National Proficiency Testing Research Articles

The 2023 National Proficiency Test for molecular detection of shrimp infectious myonecrosis virus (IMNV) in China

Infectious myonecrosis virus (IMNV), an emerging virus that can cause severe viral disease in penaeid shrimp, was first confirmed to have spread to China in 2020. In order to standardize diagnostic procedures and reliable detection capability, and to evaluate the performances of aquatic clinical diagnostic laboratories, the competent authority has launched a proficiency test (PT) scheme for the molecular detection of IMNV in China from the year of 2023. In the ring test of IMNV-PT 2023, five tissue samples containing different concentrations of IMNV were provided as a panel of test samples. A total of 68 laboratories participated in the PT test of qualitative and quantitative analysis of the five samples using standard molecular assays. The results showed that 92.65 % (63/68) of the participants correctly reported all samples in the panel using Real-time reverse transcription PCR and 62 participants achieved satisfactory results, one participant using conventional PCR and four participants had not completed the test. Out of the 62 participants in the z-scores analysis, 88.71 % (55/62) achieved acceptable ZB-scores, with two outlier laboratories and five laboratories being questionable. Additionally, 98.39 % (61/62) achieved ZW-scores, with only one laboratory being questionable. Furthermore, the national PT conducted in the present study proved to be an effective tool for evaluating laboratory performance in IMNV molecular testing. This assessment can aid in improving the capabilities of IMNV molecular testing of the participating laboratories, and also provided technical supporting to enhance the national response to IMN outbreaks.

Challenges and improvements in HER2 scoring and histologic evaluation: insights from a national proficiency testing scheme for breast cancer diagnosis in China

BackgroundIn 2022, our team launched the pioneering national proficiency testing (PT) scheme for the pathological diagnosis of breast cancer, rapidly establishing its credibility throughout China. Aiming to continuously monitor and improve the proficiency of Chinese pathologists in breast pathology, the second round of the PT scheme was initiated in 2023, which will expand the number of participating institutions, and will conduct a nationwide investigation into the interpretation of HER2 0, 1+, and 2+/FISH- categories in China.MethodsThe methodology employed in the current round of PT scheme closely mirrors that of the preceding cycle in 2022, which is designed and implemented according to the “Conformity assessment—General requirements for proficiency testing”(GB/T27043—2012/ISO/IEC 17043:2010). More importantly, we utilized a statistics-based method to generate assigned values to enhance their robustness and credibility.ResultsThe final PT results, published on the website of the National Quality Control Center for Cancer (http://117.133.40.88:3927), showed that all participants passed the testing. However, a few institutions demonstrated systemic biases in scoring HER2 0, 1+, and 2+/FISH- with accuracy levels below 59%, considered unsatisfactory. Especially, the concordance rate for HER2 0 cases was only 78.1%, indicating challenges in distinguishing HER2 0 from low HER2 expression. Meanwhile, areas for histologic type and grade interpretation improvement were also noted.ConclusionsOur PT scheme demonstrated high proficiency in diagnosing breast cancer in China. But it also identified systemic biases in scoring HER2 0, 1+, and 2+/FISH- at some institutions. More importantly, our study highlighted challenges in the evaluation at the extreme lower end of the HER2 staining spectrum, a crucial area for further research. Meanwhile, it also revealed the need for improvements in interpreting histologic types and grades. These findings strengthened the importance of robust quality assurance mechanisms, like the nationwide PT scheme conducted in this study, to maintain high diagnostic standards and identify areas requiring further training and enhancement.

Proficiency testing of diagnosis in histopathology and immunohistochemistry of breast pathology in China: results from a pilot work of National Single Disease Quality Control Program for breast cancer

AimPathologists are currently supposed to be aware of both domestic and international guidelines for breast cancer diagnosis, but it is unclear how successfully these guidelines have been integrated into routine clinical practice in China. Thus, this national proficiency testing (PT) scheme for breast pathology was set up to conduct a baseline assessment of the diagnostic capability of pathologists in China.MethodsThis national PT plan is designed and implemented according to the “Conformity assessment—General requirements for proficiency testing” (GB/T27043—2012/ISO/IEC 17043:2010). Five cases of breast cancer with six key items, including histologic type, grade, ER, PR, HER2, and Ki67, were selected for testing among 96 participants. The final PT results were published on the website of the National Quality Control Center for Cancer (http://117.133.40.88:3927/cn/col22/362).ResultsOur study demonstrated that the median PT score was 89.5 (54–100). Two institutions with scores < 67 were deemed unacceptable. The accuracy of histologic type, ER, PR, HER2, and Ki67 was satisfactory (all > 86%). However, the histologic grade showed low accuracy (74.0%). The unacceptable results mainly included incorrect evaluation of histologic grade (36.7%), inaccurate evaluation of ER/PR/HER2/Ki67 (28.2%), incorrect identification of C-AD as IBC-NST (15.7%), inappropriate use of 1+/2+/3+ rather than staining percentage for ER/PR (6.1%), misclassification of ER/PR < 1% weak expression as positive staining (1.4%), and no evaluation of histologic grade in ILC, MC, and IMC (5.8%).Conclusionsour nationwide PT program exhibited a satisfactory baseline assessment of the diagnostic capability of pathologists in China. More importantly, we identify some areas for further improvement.

Development of a national proficiency test for SARS-CoV-2 detection by PCR in Colombia.

Proficiency testing (PT) is a tool for ensuring the validity of results of testing laboratories and is essential when laboratories are working with assays authorised for emergency use or implementing novel techniques for detecting emerging pathogens. In collaboration with the National Health Institute of Colombia and with international support, we developed a qualitative PT for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by reverse transcription polymerase chain reaction (RT-PCR). A proficiency test item (PTI) based on reference material (research grade) produced by the National Institute of Standards and Technologies (NIST) was prepared and characterised using three positive samples with varying concentrations of SARS-CoV-2 ribonucleic acid (RNA) and two negative (control) samples. Tests were distributed to 121 laboratories across the national network of public health laboratories in Colombia. Positive samples had varying concentrations of SARS-CoV-2 RNA and were quantified by digital PCR (RT-ddPCR) assays for the E gene of SARS-CoV-2. We tested the ability of laboratories to detect low and high levels of viral RNA using samples with SARS-CoV-2 RNA concentrations of 1417 ± 216, 146 ± 28, and 14 ± 10 copies /uL (expanded uncertainty, k = 2, 95% confidence level) We also performed a semiquantitative analysis of instrumental responses (Ct values) reported by participating laboratories and homogeneity, stability, and characterisation studies of the produced materials to determine the adequacy of these materials and methods for use in the qualitative PT scheme. The PT evaluated reports for individual target genes from each laboratory; 98.3% of laboratories had satisfactory performance and the remaining 1.7% of laboratories had unsatisfactory performance for the detection of at least one of the reported genes. This PT scheme identified the potential metrological weaknesses of laboratories in the detection of SARS-CoV-2 by RT-PCR and may facilitate improvements in the quality of measurements from the perspective of public health surveillance.

National proficiency test for molecular detection of white spot syndrome virus in China, 2021

National Aquatic Animal Disease Surveillance Program (NAADSP) has started since 2007 to conduct nationwide surveillance for the prevalence of major crustacean pathogens in China, including white spot syndrome virus (WSSV). Standard diagnostic procedures and reliable detection capability are critical for ensuring accurate and comparable surveillance results, hence competent authority of China launched annual proficiency test (PT) synchronously to screen competent aquatic clinical diagnostic laboratories to undertake NAADSP. Here we present the results of PT for molecular detection of WSSV in 2021. Six tissue samples containing different WSSV concentrations were provided as blind samples to a total of 170 laboratories nationwide. All the participating laboratories were asked to perform qualitative or quantitative analyses by using standard molecular assays or commercial detection kits. In the qualitative assessments, 86.8% (125/144) of the participants achieved satisfied results by using conventional nested-PCR. Comparing to the strong/medium positive samples, the identification of negative samples and weak-positive samples have been shown to be more challenging. A relatively higher error rates were reported in results of sample S3 and S4. In the quantitative assessments, cycle threshold (Ct) values of real-time PCR submitted by 47 participants had been analyzed by using robust statistical method. The overall satisfied performance was achieved by 74.5% (35/47) of the participants. Acceptable between-laboratories z-score (ZB) and within-laboratory z-score (ZW) was achieved by 93.3% and 91.1%, respectively, in the analysis of the pair of identical samples S6 and S8. WSSV-PT 2021 supplied valuable reference information for selecting competent laboratories to participate in the NAADSP. Furthermore, the national PT scheme in the study provided an effective tool to access the performance of laboratories in molecular tests, and also gathered practical experience for organizing PTs on other emerging crustacean pathogens in the future.

Statistical Analysis of the Performance of Local Veterinary Laboratories in Molecular Detection (rRT-PCR) of Avian Influenza Virus via National Proficiency Testing Performed during 2020-2022.

For the early detection of avian influenza virus (AIV), molecular diagnostic methods such as real-time RT-PCR (rRT-PCR) are the first choice in terms of accuracy and speed in many countries. A laboratory's capability to perform this diagnostic method needs to be measured through external and independent assessment to ensure that the method is validated within the laboratory and in interlaboratory comparison. The Animal and Plant Quarantine Agency of Korea has implemented five rounds of proficiency testing (PT) for rRT-PCR targeting local veterinary service laboratories involved in the AIV national surveillance program from 2020 to 2022. In each round, a portion composed of six or more samples was selected from the entire PT panel consisting of H5, H7, and H9 viruses isolated in Korea and distributed to each participant, and at least one pair of samples was commonly included in each panel for interlaboratory comparison. During the five rounds of PT, a few incorrect and outlying results were detected that required immediate inspection or corrective actions. However, in the quantitative measurement of Ct values, the average standard deviation or coefficient of variation decreased as multiple PT rounds progressed, and a positive correlation between consecutive rounds of PT was observed since 2021. The better consistency or stability in the experimental performance appeared to contribute to the more harmonized results in the latest PTs, and it is assumed that the positive reaction of participants to the challenges of quantitative assessment reports showing their status intuitively might work. We need to continue operating the PT program for local laboratories because they play crucial roles at the front line of the national avian influenza surveillance program, and frequent changes in the human resources or environment for diagnosis in those laboratories are inevitable.

Evaluation of National Proficiency Testing (PT) Provision in the Scheme of Soil Analysis on PH, Organic Carbon, Total Nitrogen and Available Phosphorus Based On the Same Soil Sample Exchange in Ethiopia

Proficiency testing (PT) is to monitor the quality of their analytical results, demonstrating analytical competence, developing and training analysts, and the validation of methods and instruments as stipulated in ISO/IEC 17025 in Ethiopia. Composite surface soil samples at the depth of 0-20 cm were collected from the experimental sites. The sample was air dried, grained using mortal and pestle and sieved &lt; 0.5mm mesh size. Soil pH, organic carbon, total N and available P were determined at respective agricultural research soil Laboratories following standard lab procedures in fifteen soil laboratories of EIAR &amp; regional centers participated in the PT organized for 2022. The results of the analytical results were evaluated by calculating Z scores.

Improving the quality of HIV rapid testing in Ghana using the dried tube specimen-based proficiency testing program.

BackgroundThe introduction of human immunodeficiency virus (HIV) antibody rapid testing (RT) in resource-limited settings has proven to be a successful intervention to increase access to prevention measures and improve timely linkage to care. However, the quality of testing has not always kept pace with the scale-up of this testing strategy. To monitor the accuracy of HIV RT test results, a national proficiency testing (PT) program was rolled out at selected testing sites in Ghana using the dried tube specimen (DTS) approach.MethodsBetween 2015 and 2018, 635 HIV testing sites, located in five regions and supported by the U.S. President’s Emergency Plan for AIDS Relief (PEPFAR), were enrolled in the HIV PT program of the Ghana Health Service National AIDS/STI Control Programme. These sites offered various services: HIV Testing and Counselling (HTC), prevention of mother-to-child transmission (PMTCT) and Antiretroviral Treatment (ART). The PT panels, composed of six DTS, were prepared by two regional laboratories, using fully characterized plasma obtained from the regional blood banks and distributed to the testing sites. The results were scored by the PT providers according to the predefined acceptable performance criteria which was set at ≥ 95%.ResultsSeven rounds of PT panels were completed successfully over three years. The number of sites enrolled increased from 205 in round 1 (June 2015) to 635 in round 7 (December 2018), with a noticeable increase in Greater Accra and Eastern regions. The average participation rates of enrolled sites ranged from 88.0% to 98.0% across the PT rounds. By round 7, HTC (257/635 (40.5%)) and PMTCT (237/635 (37.3%)) had a larger number of sites that participated in the PT program than laboratory (106/635 (16.7%)) and ART (12/635 (1.9%)) sites. The average testing performance rate improved significantly from 27% in round 1 to 80% in round 7 (p < 0.001). The highest performance rate was observed for ART (100%), HTC (92%), ANC/PMTCT (90%) and Laboratory (89%) in round 5.ConclusionThe DTS PT program showed a significant increase in the participation and performance rates during this period. Sub-optimal performances observed was attributed to non-compliance to the national testing algorithm and testing technique. However, the implementation of review meetings, peer-initiated corrective action, supportive supervisory training, and mentorship proved impactful. The decentralized approach to preparing the PT panels ensured ownership by the region and districts.

Development of a Novel RT-qPCR Detecting Method of Covert Mortality Nodavirus (CMNV) for the National Proficiency Test in Molecular Detection.

Covert mortality nodavirus (CMNV), the pathogen of viral covert mortality disease (VCMD), has caused serious economic losses of shrimp aquaculture in Southeast Asian countries and China in the past decade. In view of that the rapid and accurate laboratory detection of CMNV plays a major role in the effective control of the spread of VCMD. The national proficiency test (NPT) for the detection of covert mortality nodavirus (CMNV) started in China from 2021. In this study, a novel TaqMan real-time reverse transcription quantitative PCR (RT-qPCR) detection method for CMNV with higher sensitivity than previous reports was established based on specific primers and probe designing from the conserved regions of the CMNV coat protein gene for using molecular detection of CMNV in NPT. The optimized RT-qPCR reaction program was determined as reverse transcription at 54.9 °C for 15 min and denaturation at 95 °C for 1 min, followed by 40 cycles including denaturation at 95 °C for 10 s, and annealing and extension at 54.9 °C for 25 s. The detection limit of the newly developed RT-qPCR method was determined to be as low as 2.15 copies of CMNV plasmids template per reaction, with the correlation coefficient (R2) at above 0.99. The new method showed no cross reaction with the six common aquatic animal pathogens and could be finished in one hour, which represents a rapid detection method that can save 50% detection time versus the previously reported assay. The CMNV TaqMan probe based RT-qPCR method developed in present study supplies a novel sensitive and specific tool for both the rapid diagnosing and quantitating of CMNV in NPT activities and in the farmed crustaceans, and will help practitioners in the aquaculture industry to prevent and control VCMD effectively.

The Togo national proficiency test pilot programme for basic clinical chemistry tests.

BackgroundA national proficiency test (PT) programme is not currently implemented in most low-income countries. However, participation in such PT programmes assists improves test performance and result accuracy.ObjectiveThis study assessed how well 11 government hospital laboratories performed 18 basic clinical chemistry tests and identified areas needing improvement.MethodsA cross-sectional study was carried out by the Division of Laboratories of the Ministry of Health of Togo from 01 July 2016 to 31 December 2016. The test performance was evaluated using panels provided by One World Accuracy, Canada (Vancouver). The Clinical Laboratory Improvement Amendments criteria were used in evaluating the laboratories, and their success rates were compared with the World Health Organization Regional Office for Africa’s target of 80%.ResultsThe overall rate of acceptable results at the laboratories was over 80% for glucose, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyltransferase, alkaline phosphatase and triglycerides tests. The laboratories using fully automated spectrophotometers had an acceptable results rate of 89% (p = 0.001). The overall performance of the laboratories by cycles varied from 71% to 82%.ConclusionThis national PT programme identified the tests, which laboratories must improve their performance (urea, creatinine, uric acid, bilirubin, cholesterol, total protein, calcium, magnesium, phosphorus). It demonstrated the need for the use of routine appropriate internal quality control in all laboratories. The proficiency test programme should be extended to all clinical laboratories and target all biology disciplines.

Factors associated with medical students\u2019 self-regulated learning and its relationship with clinical performance: a cross-sectional study

BackgroundThe importance of self-regulated learning (SRL) has been broadly recognised by medical education institutions and medical professionals. Self-regulated learning, which is a context-specific process, is affected by personal, contextual and social factors. Although many studies on exploring the factors that influenced SRL and the relationship of between SRL and clinical achievement levels have been carried out in western countries, little is known about the factors associated with self-regulated learning and its relationship with clinical performance among medical students in China.MethodsA cross-sectional online survey was distributed to 3rd year clinical medicine students who were in the clinical clerkship stage in a medical college in Wuhan. We used Self-regulated Learning Scale for Undergraduates (SLSU) to measure the self-regulated learning of students and Objective Structured Clinical Examination (OSCE) in the national proficiency test to assess the clinical performance of students. The participation rate was 73.95% (193 students). An independent t-test and analysis of variance were used to analyse the factors associated with self-regulated learning. The relationship between self-regulated learning and clinical performance was analysed with multilinear regression analysis.ResultsUnivariate analysis showed that having a clear career planning and a professional idol, providing full-time teaching clinical teachers in the clerkship department and seeking the help of the surrounding classmates and the guidance of teachers or senior students were significant predictors of self-regulated learning. Multilinear regression analysis has revealed a positive relationship among extrinsic goals (partial r = 0.171), clinical clerkship evaluation (partial r = 0.197) and clinical performance (F = 4.070, p = 0.004).ConclusionsMotivation-related personal and social factors related to clinical context could promote the SRL level of medical students in China. Extrinsic goals and clinical clerkship evaluation could facilitate students’ clinical achievements on clinical skills. External support, such as clinical clerkship management, might improve clinical performance on clinical skills in clinical clerkship context.

Measurement of engagement in the foreign language classroom and its effect on language achievement: the case of Chinese college EFL students

Abstract This study developed a comprehensive and domain-specific scale for foreign language classroom engagement (FLCE) and examined the effect of classroom engagement on foreign language achievement. A mixed-methods approach was adopted to gather a broad range of data, including an open-ended questionnaire at the early stage of engagement scale development, the scale itself for pilot study as well as a large-scale survey, and an open-ended questionnaire after the survey to gain further information. A total of 1929 college EFL students across China participated in the large-scale survey. The results revealed that the measurement of FLCE at two levels, one based on the learning context/mode (i.e. individual-based or interaction-based) and the other pertaining to engagement type (i.e. cognitive, behavioral, or emotional), proved to be feasible. While perceiving a moderate level of overall engagement, the students reported significantly higher levels of interaction-based conventional behavioral engagement and individual-based behavioral engagement among the extracted eight facets. Structural equation modelling using English achievement as measured by national proficiency test scores as the dependent variable and the eight engagement dimensions as the independent variables showed an acceptable fit. Among the eight dimensions, only individual-based cognitive engagement significantly predicted the test scores.

Results from a blind comparison of chloride measurements by accredited laboratories and the implications for enforcing increasingly stringent HCl emission limits in EU legislation

ABSTRACT We report results from a blind comparison of six analytical laboratories ISO/IEC 17025 accredited for the implementation of the analytical element of EN 1911, which involves the quantification of chloride in deionized water collected from HCl emitting industrial processes regulated under the EU’s Industrial Emissions Directive (IED). Both “synthetic” (sodium chloride dissolved in deionized water) and “real” (extracted and collected from a stack simulator facility) samples were prepared across ranges which were equivalent to concentrations in the stack of 0–10 mg·m−3 and 0–60 mg·m−3, respectively. Laboratory measurements of the real samples showed significantly poorer performance than the synthetic, implying that the use of synthetic samples in national proficiency testing schemes may be leading to an overly optimistic view of the uncertainties that can routinely be achieved in measurements of real industrial processes. In addition, at the applicable emission limits (10 mg·m−3 and 3 mg·m−3) and measurement ranges (0–15 mg·m−3 and 0–4.5 mg·m−3) under the IED and more recent BAT Conclusions legislation it was found that of the real samples 22 out of 102 (21.6%) and 28 out of 51 (54.9%), respectively, of the measurements would not comply with the overall uncertainty that at least one national regulator considers as necessary for EN 1911 to be an “effective tool” for the calibration of automated measuring systems (AMSs – process plant operator analyzers providing continuous monitoring of emissions). Hence, it is proposed that at the next revision of EN 1911 the standard should be revised to give the same degree of consideration to the analytical element of the method as the sampling element. Key analytical laboratory uncertainty sources should be identified, numerical uncertainty requirements should be placed on key analytical uncertainty sources, and there should be an overall uncertainty requirement for the analytical element. Implications: The deviations observed between laboratories ISO/IEC 17025 accredited for chloride analysis bring into question the ability of the current version of EN 1911 (the CEN Standard Reference Method for monitoring HCl industrial emissions) to meet the uncertainty requirements associated with emission limits under both the EU’s Industrial Emissions Directive and the increasingly stringent industrial sub-sectors BAT Conclusions legislation. It is proposed that at the next revision of EN 1911 that uncertainty guidance and requirements for the analytical element are added if this measurement method is to continue to be mandated across Europe for ensuring emissions data meet legislative quality requirements.

Laboratory testing for fragile X, 2021 revision: a technical standard of the American College of Medical Genetics and Genomics (ACMG)

Molecular genetic testing of the FMR1 gene is commonly performed in clinical laboratories. Pathogenic variants in the FMR1 gene are associated with fragile X syndrome, fragile X–associated tremor ataxia syndrome (FXTAS), and fragile X–associated primary ovarian insufficiency (FXPOI). This document provides updated information regarding FMR1 pathogenic variants, including prevalence, genotype–phenotype correlations, and variant nomenclature. Methodological considerations are provided for Southern blot analysis and polymerase chain reaction (PCR) amplification of FMR1, including triplet repeat–primed and methylation-specific PCR.The American College of Medical Genetics and Genomics (ACMG) Laboratory Quality Assurance Committee has the mission of maintaining high technical standards for the performance and interpretation of genetic tests. In part, this is accomplished by the publication of the document ACMG Technical Standards for Clinical Genetics Laboratories, which is now maintained online (http://www.acmg.net). This subcommittee also reviews the outcome of national proficiency testing in the genetics area and may choose to focus on specific diseases or methodologies in response to those results. Accordingly, the subcommittee selected fragile X syndrome to be the first topic in a series of supplemental sections, recognizing that it is one of the most frequently ordered genetic tests and that it has many alternative methods with different strengths and weaknesses. This document is the fourth update to the original standards and guidelines for fragile X testing that were published in 2001, with revisions in 2005 and 2013, respectively.This versionClarifies the clinical features associated with different FMRI variants (Section 2.3)Discusses important reporting considerations (Section 3.3.1.3)Provides updates on technology (Section 4.1)

National Proficiency Testing of Molecular Diagnostics for Tuberculosis and Drug Resistance Detection - China, 2014-2019.

What is already known about this topic? Proficiency testing (PT) is a key component of quality assurance and is essential in ensuring accurate laboratory diagnosis of tuberculosis (TB) and drug-resistant TB. The National Tuberculosis Reference Laboratory (NTRL) developed a novel PT panel to test laboratories’ proficiency for molecular TB diagnostic assays throughout the TB laboratory network. A total of 6 PT rounds for molecular diagnostics were conducted by NTRL from 2014 to 2019. What is added by this report? PT conducted using artificial sputum specimens increased from 120 in the first round to 1,835 in the sixth round. Overall, laboratories demonstrated good proficiency for MTB and drug-resistance detection by molecular diagnostics, which is evident from the qualification rates over the six rounds: 95%, 97%, 96%, 93%, 93%, and 97%, respectively. What are the implications for public health practice? The use of artificial sputum specimens for PT panel production to test TB molecular diagnostics in China is feasible. Most of the participating laboratories provided reliable molecular diagnostic results for MTB and drug-resistance detection. The TB laboratory network can be instrumental in implementing PT expansion and improving the quality of TB molecular diagnosis in China.

The operating regularity of the stepper motor of thermal inkjet printers and its application in the China national accreditation service 2017ZO146 altered documents identification proficiency test

With the continuous innovation of inkjet printing technology, the methods of using inkjet printers for falsification have also constantly evolved, leading to increasing difficulties in identifying printing alterations made by the same inkjet printer. This paper mainly studies the operating regularity of the stepper motor of inkjet printers to determine the operating mechanism of inkjet printers and thus to identify whether documents had been tampered with. To detect the operating track of the stepper motor, 154 documents printed by 22 different brands and models of thermal inkjet printers were studied according to the periodic morphological characteristics of ink marks and the track of the stepper motor during different printing processes. As a result: ① the maximum gauge of 22 printheads was found to be different and ② the different distribution of ink marks were mainly affected by the direction and speed of the stepper motor. The track of the stepper motor was able to be determined by the periodic morphological characteristics of the ink marks combined with the maximum gauges, and could be used to judge how many times a document was printed. The observed regularities were evaluated by the CNAS 2017ZO146 test, a national proficiency test in China. In conclusion, using the summarized operating regularities of the stepper motor, it is possible to identify printing alterations made by the same thermal inkjet printer.

Monitoring of purity and stability of CRMs of multiclass pesticides during prolonged storage before and after expiration

Certified reference materials (CRMs) are the backbone for qualitative and quantitative determination of pesticides in technical materials, formulations, and food matrices. However, their stringent expiry date, limited shelf life, and diminishing purity with time, limits their use beyond expiry. Stability study of 89 CRMs of multiclass pesticides, stored at − 25 °C, has been conducted to assess the purity of CRMs beyond their expiry date. It was evident that > 96 % of the CRMs remained optimally stable with respect to their observed purity even after their expiry date as per certificate of analysis. Percentage deviations in purity of expired and valid CRMs posited well below 7 % and are within ± 10 % acceptable range as recommended by the SANTE. During 2013–2017, performance of the valid and expired CRMs was evaluated through 44 z-scores obtained in 14 international and national proficiency testing programmes. All the z-scores received for 15 expired and 29 valid CRMs were found satisfactory. Inter-laboratory comparison of 6 randomly selected expired and valid CRMs was tested at three different ISO/IEC 17025 accredited laboratories and their % difference between purities ranged from − 2.35 % to + 0.95 %. It was inferred that by maintaining proper storage conditions and continuous monitoring of purity, the expired CRMs can give comparable results as valid CRMs.

Development of the KOSHA Proficiency Testing Scheme on Asbestos Analysis in Korea.

This commentary presents the regulatory backgrounds and development of the national proficiency testing (PT) scheme on asbestos analysis in the Republic of Korea. Since 2009, under the amended Occupational Safety and Health Act, the survey of asbestos in buildings and clearance test of asbestos removal works have been mandated to be carried out by the laboratories designated by the Ministry of Employment and Labor (MOEL) in the Republic of Korea. To assess the performance of asbestos laboratories, a PT scheme on asbestos analysis was launched by the Korea Occupational Safety and Health Agency (KOSHA) on behalf of the MOEL in 2007. Participating laboratories are evaluated once a year for fiber counting and bulk asbestos analysis by phase contrast microscopy and polarized light microscopy, respectively. Currently, the number of laboratory enrollments is > 200, and the percentage of passed laboratories is > 90. The current status and several significant changes in operation, sample preparations, and statistics of assigning the reference values of the KOSHA PT scheme on asbestos analysis are presented. Critical retrospect based on the experiences of operating the KOSHA PT scheme suggests considerations for developing a new national PT scheme for asbestos analysis.

National Prociency Testing Result of CYP2D6*10 Genotyping for Adjuvant Tamoxifen Therapy in China.

Tamoxifen has been successfully used for treating breast cancer and preventing cancer recurrence. Cytochrome P450 2D6 (CYP2D6) plays a key role in the process of metabolizing tamoxifen to its active moiety, endoxifen. Patients with variants of the CYP2D6 gene may not receive the full benefit of tamoxifen treatment. The CYP2D6*10 variant (the most common variant in Asians) was analyzed to optimize the prescription of tamoxifen in China. To ensure referring clinicians have accurate information for genotype-guided tamoxifen treatment, the Chinese National Center for Clinical Laboratories (NCCL) organized a national proficiency testing (PT) to evaluate the performance of laboratories providing CYP2D6*10 genotyping. Ten genomic DNA samples with CYP2D6 wild-type or CYP2D6*10 variants were validated by PCR-sequencing and sent to 28 participant laboratories. The genotyping results and pharmacogenomic test reports were submitted and evaluated by NCCL experts. Additional information regarding the number of samples tested, the accreditation/certification status, and detecting technology was also requested. Thirty-one data sets were received, with a corresponding analytical sensitivity of 98.2% (548/558 challenges; 95% confidence interval: 96.7–99.1%) and an analytic specificity of 96.5% (675/682; 95% confidence interval: 97.9–99.5%). Overall, 25/28 participants correctly identified CYP2D6*10 status in 10 samples; however, two laboratories made serious genotyping errors. Most of the essential information was included in the 20 submitted CYP2D6*10 test reports. The majority of Chinese laboratories are reliable for detecting the CYP2D6*10 variant; however, several issues revealed in this study underline the importance of PT schemes in continued external assessment and provision of guidelines.

Implementation of Cell Samples as Controls in National Proficiency Testing for Clopidogrel Therapy-Related CYP2C19 Genotyping in China: A Novel Approach.

Laboratories are increasingly requested to perform CYP2C19 genetic testing when managing clopidogrel therapy, especially in patients with acute coronary syndrome undergoing percutaneous coronary intervention. To ensure high quality molecular testing and ascertain that the referring clinician has the correct information for CYP2C19 genotype–directed antiplatelet therapy, a proficiency testing scheme was set up to evaluate the laboratory performance for the entire testing process. Proficiency panels of 10 cell samples encompassing the common CYP2C19 genetic polymorphisms were distributed to 62 participating laboratories for routine molecular testing and the responses were analyzed for accuracy of genotyping and the reporting of results. Data including the number of samples tested, the accreditation/certification status, and test methodology of each individual laboratory were also reviewed. Fifty-seven of the 62 participants correctly identified the CYP2C19 variants in all samples. There were six genotyping errors, with a corresponding analytical sensitivity of 98.5% (333/338 challenges; 95% confidence interval: 96.5–99.5%) and an analytic specificity of 99.6% (281/282; 95% confidence interval: 98.0–99.9%). Reports of the CYP2C19 genotyping results often lacked essential information. In conclusion, clinical laboratories demonstrated good analytical sensitivity and specificity; however, the pharmacogenetic testing community requires additional education regarding the correct reporting of CYP2C19 genetic test results.