Royal College Of Pathologists Of Australasia Quality Assurance Programs Research Articles

Update on methods used for mycological testing: wide diversity and opportunities for improvement persist

Past analysis of laboratory methods used for mycology specimens revealed significant variation in practices, many of which fell short of recommended procedures. In 2016 these findings led to a set of recommendations for laboratories to consider modification of their methods where appropriate, to analyse current laboratory methods used by participants in the Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) Mycology module, and to compare these to the 2016 recommendations. Seven test items, with 105-107 participants each, were analysed. Several laboratories (7-12%) did not handle specimens as recommended in an appropriate biological safety cabinet. Direct microscopy was not performed on tissue specimens 23-25% of the time. The most used staining method was potassium hydroxide with an optical brightener for fluorescent microscopy (49%) followed by Gram stain (33%). While 17-25% of laboratories used three or more media, use of four or more was uncommon (<3%). Between 9-13% of participants used only a single non-inhibitory medium for cultures. Urine specimens were incubated longer than recommended with 57% of laboratories incubating for >7days and 24% >21 days. Duration of incubation was shorter than recommended for several specimen types with 36% of skin specimens and 37-48% of tissue specimens being kept ≤21 days. For cultures kept >7 days, 13% were inspected daily but for those incubating >14 days only 3%. The methods of several laboratories remain outside recommended practice. An updated set of recommendations are made.

External Quality Assessment (EQA) for SARS-CoV-2 RNA Point-of-Care Testing in Primary Healthcare Services: Analytical Performance over Seven EQA Cycles.

In April 2020, the Aboriginal and Torres Strait Islander COVID-19 Point-of-Care (POC) Testing Program was initiated to improve access to rapid molecular-based SARS-CoV-2 detection in First Nations communities. At capacity, the program reached 105 health services across Australia. An external review estimated the program contributed to averting between 23,000 and 122,000 COVID-19 infections within 40 days of the first infection in a remote community, equating to cost savings of between AU$337 million and AU$1.8 billion. Essential to the quality management of this program, a customised External Quality Assessment (EQA) program was developed with the Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP). From July 2020 to May 2022, SARS-CoV-2 EQA participation ranged from 93 to 100%. Overall concordance of valid EQA results was high (98%), with improved performance following the first survey. These results are consistent with those reported by 12 Australian and 4 New Zealand laboratories for three SARS-CoV-2 RNA EQA surveys in March 2020, demonstrating that SARS-CoV-2 RNA POC testing in primary care settings can be performed to an equivalent laboratory analytical standard. More broadly, this study highlights the value of quality management practices in real-world testing environments and the benefits of ongoing EQA program participation.

Blood culture quality assurance: findings from a RCPAQAP Key Incident Monitoring and Management Systems (KIMMS) audit of blood culture performance

Blood cultures (BC) are the gold standard investigation for bloodstream infection. Standards exist for BC quality assurance, but key quality indicators are seldom measured. The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) Key Incident Monitoring and Management Systems (KIMMS) invited laboratories for the first time to participate in an audit to determine adult BC positivity rates, contamination rates, sample fill volumes and the proportion received as a single set. The overall aim of the KIMMS audit was to provide laboratories with a mechanism for peer review and benchmarking. Results from 45 laboratories were analysed. The majority of laboratories (n=28, 62%) reported a positivity rate outside the recommended range of 8-15%. Contamination rates ranged from zero (n=5) to 12.5%, with seven laboratories (15%) reporting a contamination rate greater than the recommended 3%. Fifteen laboratories (33%) reported an average fill volume of less than the recommended 8-10 mL per bottle, with 11 laboratories (24%) reporting fill volumes of 5 mL or less whilst 13 (28%) laboratories were not able to provide any fill volume data. Thirteen laboratories (29%) reported that 50% or more of BC were received as single set, and eight (17%) were not able to report this data. This audit highlights there are deficiencies in BC quality measures across laboratories. To support BC quality improvement efforts, RCPAQAP KIMMS will offer a yearly BC quality assurance audit to encourage laboratories to monitor their BC quality performance.

Method comparison of antibody titre sensitivity using RCPAQAP datasets

Introduction: The antibody titre offered by the Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) surveys laboratory technical procedures on antibody titres using various methods. A review is performed on reports of the last 5 years to ascertain any differences in sensitivity between various methods employed by laboratories.

Proficiency testing for SARS-CoV-2 in assuring the quality and overall performance in viral RNA detection in clinical and public health laboratories

Diagnostic testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has undergone significant changes over the duration of the pandemic. In early 2020, SARS-CoV-2 specific nucleic acid testing (NAT) protocols were predominantly in-house assays developed based on protocols published in peer reviewed journals. As the pandemic has progressed, there has been an increase in the choice of testing platforms. A proficiency testing program for the detection of SARS-CoV-2 by NAT was provided to assist laboratories in assessing and improving test capabilities in the early stages of the pandemic. This was vital in quality assuring initial in-house assays, later commercially produced assays, and informing the public health response. The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) offered three rounds of proficiency testing for SARS-CoV-2 to Australian and New Zealand public and private laboratories in March, May, and November 2020. Each round included a panel of five specimens, consisting of positive (low, medium or high viral loads), inconclusive (technical specimen of selected SARS-CoV-2 specific genes) and negative specimens. Results were received for round 1 from 16, round 2 from 97 and round 3 from 101 participating laboratories. Improvement in the accuracy over time was shown, with the concordance of results in round 1 being 75.0%, in round 2 above 95.0% for all samples except one, and for round 3 above 95.0%. Overall, participants demonstrated high capabilities in detecting SARS-CoV-2, even in samples of low viral load, indicating excellent testing accuracy and therefore providing confidence in Australian and New Zealand public and private laboratories test results.

Rapid On-Site Evaluation Technical Exercise Using Digital Pathology: Peer Comparison in an External Quality Assurance Setting

Background: The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) is a world leader in the provision of external quality assurance (EQA) for pathology laboratories. The development and delivery of new programmes are designed to meet the evolving needs of our participants and pathology practice. A cytopathology technical programme was established in 2018 to provide proficiency testing in routine cytopreparatory techniques. The cytopathology technical pilot focused on standard operating procedures and laboratory performance during rapid on-site evaluation (ROSE). The exercise aimed to assess the diagnostic adequacy and provide technical recommendations on each of the whole slide images from four fine-needle aspiration biopsy (FNAB) samples of the thyroid in a setting of ROSE. Methods: Four whole slide imaging cases, each comprising one Diff-Quik^TM stained preparation of an FNAB of the thyroid, were provided to all laboratories currently enrolled in the RCPAQAP Cytopathology diagnostic programmes. Each scanned image represented one slide from the first pass collected by a radiologist under ultrasound guidance. Participating laboratories were encouraged to distribute the exercise to individual staff members who attend ROSE procedures. A laboratory practice questionnaire was also conducted. Results: There were a total of 186 submissions received for the assessment across the four virtual cases provided. Although the assessment of on-site adequacy by participants showed high concordance across some of the cases, there was variation in the initial diagnostic evaluation and technical recommendation. Conclusions: ROSE has been adopted as a standard procedure in many laboratories worldwide. A peer comparison of participating laboratories in an EQA exercise has highlighted ROSE as susceptible to variation across standard operating procedures, the provision of diagnostic adequacy, diagnostic feedback to the attending clinician, and technical recommendation.

Point of care testing (POCT) haematology analysers, an EQA perspective

The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) provides proficiency testing for a diverse range of Haematology laboratory tests. In recent years, requests for external quality assurance (EQA) programs for Haematology Point of Care (PoC) instruments has increased.

A review of Clostridium difficile testing algorithms from the RCPAQAP EQA program

Background: The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) offers external quality assurance (EQA) for pathology laboratories in Australia and over 60 other countries.

Review of current incidents and risk calculations used in the Royal College of Australasian Pathologists Key Incident Management and Monitoring Systems - a system that could be used by all Australasian medical laboratories, and easily adapted to worldwide use.

IntroductionThe Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) Key Incident Monitoring and Management Systems (KIMMS) program has found that some existing Quality Indicators are too broad or not well defined. The risk matrix in use does not allow changes in incident Detection or Probability. In 2020, a review was performed: what issues should KIMMS include as Key Incidents and how could risk measurement be improved?Materials and methodsTwenty-seven networked and stand-alone laboratories enrolled in KIMMS during 2020 were surveyed on 45 current and new indicators of risk in the total testing process. They were asked which indicators they considered were significant in causing patient harm. Existing risk matrices in use by members of the KIMMS Advisory Committee laboratories were reviewed regarding their size or structure (3x3 or 5x5) and the descriptions of consequences and probability.ResultsThirteen participants indicated 21 indicators should be monitored, and the KIMMS Advisory committee added a further 13 (11 from the remaining 24 and 2 new). Of the five risk matrices reviewed, all consistently used a 5x5 matrix to estimate Consequences vs Probability of harm. The KIMMS advisory committee added a third parameter to the calculation of Risk, Detectability.ConclusionAll 34 pre- and post- indicators should be monitored, covering all aspects of the total testing cycle other than analytical. The risk measurement can be improved by introducing a 5x5 risk matrix to evaluate harm (consequences x probability) and then evaluating risk by adding detectability; risk equals harm x detectability.

A review of external quality assurance program performance PD-L1 for NSCLC

The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) are accredited against International Standard (ISO/IEC) 17043 Conformity assessment – General requirements for proficiency testing. In 2017, the RCPAQAP began collaborating with the United Kingdom National External Quality Assessment Services for Immunocytochemistry and In-Situ Hybridisation (UK NEQAS ICC and ISH) for technical proficiency testing in PD-L1 for non-small cell lung cancer (NSCLC). RCPAQAP laboratories participating in the program has increased steadily over the last few years to 43 in 2021; 2018–2020 results will show that RCPAQAP participant results are comparable with results from the total number of 153 UK NEQAS participants.

Challenges in antibody titration for ABO-incompatible renal transplantation.

Accurate and regular monitoring of anti-A and anti-B titres pre- and post-transplantation plays a crucial role in the clinical management of patients receiving ABO-incompatible renal transplants. There is no standardized protocol or an external quality assurance program (EQA) currently available for this testing in Australia. The aim of this study was to investigate the diversity of techniques, test platforms and reagents that were currently in use in various laboratories with the aim of developing an EQA. An online survey was sent to the participants enrolled with the Royal College of Pathologists of Australasia Quality Assurance Program (RCPAQAP) to assess their interest in participation in the pilot study. A total of 24 participants who expressed interest were sent the group O plasma, A1 , A2 and B cells to perform ABO titration using their own methods. Participants reported a wide range of titre results, from 8 to 1024 for the anti-A titre using A1 cells, from 2 to 128 for anti-A titre using A2 cells and from neat to 32 for anti-B titre using B cells. There was a wide variation in titre results between and within different technologies. These findings demonstrate the need for an ABO titration EQA. Development of a standard technique and participation in an EQA program should, over time, reduce variation and enable transferrable results across testing centres, which will assist in consistent clinical interpretation and better outcomes for patients.

Lack of standardisation in interpretation and reporting of autoantibody assays: a survey analysis of Australasian laboratories with focus on line immunoassays.

Autoantibody assays are reported in a variety of formats. Results only slightly above established cut-offs provide lower likelihood ratios; therefore, their clinical significance may be more uncertain, which is not readily communicated with dichotomous qualitative reporting. Line immunoassays (LIA) are a common method for detecting antibodies to extractable nuclear antigens (ENA) and myositis-associated antibodies. However, recommended positive cut-offs are contentious. We distributed a survey via e-mail to participants in the Royal College of Pathologists of Australasia Quality Assurance Program (RCPAQAP) Immunology modules and to a dedicated immunology mailing list in Australasia. Questions explored general viewpoints surrounding autoantibody reporting, as well as current laboratory practices, with particular focus on interpretation and reporting of the most commonly used ENA LIA manufactured by Euroimmun. There were 31 responders, representative of at least 17 unique laboratories across Australia (8 public, 5 private) and New Zealand (4 laboratories). Responses suggest that autoantibody reporting is not standardised; there was variation in general viewpoints and reporting practices, particularly regarding the interpretation of and positive cut-offs used for the Euroimmun ENA LIA, which were contrary to the manufacturer's guidelines in a majority of the responses. Interpretative qualitative reporting based on results from other investigations and the clinical history was a common theme. There is large variation in the reporting of autoantibody assays within Australasia, especially by LIA. A majority of respondents report the most commonly used ENA LIA contrary to manufacturer's guidelines; alternative positive cut-offs are commonly utilised. LIA reports should indicate the level of positivity to enhance their relevance in the clinical decision-making process.

Gamma-Glutamyl Transferase (GGT) Is the Leading External Quality Assurance Predictor of ISO15189 Compliance for Pathology Laboratories.

Pathology results are central to modern medical practice, informing diagnosis and patient management. To ensure high standards from pathology laboratories, regulators require compliance with international and local standards. In Australia, the monitoring and regulation of medical laboratories are achieved by conformance to ISO15189-National Pathology Accreditation Advisory Council standards, as assessed by the National Association of Testing Authorities (NATA), and an external quality assurance (EQA) assessment via the Royal College of Pathologists of Australasia Quality Assurance Program (RCPAQAP). While effective individually, integration of data collected by NATA and EQA testing promises advantages for the early detection of technical or management problems in the laboratory, and enhanced ongoing quality assessment. Random forest (RF) machine learning (ML) previously identified gamma-glutamyl transferase (GGT) as a leading predictor of NATA compliance condition reporting. In addition to further RF investigations, this study also deployed single decision trees and support vector machines (SVM) models that included creatinine, electrolytes and liver function test (LFT) EQA results. Across all analyses, GGT was consistently the top-ranked predictor variable, validating previous observations from Australian laboratories. SVM revealed broad patterns of predictive EQA marker interactions with NATA outcomes, and the distribution of GGT relative deviation suggested patterns by which to identify other strong EQA predictors of NATA outcomes. An integrated model of pathology quality assessment was successfully developed, via the prediction of NATA outcomes by EQA results. GGT consistently ranked as the best predictor variable, identified by combining recursive partitioning and SVM ML strategies.

Papanicolaou Staining and Processing Troubleshooting Exercise Using Digital Pathology: Peer Comparison in an External Quality Assurance Setting

Background: The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) offers a comprehensive range of External Quality Assurance programs for all disciplines of pathology and is committed to delivering programs to advance outcomes in patient care and promote excellence in laboratory diagnostic and technical proficiency. Proficiency testing in cytopreparatory techniques became available for formal enrolment in 2018. The 2019 technical program focused on the demonstration of a laboratory to troubleshoot problems encountered during staining and processing. The exercise provided a peer comparison of a laboratory’s ability to (1) identify the problem viewed from a digital image and (2) describe the troubleshooting steps to rectify the problem using assessment guidelines. Methods: Ten troubleshooting exercises including whole-slide z-stacked virtual images, a reference slide, and an online Result Entry questionnaire were provided. Common staining and processing problems were demonstrated in these exercises. Multiple-choice responses were made available to participants for each case with 1 response requiring submission. Participants were then allowed free text to describe how they would rectify the problem. Results: Of the 72 participants who participated, 62 participants (86%) achieved a satisfactory assessment, 6 participants (8%) received a borderline assessment, and 4 participants (6%) received an unsatisfactory assessment. The average mark obtained was 32.7 out of a total of 45 marks, which equates to a satisfactory assessment. The highest mark obtained for this survey was 42.5. Conclusions: Quality cytopathology preparatory techniques are integral to mitigating the risk of diagnostic error. The digital pathology platform allowed homogeneity of samples for all participants and appeared to be a satisfactory mode for demonstrating the technical problems to participants. Laboratories participating in this survey showed good performance in identifying processing and staining problems on virtual images and working through the troubleshooting steps. The exercise also identified a method for troubleshooting formalin vapour-affected slides using citrate buffer which may be useful for laboratories following in-house validation.

Influence of isotopically labeled internal standards on quantification of serum/plasma 17α-hydroxyprogesterone (17OHP) by liquid chromatography mass spectrometry.

Objectives Our recent survey of 44 mass spectrometry laboratories across 17 countries identified variation ininternal standard (IS) choice for the measurement ofserum/plasma 17α-hydroxyprogesterone (17OHP) by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The choice of IS may contribute to inter-method variations. This study evaluated the effect of two common isotopically labeled IS on the quantification of 17OHP by LC-MS/MS. Methods Three collaborating LC-MS/MS laboratories from Asia, Europe and Australia, who routinely measure serum 17OHP, compared two IS, (1) IsoSciences carbon-13 labeled 17OHP-[2,3,4-13C3], and (2) IsoSciences deuterated 17OHP-[2,2,4,6,6,21,21,21-2H]. This was performed as part of their routine patient runs using their respective laboratory standard operating procedure. Results The three laboratories measured 99, 89, 95 independent samples, respectively (up to 100nmol/L) using the 13C- and 2H-labeled IS. The slopes of the Passing-Bablok regression ranged 0.98-1.00 (all 95% confidence interval [CI] estimates included the line of identity), and intercept of<0.1nmol/L. Average percentage differences of-0.04% to-5.4% were observed between the two IS materials, which were less than the optimal bias specification of 7% determined by biological variation, indicating no clinically significant difference. The results of 12 Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) proficiency samples (1-40nmol/L) measured by the laboratories were all within the RCPAQAP analytical performance specifications for both IS. Conclusions Overall, the comparison between the results of 13C- and 2H-labeled IS for 17OHP showed good agreement, and show no clinically significant bias when incorporated into the LC-MS/MS methods employed in the collaborating laboratories.

Performance measures for Australian laboratories reporting cervical cytology 2009–2017: the impact of the national HPV vaccination program

The significant decrease in the incidence of cervical cancer in Australian women since the implementation of an organised approach to cervical screening through the National Cervical Screening Program (NSCP) can be largely attributed to high-quality cervical cytology reporting by Australian laboratories. Performance measures for Australian laboratories reporting cervical cytology are a well-established and an integral part of monitoring and maintaining this high standard by facilitating interlaboratory comparison of performance. This study summarises the aggregate data collected annually by Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) over the decade from 2009 until 30 November 2017, when the NCSP was revised and the cervical screening test replaced the Pap test as the primary mode of screening women for preinvasive disease. Overall, laboratories continued to perform to a high standard over this period. However, the introduction of a national school and GP based human papillomavirus (HPV) vaccination program in 2006 had a significant impact on the reporting of possible and definite high-grade abnormalities. In the renewed cervical screening program which commenced in December 2017 and which is based on HPV testing and reflex liquid-based cytology, new performance benchmarks will need to be developed when sufficient data have been collected.

A review of external quality assurance program performance in non-gynaecological cytology and Pd-L1 For NSCLC

The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) are accredited against International Standard (ISO/IEC) 17043 Conformity assessment – General requirements for proficiency testing. This standard requires evaluation and commentary of participant performance including variation between participants and comparisons between previous testing rounds. To implement these requirements for the Cytopathology non-gynaecological programs in 2019, methods from the Anatomical Pathology diagnostic programs were utilised. Methods for case selection, evaluation of participants and results from the first year will be discussed. In 2017, the RCPAQAP began collaborating with the United Kingdom National External Quality Assessment Services for Immunocytochemistry and In-situ hybridisation (UK NEQAS ICC and ISH) for PD-L1 for non small cell lung cancer (NSCLC) technical proficiency testing. In 2018 there were 22 RCPAQAP participants enrolled in this program and in 2019, enrolments increased to 40 participants. Results from 2018/19 will be discussed and comparisons with the broader UK NEQAS participants will be made. The RCPAQAP issued a PD-L1 for NSCLC interpretation pilot and results from this pilot will also be discussed along with other updates and developments for Anatomical Pathology and Cytopathology programs in 2020.

Quality testing in toxicology

Maintaining up-to-date toxicology External Quality Assurance (EQA) programs can prove challenging given the new and synthetic drugs which constantly arise. Toxicology labs need to invest in the latest technology not only to keep pace with new and variant drugs, but also with changes to artificial urines and adulterants designed to mask illegal drugs. The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) currently provides 3 toxicology programs designed to supplement quality toxicology testing for a range of applications (from large state of the art laboratories to onsite workplace testing). These programs also need to keep pace with updates and emerging trends (which can vary on state/regional basis) and the input of an expert committee is an essential component. Ethical issues can arise when contentious programs are explored, e.g., an EQA for pill testing. Sourcing otherwise illegal drugs and their variants is difficult. Interesting data can sometimes emerge when samples are re-used in surveys 1-2 years apart and ‘new’ drugs are reported. Challenging labs with artificial urines and adulterants has also proved to be useful. Demonstrating ‘fitness for purpose’ is another function of quality testing and some onsite screening devices still have room for improvement, particularly for oral fluid testing.

A review of 10 years of data from an external quality assurance program for antiphospholipid antibodies: no evidence for improved aCL and β2GPI assay standardization

Background: Anticardiolipin (aCL) and anti-β2-glycoprotein I (aβ2GPI) antibodies are important markers in the diagnosis of the antiphospholipid syndrome. Previous studies have shown significant variability in results obtained from different kits and manufacturers for these antibodies. In response to this lack of homogeneity, there have been international initiatives aimed at improving the reproducibility and standardization of these assays. To assess if these standardization initiatives have led to improved consistency in routine diagnostic laboratory reporting of these antibodies, we retrospectively reviewed 10 years of data from an External Quality Assurance (EQA) program. Methods: Data submitted by laboratories participating in the Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) antiphospholipid EQA program over a ten-year period (2009–2018) for IgG and IgM aCL and IgG aβ2GPI antibodies were reviewed. Changes in assay methodologies, consensus of results against the target set by RCPAQAP, and the number of laboratories reporting semi-quantitative results were assessed. Results: Methodologies used for the detection of aCL and aβ2GPI antibodies have changed considerably since 2009, with a steady trend towards non-ELISA based methodologies, such as chemiluminescence, fluorescence immunoassay and Luminex based techniques. Consensus in resulting (defined as ≥80% concordance in reporting “negative” or “positive” results for a sample) did not significantly change across the 10-year period for any test. There was a significant decrease in the proportion of laboratories reporting semi-qualitative results (i.e., low/medium/high positive) for IgG aCL (P=0.0036) and IgG aβ2GPI antibodies (P=0.007). No significant change was noted for IgM aCL antibodies (P>0.999). Conclusions: Despite concerted efforts by a number of international groups to improve the standardization of aCL and aβ2GPI antibodies assays, a review of data obtained over a 10-year period of EQA testing in diagnostic laboratories demonstrated that there is no evidence to support that these efforts have translated into improvements in the consistency of IgG/IgM aCL and IgG aβ2GPI antibody results.

The Challenges of Implementing a PD-L1 Proficiency Testing Program in Australia

Background. One important initiative that commenced at the Royal College of Pathologists of Australasia Quality Assurance Program (RCPAQAP) in 2017 was the collaboration with United Kingdom National External Quality Assessment Scheme (UK NEQAS) Immunocytochemistry (ICC) and In-Situ Hybridization (ISH) for the challenging implementation of a PD-L1 immunohistochemistry (IHC) proficiency testing program for non-small cell lung carcinoma (NSCLC). A RCPAQAP participant survey in 2016 showed that only eight laboratories were performing PD-L1 testing. The aim of the collaboration was to increase the sample size of the pilot program to provide meaningful results that could be reported back to RCPAQAP participants with appropriate recommendations. Other challenges of assessment included standardising the clinical cut-offs for positivity for each commercial assay, interpretation of laboratory developed tests (LDTs), using appropriate tissue to cover the critical interpretation points for each assay, interchangeability of clones and interpretation proficiency testing. Methods. The use of a ‘Gold Standard’ for each commercial assay was used as a baseline to compare participant results and tumour proportion score bin categories were implemented to harmonise interpretation across clones. Conclusions. The findings of the pre-pilot test suggest that the use of a clinically validated PD-L1 IHC assay performs better during assessment than adopting a laboratory developed test (LDT). The assessment committee also concluded that tonsil showed a better dynamic range of positivity than placenta. It was acknowledged that participants are limited by the platforms they have available and so it was suggested that validating an optimal method against the clinical assay and continual verification of the test may produce the expected result. The next big challenge is to extend proficiency testing from technical to interpretation. This is being implemented globally via the International Quality Network for Pathology (IQNPath) with participation through local External Quality Assurance programs, including RCPAQAP.