC theories and set out a strategy to optimize the detection of problems while minimizing false IQC rejections. We will also address some frequently asked questions from laboratories as part of ISO 15189 accreditation.

Implementation of buffy-coat-derived pooled platelet concentrates for internal quality control of light transmission aggregometry: a proof of concept study

Essentials In platelet function testing, standardized internal controls (IQC) are not commercially provided. Platelet function testing was performed daily on aliquoted pooled platelet concentrates. Pooled platelet concentrates showed stability for control purposes from Monday to Friday. Pooled platelet concentrates provide the necessary steadiness to serve as IQC material.

SUMMARY

Background Standardized commercially available control material for internal quality control (IQC) of light transmission aggregometry (LTA) is still lacking. Moreover, the availability of normal blood donors to provide fresh platelets is difficult in small laboratories, where 'volunteers' may be in short supply. Objectives To evaluate the implementation of buffy-coat-derived pooled platelet concentrates (PCs) for IQC material for LTA. Methods We used buffy-coat-derived pooled PCs from the blood bank as IQC material for LTA. On each weekend one PC was prepared (> 200 mL) and aliquoted from the original storage bag on a daily basis in four baby bags (40-50 mL), which were delivered from Monday to Friday to our laboratory. The IQC measurements of at least 85 work-weeks (from Monday to Friday) were evaluated with this new IQC material. LTA was performed on a four-channel Chronolog 700 Aggregometer (Chronolog Corporation, Havertown, PA, USA) (agonists: collagen, adenosine diphosphate [ADP], arachidonic acid [AA] and thrombin receptor activator peptide-6 [TRAP-6]). Results The medians of platelet aggregation from IQC measurements with collagen, ADP and AA from Monday to Friday were 68.0-59.5, 3.0-2.0 and 51.0-50.0%, respectively, and the mean of platelet aggregation with TRAP-6 was 71.2-66.4%. Conclusions Buffy-coat-derived pooled PCs serve as a reliable and robust IQC material for LTA measurements and would be beneficial for the whole laboratory procedure and employees' safety.

National continuous surveys on internal quality control for HbA1c in 306 clinical laboratories of China from 2012 to 2016: Continual improvement

BACKGROUND

This study aimed to evaluate whether the quality performance of clinical laboratories in China has been greatly improved and whether Internal Quality Control (IQC) practice of HbA1c has also been changed since National Center for Clinical Laboratories (NCCL) of China organized laboratories to report IQC data for HbA1c in 2012.

METHODS

Internal Quality Control information of 306 External Quality Assessment (EQA) participant laboratories which kept reporting IQC data in February from 2012 to 2016 were collected by Web-based EQA system. Then percentages of laboratories meeting four different imprecision specifications for current coefficient of variations (CVs) of HbA1c measurements were calculated. Finally, we comprehensively analyzed analytical systems and IQC practice of HbA1c measurements.

RESULTS

The current CVs of HbA1c tests have decreased significantly from 2012 to 2016. And percentages of laboratories meeting four imprecision specifications for CVs all showed the increasing tendency year by year. As for analytical system, 52.1% (159/306) laboratories changed their systems with the change in principle of assay. And many laboratories began to use cation exchange high-performance liquid chromatography (CE-HPLC) instead of Immunoturbidimetry, because CE-HPLC owed a lower intra-laboratory CVs. The data of IQC practice, such as IQC rules and frequency, also showed significant variability among years with overall tendency of meeting requirements.

CONCLUSION

The imprecision performance of HbA1c tests has been improved in these 5 years with the change in IQC practice, but it is still disappointing in China. Therefore, laboratories should actively find existing problems and take action to promote performance of HbA1c measurements.

Key performance indicators score (KPIs-score) based on clinical and laboratorial parameters can establish benchmarks for internal quality control in an ART program

Objective

KPIs have been employed for internal quality control (IQC) in ART. However, clinical KPIs (C-KPIs) such as age, AMH and number of oocytes collected are never added to laboratory KPIs (L-KPIs), such as fertilization rate and morphological quality of the embryos for analysis, even though the final endpoint is the evaluation of clinical pregnancy rates. This paper analyzed if a KPIs-score strategy with clinical and laboratorial parameters could be used to establish benchmarks for IQC in ART cycles.

Methods

In this prospective cohort study, 280 patients (36.4±4.3years) underwent ART. The total KPIs-score was obtained by the analysis of age, AMH (AMH Gen II ELISA/pre-mixing modified, Beckman Coulter Inc.), number of metaphase-II oocytes, fertilization rates and morphological quality of the embryonic lot.

Results

The total KPIs-score (C-KPIs+L-KPIs) was correlated with the presence or absence of clinical pregnancy. The relationship between the C-KPIs and L-KPIs scores was analyzed to establish quality standards, to increase the performance of clinical and laboratorial processes in ART. The logistic regression model (LRM), with respect to pregnancy and total KPIs-score (280 patients/102 clinical pregnancies), yielded an odds ratio of 1.24 (95%CI = 1.16-1.32). There was also a significant difference (p<0.0001) with respect to the total KPIs-score mean value between the group of patients with clinical pregnancies (total KPIs-score=20.4±3.7) and the group without clinical pregnancies (total KPIs-score=15.9±5). Clinical pregnancy probabilities (CPP) can be obtained using the LRM (prediction key) with the total KPIs-score as a predictor variable. The mean C-KPIs and L-KPIs scores obtained in the pregnancy group were 11.9±2.9 and 8.5±1.7, respectively. Routinely, in all cases where the C-KPIs score was ≥9, after the procedure, the L-KPIs score obtained was ≤6, a revision of the laboratory procedure was performed to assess quality standards.

Conclusion

This total KPIs-score could set up benchmarks for clinical pregnancy. Moreover, IQC can use C-KPIs and L-KPIs scores to detect problems in the clinical-laboratorial interface.

Interest and limits of the six sigma methodology in medical laboratory

The mandatory accreditation of clinical laboratories in France provides an incentive to develop real tools to measure performance management methods and to optimize the management of internal quality controls. Six sigma methodology is an approach commonly applied to software quality management and discussed in numerous publications. This paper discusses the primary factors that influence the sigma index (the choice of the total allowable error, the approach used to address bias) and compares the performance of different analyzers on the basis of the sigma index. Six sigma strategy can be applied to the policy management of internal quality control in a laboratory and demonstrates through a comparison of four analyzers that there is no single superior analyzer in clinical chemistry. Similar sigma results are obtained using approaches toward bias based on the EQAS or the IQC. The main difficulty in using the six sigma methodology lies in the absence of official guidelines for the definition of the total error acceptable. Despite this drawback, our comparison study suggests that difficulties with defined analytes do not vary with the analyzer used.

Status of internal quality control for thyroid hormones immunoassays from 2011 to 2016 in China

BACKGROUND

Internal quality control (IQC) plays a key role in the evaluation of precision performance in clinical laboratories. This report aims to present precision status of thyroid hormones immunoassays from 2011 to 2016 in China.

METHODS

Through Clinet-EQA reporting system, IQC information of Triiodothyronine and Thyroxine in the form of free and total (FT3, TT3, FT4, TT4), as well as Thyroid Stimulating Hormone (TSH) were collected from participant laboratories submitting IQC data in February, 2011-2016. For each analyte, current CVs were compared among different years and measurement systems. Percentages of laboratories meeting five allowable imprecision specifications (pass rates) were also calculated. Analysis of IQC practice was conducted to constitute a complete report.

RESULTS

Current CVs were decreasing significantly but pass rates increasing only for FT3 during 6 years. FT3, TT3, FT4, and TT4 had the highest pass rates comparing with 1/3TEa imprecision specification but TSH had this comparing with minimum imprecision specification derived from biological variation. Constituent ratios of four mainstream measurement systems changed insignificantly. In 2016, precision performance of Abbott and Roche systems were better than Beckman and Siemens systems for all analytes except FT3 had Siemens also better than Beckman. Analysis of IQC practice demonstrated wide variation and great progress in aspects of IQC rules and control frequency.

CONCLUSION

With change of IQC practice, only FT3 had precision performance improved in 6 years. However, precision status of five analytes in China was still unsatisfying. Ongoing investigation and improvement of IQC have yet to be achieved.

[The establishment and application of internal quality control system for real-time quantitative PCR detection of BCR-ABL (P210) transcript levels]

Objective: To set internal quality control system of BCR-ABL (P210) transcript levels for real-time quantitative PCR (RQ-PCR). Methods: Using K562 cells and HL-60 cells, we prepared high- and low-level BCR-ABL internal quality control substance. The BCR-ABL (P210) transcript levels of internal quality control substance have been determined for 184 times together with clinical samples from August 2013 to October 2015. The slope rate, intercept and correlation coefficient of standard curve were calculated according to different reagent lots (lots number 20130303, 20131212, 20140411 and 20150327 are called R1、R2、R3 and R4 for short respectively), and the detection results of quality control substance were calculated according to different reagent lots and quality control substance lots (lots number 20130725, 20140611 are called Q1、Q2 for short respectively). Then the results were analyzed by Levey-Jennings quality control chart combined with Westgard multi-rules theory. Results: ①We analyzed the slope rate and intercept of standard curve. Fifty-three times of the R1 reagent detection, 80 times of the R3 reagent detection and 14 times of the R4 reagent detection were all under control. For 37 times detection of R2 reagent, the slope rate was out of control for 6 times. It was lower than x-s for the 2-8 tests and upper the average for the 12-37 tests. The intercept was out of control for 9 times, upper the x+s for the 1-8 tests and lower the average for the 12-37 tests. ② According to the detection results of quality control substance, for Q1 quality control substance, 49 tests by R1 reagent were under control, and 1 out of 23 tests by R2 reagent was out of control. For Q2 quality control substance, 14 tests by R2 reagent detection, 72 tests by R3 reagent detection and 14 tests by R4 reagent were all under control. Conclusion: The preparation of high- and low-level quality control substance using K562 and HL-60 cells was convenient and the detection results were reliable and stable. The application of quality control substance combined with slope rate and intercept in the internal quality control may contribute to quality assurance for quantitative detection of BCR-ABL (P210) transcript levels.

Contribution of Sample Processing to Variability and Accuracy of the Results of Pesticide Residue Analysis in Plant Commodities

Significant reduction of concentration of some pesticide residues and substantial increase of the uncertainty of the results derived from the homogenization of sample materials have been reported in scientific papers long ago. Nevertheless, performance of methods is frequently evaluated on the basis of only recovery tests, which exclude sample processing. We studied the effect of sample processing on accuracy and uncertainty of the measured residue values with lettuce, tomato, and maize grain samples applying mixtures of selected pesticides. The results indicate that the method is simple and robust and applicable in any pesticide residue laboratory. The analytes remaining in the final extract are influenced by their physical-chemical properties, the nature of the sample material, the temperature of comminution of sample, and the mass of test portion extracted. Consequently, validation protocols should include testing the effect of sample processing, and the performance of the complete method should be regularly checked within internal quality control.

A survey of coagulation laboratory practices and satisfaction ratings of member laboratories of the Thailand National External Quality Assessment Scheme for blood coagulation

INTRODUCTION

The Thailand National External Quality Assessment Scheme (NEQAS) for blood coagulation was established in 2005. The objective of this study was to collect data of coagulation laboratory practices and satisfaction of NEQAS member.

METHODS

Two hundred seventy-six questionnaires were sent to laboratories that are members of NEQAS to obtain data relating to coagulation laboratory practice and satisfaction in 2014. Data from this survey were compared with data from the survey conducted in 2005 to evaluate levels of improvement.

RESULTS

Of 276 questionnaires sent, 212 (76.8%) were returned. Improvements were characterized by the number of laboratories that (i) decreased use of 3.8% sodium citrate as anticoagulant; (ii) implemented use of at least two control levels for internal quality control; and (iii) implemented reporting of reference values with results, as well as establishing their own reference range and using geometric mean as the denominator for international normalized ratio calculation. For overall satisfaction, 179 of 206 (86.9%) participant laboratories reported being satisfied or very satisfied.

CONCLUSION

Improvements in coagulation laboratory practices in Thailand were observed in every step of the total testing process. However, additional improvements are still needed, such as determination and use of a local reference range.

Quality Control in Screening for Infectious Diseases at Blood Banks. Rationale and Methodology

Quality control procedures are indispensable to ensure the reliability of the results provided by laboratories responsible for serological screening in blood banks. International recommendations on systems of quality management classify as a top component the inclusion of two types of control: (a) internal quality control (IQC) and (b) external quality control (EQC). In EQC it is essential to have, at least, a monthly frequency of laboratory assessment. On the other hand, IQC involves the daily use of low-reactivity control sera, which should be systematically added in all run, carried out in the laboratory for each parameter. Through the IQC analysis some variations in the criteria of run acceptance and rejection may be revealed, but it is of paramount importance to ensure the previous definition of these criteria and even more importantly, the adherence to them; and that corresponds to the validation of analytical runs of each test. Since 2010 this has been, for instance, the experience of the PNCQ*, developing external quality control programmes on serology for blood banks. These programmes use samples of lyophilized sera well-characterized for the reactivity related to the parameters used for the serological screening of blood donors. The programmes have used blind panels of six samples for monthly assessments. In the last 50 assessments, which involved 68 blood banks in Brazil, a significant number of instances of non-compliance were observed in all monthly assessments. These results provide strong support to the recommendation of systematic monthly assessments. (*) National Quality Control Programme (PNCQ).

Imprecision Investigation and Analysis of Routine Chemistry in China

BACKGROUND

This study aims to investigate the imprecision of internal quality control of routine chemistry analytes so that we can have an overall knowledge of imprecision level of measurement in laboratories in China.

METHODS

The internal quality control information including two kinds of coefficient of variations (CVs) of 22 analytes were collected via an on-line questionnaire. Then, the percentages of laboratories meeting the quality requirement for each analyte were calculated according to five imprecision criteria.

RESULTS

Among these 22 analytes, creatine kinase got the most satisfied result, the percentages of laboratories whose current CV met 1/3 total allowable error (1/3TEa), 1/4TEa, and the specifications based on biological variation were 99.3%, 95.9%, 99.6%, 99.9%, and 90.6%, respectively, while Na got the lowest satisfaction rate according to these specifications, which were 4.15%, 22.4%, 4.2%, 9.0%, and 1.3%, respectively. From an overall perspective, most of the 22 analytes got a satisfied result when applying the criteria defined by CLIA'88, while only a small amount of laboratories can meet the requirement when applying the specifications derived from biological variation.

CONCLUSIONS

There is huge space for us to enhance and substantial effort is needed in improving and implementing quality management in China.