[Analysis on vitamin B_1 and vitamin B_2 proficiency testing assessment in China disease control and prevention system].

OBJECTIVE: To evaluate the detection ability of vitamin B_1 and vitamin B_(2 )in rice flour in the laboratories of disease control and prevention system, by conducting the proficiency testing(PT)activity. METHODS: Before the vitamin B_1 and vitamin B_2 quality control samples were distributed to the laboratories of disease control and prevention system, the uniformity and stability of samples were analyzed by one-way ANOVO respectively. High performance liquid chromatography(HPLC) method was required to determine vitamin B_1(GB 5009.84-2016: determination of vitamin B_1 in food, first method as reference). HPLC method was also required to determine vitamin B_2(GB 5009.85-2016: determination of vitamin B_2 in food, first method as reference). Robust statistics analysis of proficiency testing result was conducted to evaluate laboratory testing ability through Z score. RESULTS: A total of 43 laboratories completed the proficiency testing. In all of the laboratories participated in the determination of vitamin B_(1 )and vitamin B_2, the total satisfactory rate of vitamin B_1 was 88.4%, while vitamin B_2 was 86.0%. CONCLUSION: The ability of vitamin B_1 and vitamin B_2 detection in disease control and prevention system in China is better than expected, and the testing ability of a few laboratory needs to be improved.

Recommendations for Setting a Criterion and Assessing Commutability of Sample Materials Used in External Quality Assessment/Proficiency Testing Schemes.

It is important for external quality assessment materials (EQAMs) to be commutable with clinical samples; i.e., they should behave like clinical samples when measured using end-user clinical laboratory in vitro diagnostic medical devices (IVD-MDs). Using commutable EQAMs makes it possible to evaluate metrological traceability and/or equivalence of results between IVD-MDs. The criterion for assessing commutability of an EQAM between 2 IVD-MDs is that its result should be within the prediction interval limits based on the statistical distribution of the clinical sample results from the 2 IVD-MDs being compared. The width of the prediction interval is, among other things, dependent on the analytical performance characteristics of the IVD-MDs. A presupposition for using this criterion is that the differences in nonselectivity between the 2 IVD-MDs being compared are acceptable. An acceptable difference in nonselectivity should be small relative to the analytical performance specifications used in the external quality assessment scheme. The acceptable difference in nonselectivity is used to modify the prediction interval criterion for commutability assessment. The present report provides recommendations on how to establish a criterion for acceptable commutability for EQAMS, establish the difference in nonselectivity that can be accepted between IVD-MDs, and perform a commutability assessment. The report also contains examples for performing a commutability assessment of EQAMs.

Neoplastic Cellularity Assessment in Molecular Testing.

CONTEXT.­: Neoplastic cellularity assessment has become an essential component of molecular oncology testing; however, there are currently no best practice recommendations or guidelines for this potentially variable step in the testing process. OBJECTIVE.­: To describe the domestic and international practices of neoplastic cellularity assessment and to determine how variations in laboratory practices affect neoplastic cellularity assessment accuracy. DESIGN.­: Data were derived from 57 US and international laboratories that participated in the 2019 College of American Pathologists Neoplastic Cellularity Proficiency Testing Survey (NEO-B 2019). NEO-B 2019 included 29 laboratory practice questions and 5 images exhibiting challenging histologic features. Participants assessed the neoplastic cellularity of hematoxylin-eosin-stained digital images, and results were compared to a criterion standard derived from a manual cell count. RESULTS.­: The survey responses showed variations in the laboratory practices for the assessment of neoplastic cellularity, including the definition of neoplastic cellularity, assessment methodology, counting practices, and quality assurance practices. In some instances, variation in laboratory practice affected neoplastic cellularity assessment performance. CONCLUSIONS.­: The results highlight the need for a consensus definition and improved standardization of the assessment of neoplastic cellularity. We put forth an initial set of best practice recommendations to begin the process of standardizing neoplastic cellularity assessment.

External quality assessment of serum indices: Spanish SEQC-ML program.

OBJECTIVES: Serum indices included in clinical chemistry instruments are widely used by laboratories to assess the quality of samples. Instruments that report quantitative results allow an evaluation of their diagnostic performance in a similar way to other biochemical tests. The Spanish Society of Laboratory Medicine (SEQC-ML) launched a monthly External Quality program of serum indices in 2018 using three lyophilized materials of simultaneous annual distribution. We present the results of the first three years of the program. METHODS: The use of four different quality control materials with different concentrations in three alternate months allows an annual evaluation of the participant's accuracy. Assigned values are established by consensus among homogeneous groups, considering necessary at least 10 participants for a comparison at instrument level. The average percentage difference results per instrument allow the assessment of bias among groups. RESULTS: The imprecision of the three indices ranges between 3 and 9%, with no major differences among instruments. Significant differences were observed in all indices among instruments with more than 10 participants (Roche Cobas, Abbott Architect, Abbott Alinity and Siemens Advia). The 90th percentile of the distribution of percentage differences was used as the analytical performance specification (APS). An improvement in performance was observed in the first three years of the program, probably due to the learning curve effect. In 2020, APS of 7.8, 12.2 and 9.7% were proposed for hemolytic, icteric and lipemic indices, respectively. CONCLUSIONS: Serum indices have a great impact on the quality and the reliability of laboratory test results. Participation in proficiency testing programs for serum indices is helpful to encourage harmonization among providers and laboratories.

External quality assessment in the absence of proficiency testing: A split-sample testing program experience.

In the field of laboratory medicine, proficiency testing is a vehicle used to improve the reliability of reported results. When proficiency tests are unavailable for a given analyte, an alternative approach is required to ensure adherence to the International Organization for Standardization (ISO) 15189:2012 standard. In this study, we report the results of a split-sample testing program performed as an alternative to a formal PT. This testing method was based on recommendations provided in the Clinical and Laboratory Standards Institute (CLSI) QMS24 guideline. Two different laboratories measured, in duplicate, the heparan sulfate concentration in five samples using ultra-performance liquid chromatography and tandem mass spectrometry. The data analysis to determine the criterion used for the comparability assessment between the two laboratories was based on Appendix E of the QMS24 guideline. Mean interlaboratory differences fell within the maximum allowable differences calculated from the application of the QMS24 guideline, indicating that the results obtained by the two laboratories were comparable across the concentrations tested. Application of the QMS24 split-sample testing procedure allows laboratories to objectively assess test results, thus providing the evidence needed to face an accreditation audit with confidence. However, due to the limitations of statistical analyses in small samples (participants and/or materials), laboratory specialists should assess whether the maximum allowable differences obtained are suitable for the intended use, and make adjustments if necessary.

Assessment of droplet digital polymerase chain reaction for measuring BCR-ABL1 in chronic myeloid leukaemia in an international interlaboratory study.

Measurement of BCR activator of RhoGEF and GTPase -ABL proto-oncogene 1, non-receptor tyrosine kinase (BCR-ABL1) mRNA levels by reverse transcription quantitative polymerase chain reaction (RTqPCR) has been critical to treatment protocols and clinical trials in chronic myeloid leukaemia; however, interlaboratory variation remains a significant issue. Reverse transcriptase droplet digital PCR (RTddPCR) has shown potential to improve testing but a large-scale interlaboratory study is required to definitively establish this. In the present study, 10 BCR-ABL1-positive samples with levels ranging from molecular response (MR)1·0 -MR5·0 were tested by 23 laboratories using RTddPCR with the QXDX BCR-ABL %IS kit. A subset of participants tested the samples using RTqPCR. All 23 participants using RTddPCR detected BCR-ABL1 in all samples to MR4·0 . Detection rates for deep-response samples were 95·7% at MR4·5 , 78·3% at MR4·7 and 87·0% at MR5·0 . Interlaboratory coefficient of variation was indirectly proportional to BCR-ABL1 level ranging from 29·3% to 69·0%. Linearity ranged from 0·9330 to 1·000 (average 0·9936). When results were compared for the 11 participants who performed both RTddPCR and RTqPCR, RTddPCR showed a similar limit of detection to RTqPCR with reduced interlaboratory variation and better assay linearity. The ability to detect deep responses with RTddPCR, matched with an improved linearity and reduced interlaboratory variation will allow improved patient management, and is of particular importance for future clinical trials focussed on achieving and maintaining treatment-free remission.

A Comprehensive Approach to Assuring Quality of Laboratory Testing in HIV Surveys: Lessons Learned From the Population-Based HIV Impact Assessment Project.

BACKGROUND: Conducting HIV surveys in resource-limited settings is challenging because of logistics, limited availability of trained personnel, and complexity of testing. We described the procedures and systems deemed critical to ensure high-quality laboratory data in the population-based HIV impact assessments and large-scale household surveys. METHODS: Laboratory professionals were engaged in every stage of the surveys, including protocol development, site assessments, procurement, training, quality assurance, monitoring, analysis, and reporting writing. A tiered network of household, satellite laboratories, and central laboratories, accompanied with trainings, optimized process for blood specimen collection, storage, transport, and real-time monitoring of specimen quality, and test results at each level proved critical in maintaining specimen integrity and high-quality testing. A plausibility review of aggregate merged data was conducted to confirm associations between key variables as a final quality check for quality of laboratory results. RESULTS: Overall, we conducted a hands-on training for 3355 survey staff across 13 surveys, with 160-387 personnel trained per survey on biomarker processes. Extensive training and monitoring demonstrated that overall, 99% of specimens had adequate volume and 99.8% had no hemolysis, indicating high quality. We implemented quality control and proficiency testing for testing, resolved discrepancies, verified >300 Pima CD4 instruments, and monitored user errors. Aggregate data review for plausibility further confirmed the high quality of testing. CONCLUSIONS: Ongoing engagement of laboratory personnel to oversee processes at all levels of the surveys is critical for successful national surveys. High-quality population-based HIV impact assessments laboratory data ensured reliable results and demonstrated the impact of HIV programs in 13 countries.

Recent Trends in Creatinine Assays in Korea: Long-Term Accuracy-Based Proficiency Testing Survey Data by the Korean Association of External Quality Assessment Service (2011-2019).

BACKGROUND: Accurate serum creatinine (Cr) concentration measurement is essential for evaluating kidney function. In 2011, the Korean Association of External Quality Assessment Service (KEQAS) launched an accuracy-based Cr proficiency testing (ABCr PT) survey. We analyzed long-term data of the KEQAS ABCr PT survey collected between 2011 and 2019 to assess recent trends in Cr assays in Korea. METHODS: The ABCr PT survey including three commutable fresh-frozen serum samples was performed twice a year. The target Cr concentration was assigned using isotope-dilution mass spectrometry. We analyzed data obtained from the participating laboratories, calculated the yearly bias, and evaluated bias trends for the major reagents and instruments. Outliers were excluded from all analysis. RESULTS: The mean percentage bias based on the total data of all participating laboratories was 10.8% in the 2011-A survey and 0.2% in 2019-B survey. Bias for the major reagents and instruments differed depending on the manufacturer. Enzymatic assays generally showed desirable bias ranging from -3.9% to 3.2% at all Cr concentrations and lower interlaboratory variability than non-enzymatic assays (enzymatic vs. non-enzymatic, 3.3%-7.2% vs. 6.3%-9.1%). CONCLUSIONS: Although the mean percentage bias of Cr assays tends to decrease over time, it is necessary to continuously strive to improve Cr assay accuracy, especially at low concentrations.

The use of dried tube specimens of Plasmodium falciparum in an external quality assessment programme to evaluate health worker performance for malaria rapid diagnostic testing in healthcare centres in Togo.

BACKGROUND: The use of rapid diagnostic tests (RDTs) to diagnose malaria is common in sub-Saharan African laboratories, remote primary health facilities and in the community. Currently, there is a lack of reliable methods to ascertain health worker competency to accurately use RDTs in the testing and diagnosis of malaria. Dried tube specimens (DTS) have been shown to be a consistent and useful method for quality control of malaria RDTs; however, its application in National Quality Management programmes has been limited. METHODS: A Plasmodium falciparum strain was grown in culture and harvested to create DTS of varying parasite density (0, 100, 200, 500 and 1000 parasites/µL). Using the dried tube specimens as quality control material, a proficiency testing (PT) programme was carried out in 80 representative health centres in Togo. Health worker competency for performing malaria RDTs was assessed using five blinded DTS samples, and the DTS were tested in the same manner as a patient sample would be tested by multiple testers per health centre. RESULTS: All the DTS with 100 parasites/µl and 50% of DTS with 200 parasites/µl were classified as non-reactive during the pre-PT quality control step. Therefore, data from these parasite densities were not analysed as part of the PT dataset. PT scores across all 80 facilities and 235 testers was 100% for 0 parasites/µl, 63% for 500 parasites/µl and 93% for 1000 parasites/µl. Overall, 59% of the 80 healthcare centres that participated in the PT programme received a score of 80% or higher on a set of 0, 500 and 1000 parasites/ µl DTS samples. Sixty percent of health workers at these centres recorded correct test results for all three samples. CONCLUSIONS: The use of DTS for a malaria PT programme was the first of its kind ever conducted in Togo. The ease of use and stability of the DTS illustrates that this type of samples can be considered for the assessment of staff competency. The implementation of quality management systems, refresher training and expanded PT at remote testing facilities are essential elements to improve the quality of malaria diagnosis.

Nationwide proficiency assessment of bacterial identification and antimicrobial susceptibility testing among 110 laboratories in Lebanon.

INTRODUCTION: Proficiency testing (PT) is one of the most valuable and important activities for the Clinical Microbiology Laboratories (CML) to enroll in to ensure the accuracy and reliability of results. This first time conducted nationwide study was warranted to assess the PT performance activity among CML in Lebanon. METHODOLOGY: Four training and PT activities were organized for 110 nationwide laboratories involved in providing clinical microbiology services. In each PT activity, five different bacterial species were distributed to each laboratory to provide identification (ID) and antimicrobial susceptibility testing (AMST) according to prior discussions and guidelines. RESULTS: The percentages of labs that correctly identified the bacterial species and performed the relevant AMST to it, respectively, were as follows: S. aureus, (100% and 67.8%); Enterococcus faecalis (71% and 82%); Listeria monocytogenes (75% and 61%); Streptococcus agalactiae (86% and 71%); Corynebacterium amycolatum (7% and 33 %); Pseudomonas aeruginosa, (93 % and 53.4%); Klebsiella pneumoniae, (97% and 67.7%); Salmonella typhi ESBL (87 % and 66%); Enterobacter aerogenes (89% and 59%) and Stenotrophomonas maltophilia (84 % and 65%). The resistant types for the species were specified by labs as carbapenem resistant (CR) K. pneumoniae in 78 %, CR E. aerogenes in 34 %, MRSA in 83 %, and VRE in 80.5%. CONCLUSIONS: The wide variation as well as the overall humble scoring of accurate results reflects the dire need for the MOPH to establish and maintain a PT activity program, and entrust the reference laboratory to provide continuing education and training sessions.

External quality assessment (EQA) of Neisseria gonorrhoeae antimicrobial susceptibility testing in primary laboratories in Germany.

BACKGROUND: Worldwide, an increase in antimicrobial resistance (AMR) of Neisseria gonorrhoeae has been observed. Until now, no protocol for an external quality assessment (EQA) has been available for Germany. The German gonococcal resistance network (GORENET) performed an EQA of primary laboratories in Germany in order to assess quality of antibiotic susceptibility testing, to gain information about laboratory procedures and to assess the impact of these procedures on test results. METHODS: Laboratories assessed drug susceptibility to cefixime, ceftriaxone, azithromycin, penicillin and ciprofloxacin for five N. gonorrhoeae strains, using their standard laboratory protocols. Minimal inhibitory concentrations (MICs) were compared to World Health Organisation (WHO) consensus results (or, if not available, reference laboratory results), while deviation by +/- one doubling dilution was accepted. Data on laboratory procedures were collected via a standardised questionnaire. Generalized linear models and conditional inference trees (CTREE) were used to assess relationships between laboratory procedures and testing outcomes. RESULTS: Twenty-one primary laboratories participated in the EQA in June 2018. 96% of ciprofloxacin MICs were reported within accepted deviations, as well as 88% for cefixime, 85% for ceftriaxone, 79% for penicillin and 70% for azithromycin. The use of interpretation standards and general laboratory procedures like agar base, incubation settings or the use of control strains strongly differed between laboratories. In statistical analysis, incubation time of cultures < 24 h was associated with correct measurements. Additionally, a 5% CO2 concentration was associated with correct results regarding azithromycin compared to 3%. CTREE analysis showed that incubation time, humidity and CO2 concentration had the greatest influence on the average deviation from consensus results. CONCLUSIONS: In conclusion, we report the development of a protocol for N. gonorrhoeae antimicrobial susceptibility testing in Germany. While testing results were in accordance with the expected consensus results in 70-96%, depending on the antibiotic agent, laboratory methodology was heterogeneous and may significantly affect the testing quality. We therefore recommend the development of a standard operating procedure (SOP) for N. gonorrhoeae susceptibility testing in Germany.

Nationwide External Quality Assessment of SARS-CoV-2 Molecular Testing, South Korea.

External quality assessment (EQA) is essential for ensuring reliable test results, especially when laboratories are using assays authorized for emergency use for newly emerging pathogens. We developed an EQA panel to assess the quality of real-time reverse transcription PCR assays being used in South Korea to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With the participation of 23 public health organization laboratories and 95 nongovernmental laboratories involved in SARS-CoV-2 testing, we conducted qualitative and semiquantitative performance assessments by using pooled respiratory samples containing different viral loads of SARS-CoV-2 or human coronavirus OC43. A total of 110 (93.2%) laboratories reported correct results for all qualitative tests; 29 (24.6%) laboratories had >1 outliers according to cycle threshold values. Our EQA panel identified the potential weaknesses of currently available commercial reagent kits. The methodology we used can provide practical experience for those planning to conduct evaluations for testing of SARS-CoV-2 and other emerging pathogens in the future.

First results of a national external quality assessment scheme for the detection of SARS-CoV-2 genome sequences.

BACKGROUND: Broad and decentralised testing of SARS-CoV-2 RNA genomes is a WHO-recommended strategy to contain the SARS-CoV-2 pandemic by identifying infected cases in order to minimize onward transmission. With the need to increase the test capacities in Austria, nation-wide numerous laboratories rapidly implemented assays for molecular detection of SARS-CoV-2 based on real-time RT-PCR assays. The objective of this study was to monitor reliability of the laboratory results for SARS-CoV-2 RNA detection through an external quality assessment (EQA) scheme. METHODS: For this, the Center for Virology, Medical University of Vienna was tasked by the Federal Ministry of Social Affairs, Health, Care and Consumer Protection to perform the first Austrian EQA on SARS-CoV-2 which was organised in cooperation with the Austrian Association for Quality Assurance and Standardization of Medical and Diagnostic Tests (ÖQUASTA). Data were analysed on the basis of qualitative outcome of testing in relation to the nucleic acid (NA) extraction and detection methods used. RESULTS AND CONCLUSION: A total of 52 laboratories participated, contributing results from 67 test panels comprising 42 distinct combinations of NA extraction and PCR reagents. By testing 3 positive (CT values: S1, 28.4; S2, 33.6; S3, 38.5) and 1 negative sample, no false-positive results were obtained by any of the laboratories. Otherwise, 40/67 tests (60 %) detected all positive samples correctly as positive, but 25/67 tests (37 %) did not detect the weakest positive sample (S3), and 3 % reported S2 and S3 as false-negative. Improvement in test sensitivity by focusing on NA extraction and/or PCR-based detection is recommended.

Comprehensive competency assessment of malaria microscopists and laboratory diagnostic service capacity in districts stratified for malaria elimination in Ethiopia​.

BACKGROUND: Federal Ministry of Health (FMoH) Ethiopia achieved significant declines in malaria mortality and incidence and has recently launched malaria elimination in selected low transmission settings. Successful malaria elimination calls for rapid and accurate diagnosis of cases so that the patients can promptly be treated before the occurrence of transmission. Therefore, this study assessed the competency of malaria microscopists using panal slides, and laboratory service availability and readiness in terms of supplies and equipments in malaria elimination targeted districts in Ethiopia. METHOD: A cross-sectional study was conducted from February to June 2018 in all hospitals, health centers and private clinics in 20 malaria elimination targeted districts, selected out of the 6 regional states in Ethiopia. All malaria microscopists available in the study health facilities during the study period were included in the study. Questionnaires were used for interviewing sociodemography of personnel and laboratory supplies. Per World Health Organization (WHO) criteria set for proficiency testing, 10 Giemsa stained malaria slide panels (8 positive low/high density pf/pv/Mixed and 2 negative slides) were administered to each study participant for performance assessment on malaria parasite detection, species identification and parasite count using light microscopy. The slide panels are PCR confirmed and WHO approved ones, which have been stored in the slide banks at the national reference laboratory in Ethiopian Public Health Institute. RESULT: In this assessment, 17(16%) district hospitals, 71(67%) health centers (HCs) and 18(17%) private clinics (PCs) were included. Of the 18 PCs, only 10(55.6%) had license certificate. Of the study facilities, 91.5%(97) use light microscopy, 2.83%(3) use RDTs and 2.9%(3) use both microscopy and RDT to detect malaria. Accessible and appropriate storage of Giemsa was reported by 58.8%(10) hospitals, 81.7%(58) HCs & 72.2%(13) private clinics. Of the 1896 malaria positive & 474 negative slides administered to 237 study participants, 318(16.8%) slides reported falsely negative & 47(9.9%) reported falsely positive. The participants achieved "good" grade [Agreement(A): 84.6%, Kappa(K): 0.6] on parasite detection and "poor" agreement (A: 43.8%; K: 0.11) on every species identification. No or slight agreement seen on differentiation of P. falciparum from other species (A: 28.41%; K:0.29). Above 95%(201) of participants, did not count or used plus system of parasite estimation which is the least accurate and unreccomended method per WHO guideline. CONCLUSION: In the current study, low performance of malaria microscopists particularly in species identification & poor to moderate capacity of laboratories observed. This is really a great obstacle to malaria elimination strategy of the country. Therefore, national malaria control and elimination program in collaboration with partners is supposed to provide comprehensive training for professionals giving laboratory service and to fulfill laboratory supplies to have the gold standard service.

First international external quality assessment scheme of nucleic acid amplification tests for the detection of Schistosoma and soil-transmitted helminths, including Strongyloides: A pilot study.

BACKGROUND: Nucleic acid amplification tests (NAATs) are increasingly being used as diagnostic tools for soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, Necator americanus, Ancylostoma duodenale and A. ceylanicum), Strongyloides stercoralis and Schistosoma in human stool. Currently, there is a large diversity of NAATs being applied, but an external quality assessment scheme (EQAS) for these diagnostics is lacking. An EQAS involves a blinded process where test results reported by a laboratory are compared to those reported by reference or expert laboratories, allowing for an objective assessment of the diagnostic performance of a laboratory. In the current study, we piloted an international EQAS for these helminths (i) to investigate the feasibility of designing and delivering an EQAS; (ii) to assess the diagnostic performance of laboratories; and (iii) to gain insights into the different NAAT protocols used. METHODS AND PRINCIPAL FINDINGS: A panel of twelve stool samples and eight DNA samples was validated by six expert laboratories for the presence of six helminths (Ascaris, Trichuris, N. americanus, Ancylostoma, Strongyloides and Schistosoma). Subsequently this panel was sent to 15 globally dispersed laboratories. We found a high degree of diversity among the different DNA extraction and NAAT protocols. Although most laboratories performed well, we could clearly identify the laboratories that were poorly performing. CONCLUSIONS/SIGNIFICANCE: We showed the technical feasibility of an international EQAS for the NAAT of STHs, Strongyloides and Schistosoma. In addition, we documented that there are clear benefits for participating laboratories, as they can confirm and/or improve the diagnostic performance of their NAATs. Further research should aim to identify factors that explain poor performance of NAATs.

External Quality Assessment for Next-Generation Sequencing-Based HIV Drug Resistance Testing: Unique Requirements and Challenges.

Over the past decade, there has been an increase in the adoption of next generation sequencing (NGS) technologies for HIV drug resistance (HIVDR) testing. NGS far outweighs conventional Sanger sequencing as it has much higher throughput, lower cost when samples are batched and, most importantly, significantly higher sensitivities for variants present at low frequencies, which may have significant clinical implications. Despite the advantages of NGS, Sanger sequencing remains the gold standard for HIVDR testing, largely due to the lack of standardization of NGS-based HIVDR testing. One important aspect of standardization includes external quality assessment (EQA) strategies and programs. Current EQA for Sanger-based HIVDR testing includes proficiency testing where samples are sent to labs and the performance of the lab conducting such assays is evaluated. The current methods for Sanger-based EQA may not apply to NGS-based tests because of the fundamental differences in their technologies and outputs. Sanger-based genotyping reports drug resistance mutations (DRMs) data as dichotomous, whereas NGS-based HIVDR genotyping also reports DRMs as numerical data (percent abundance). Here we present an overview of the need to develop EQA for NGS-based HIVDR testing and some unique challenges that may be encountered.

Good staining quality ensuring the reproducibility of Ki67 assessment.

AIMS: Although Ki67 labelling index (LI) is a prognostic and predictive marker in breast cancer, its accuracy and reproducibility must be validated before its clinical application. We aimed to evaluate the agreement of Ki67 LI in clinical practice in Taiwan. METHODS: We conducted a Ki67 immunohistochemistry (IHC) proficiency test. The participants performed the Ki67 IHC test and measured the Ki67 LI of 10 cases of breast cancer tissue on a microarray slide. The staining quality was centrally reviewed based on the Ki67 staining of the tonsil surface epithelium. RESULTS: Ki67 staining and counting methods are diverse in Taiwan. The reproducibility of Ki67 LI was poor to good (intraclass correlation coefficient: 0.581, 95% CI 0.354 to 0.802). The reproducibility and agreement in the high staining quality group were significantly higher than those in the low staining quality group. The majority of the Ki67 LIs derived from the low staining quality group were underestimated. Different counting methods did not reveal significant differences when determining Ki67 LI with microarray sections. CONCLUSIONS: We suggest using the surface epithelium of the tonsil as external control and achieving optimal staining results that consist of a high positive parabasal layer, a low positive intermediate layer and a negative superficial layer. Good Ki67 staining quality can minimise the staining variations among different laboratories, and it is essential for the reproducibility of Ki67 LI.

Proficiency test for rabies serology: A design complying with international standards for a reliable assessment of participating laboratories.

BACKGROUND: Domestic carnivores can introduce rabies into disease-free countries or areas if they are incubating the disease and transported during the pre-symptomatic period. For pets moved into the European Union, the European Commission decided to establish a system of community approval of laboratories willing to carry out the rabies serological controls to guarantee an effective control system. As the specific institute to coordinate the approval of the laboratories, designated by the European Commission in 2000, our laboratory organizes annual proficiency tests (PT) for laboratories already agreed or willing to be agreed to perform rabies serological controls (by detecting rabies virus neutralizing antibodies only) in the frame of international trade. METHODOLOGY/PRINCIPAL FINDINGS: The assessment criteria of this PT rely on the analysis of the specificity and the intra-laboratory consistency. The approach used to evaluate the degree of laboratory consistency is based on the use of compiled data obtained from previous PT campaigns, and is measured by the quality of a regression model. By using historical data for calculating assigned values and associated standard deviations, instead of values obtained from only one campaign, they became robust without any additional statistical treatment. In the present paper, more than 800 historical values were compiled for each of the regression parameters. CONCLUSIONS/SIGNIFICANCE: Since the beginning of these PT schemes in 1999, the overall percentage of failing laboratories remained stable over the years (4.1%) while the number of participants increased to 79 in 2018. This highlighted the robustness and the consistency of the statistical analyses used to assess the laboratory's performance over the years. The improvements carried out and the consistency of our statistical analyses have resulted in the compliance of the rabies serology PT with the ISO/IEC 17043 and ISO 13528:2015 International Standards.