FINAL REPORT HBV Serology External Quality Assessment Scheme

Transcription

1 FINAL REPORT HBV Serology External Quality Assessment Scheme Programme codes: HBVC4310, HBVC435 Panel ID: 2008/Mar/11 HBV Serology EQAS Panel ID 2008/Mar/11 Page 1 of 9

2 The NRL is a: NATA-accredited proficiency testing provider, complying with ILAC-G13:2000 WHO Collaborating Centre on HIV/DS Report prepared by Wayne Dimech and distributed in the week beginning 2008/Mar/31 National Serology Reference Laboratory, Australia (NRL) 4 th Floor, Healy Building, 41 Victoria Parade, Fitzroy, Victoria 3065 Australia HBV Serology EQAS Panel ID 2008/Mar/11 Page 2 of 9

3 1 INTRODUCTION The National Serology Reference Laboratory, Australia (NRL) distributes three Hepatitis B Virus (HBV) Serology External Quality Assessment Scheme (EQAS) panels each year to participants that conduct HBV serology testing. The NRL manages its EQAS using the DigitalPT informatics system (DigitalPT) developed and operated by HealthMetrx Canada Inc. (HMX). AcroMetrix Corporation and its subsidiaries (AcroMetrix) provide logistical support for participants enrolled through AcroMetrix. All participants in the NRL s EQAS are provided with a unique and confidential identifier. This identifier is known only by participants, NRL, HMX and AcroMetrix. This report presents and discusses the results reported for HBV Serology EQAS Panel ID 2008/Mar/11. The aim of this panel was to examine the integrity of result reporting. 1.1 Copyright The information and data included in this report are the intellectual property of the NRL, a division of St Vincent s Institute. They may not be reproduced, in whole or in part, for any purpose without the written permission of the NRL; nor may they be used in any type of advertising or sales promotion. 2 METHODS 2.1 Panel ID composition, preparation and distribution The HBV Serology EQAS panel for programme code HBVC4310 consisted of ten plasma samples. The HBV Serology EQAS panel for programme code HBVC435 consisted of five samples which were the same as the first five samples included in the panel for programme code HBVC4310. The reactivity to Hepatitis B surface antigen (HBsAg), total antibody to Hepatitis B core antigen (anti-hbct), antibody to HBsAg (anti-hbs), Hepatitis B e antigen (HBeAg) and antibody to HBeAg (anti-hbe) of each sample is detailed in Table A1. The samples were obtained from blood donors from Australia, Southeast Asia and the Western Pacific region. Each pooled sample was prepared by mixing equal volumes of at least two samples that were from the same country of origin and that had similar antibody and antigen profiles. The samples were tested by the NRL in a range of assays to confirm their reactivity (Table A1). The samples were aliquotted and their homogeneity was confirmed by testing conducted at the NRL. Representative samples were tested by the NRL following shipment to participants to confirm their stability. HBV Serology EQAS Panel ID 2008/Mar/11 was distributed to 110 participants in 31 countries. Participant NRL0150 was not sent a panel because the participant had notified the NRL prior to the distribution of panels that it had temporarily ceased HTLV testing and would not be able to test the panel. HBV Serology EQAS Panel ID 2008/Mar/11 Page 3 of 9

4 2.2 Evaluation of results Reference results were not available for IgM antibody to Hepatitis B core antigen (anti-hbcigm). Consequently, assay interpretations reported for anti-hbcigm assays were not evaluated Qualitative evaluation Where appropriate, results reported by participants for assay interpretations were compared with the relevant reference results (Table A1). In instances where an assay interpretation was not provided for a sample tested in a rapid or agglutination assay, the reactivity for the sample that was reported by the participant was taken to also be the assay interpretation. An aberrant assay interpretation is one that did not agree with the relevant reference result Statistical analyses Tukey s Outlier Filter was used to identify outlying results. An outlying test result is a numerical test result that is found to be statistically different from other test results reported by participants that tested the same sample in the same assay. Occasionally the EQAS coordinator may manually flag a result as outlying, which will cause it to be removed from the statistical analysis. This will only occur when inclusion of the result will erroneously bias the statistical analysis e.g. when the result is from the testing of an incorrect sample. 3 RESULTS s from 93 participants were received for HBV Serology EQAS Panel ID 2008/Mar/11. s were not received by the closing date for the acceptance of results from Participants NRL0016, NRL0100, NRL0108, NRL0276, NRL0346, NRL0347, NRL0348, NRL0351, NRL0352, NRL0353, NRL0354, NRL0355, NRL0356, NRL0485, NRL0525 and NRL0578. Participant NRL0276 contacted the NRL after panels had been distributed and indicated that it was not able to test the panel because it had temporarily ceased testing for HIV. Participants NRL0255 and NRL0317 used kits that had expired. All participants that reported outlying test results, aberrant assay interpretations or results that warranted comment are listed in Table 1. Each participant is advised to check Table 1 and to review Section 4 (DISCUSSION), which comments on other results that may need review. HBV Serology EQAS Panel ID 2008/Mar/11 Page 4 of 9

5 Table 1. Participants that reported outlying test results, aberrant assay interpretations or results that warranted comment Laboratory ID* Sample ID Reference Assay Outlying s** NRL0001 C Negative Abbott PRISM HBsAg ChLIA Type of Identified Aberrant Assay Interpretations*** Abbott AxSYM HBsAg Version 2 MEIA NRL0008 G Negative Abbott AxSYM HBsAg Confirmatory Assay/Abbott AxSYM HBsAg Version 2 MEIA NRL0010 J Reactive Abbott AxSYM CORE MEIA NRL0013 G, I Negative Abbott Murex HBsAg Version 3 EIA NRL0026 D Reactive Abbott ARCHITECT Anti-HBc CMIA NRL0030 D Reactive Abbott ARCHITECT Anti-HBc CMIA NRL0070 NRL0118 A, C, F, G, I Negative B, D, E, H, J Reactive Miscellaneous Comments Abbott AxSYM CORE MEIA C Negative I Abbott PRISM HBsAg ChLIA B Reactive H NRL0119 F Negative Abbott ARCHITECT Anti-HBc CMIA NRL0166 H Positive Ortho Vitros HBsAg Confirmatory/Ortho Vitros HBsAg Assay NRL0235 F Reactive Abbott AxSYM AUSAB MEIA J Reactive Abbott AxSYM HBsAg Version 2 MEIA NRL0255 A-J Bio-Rad MONOLISA HBsAg ULTRA EIA HBV Serology EQAS Panel ID 2008/Mar/11 Page 5 of 9

6 Table 1. Participants that reported outlying test results, aberrant assay interpretations or results that warranted comment (continued) Laboratory ID* Sample ID Reference Assay Outlying s** NRL0290 F Negative Abbott PRISM HBsAg ChLIA Type of Identified Aberrant Assay Interpretations*** Miscellaneous Comments NRL0312 A Negative Abbott Murex HBsAg Version 3 EIA NRL0314 F Negative Abbott AxSYM HBsAg Version 2 MEIA NRL0323 C, I Negative DiaSorin ETI-MAK-4 HBsAg EIA NRL0370 NRL0442 C, F, G, I Negative Dade Behring Enzygnost HBsAg 5.0 EIA I Negative Orchid Biomedical Virucheck HBsAg (Dipstick) E Reactive Dade Behring Enzygnost HBsAg 5.0 EIA G Negative NRL0477 I Negative Abbott IMx HBsAg Version 2 MEIA NRL0481 C, F, G, I Negative Abbott Murex HBsAg Version 3 EIA B, D, H, J Reactive Note: * Identification. ** An outlying test result is a numerical test result that is found to be statistically different from the other test results reported by participants that tested the same sample in the same assay. *** An aberrant assay interpretation is one that did not agree with the relevant reference result. HBV Serology EQAS Panel ID 2008/Mar/11 Page 6 of 9

7 4 DISCUSSION Overall, ten participants each reported at least one HBsAg assay interpretation that was considered to be aberrant. No participant reported an aberrant assay interpretation for anti-hbct, anti-hbe, HBeAg or anti-hbs assays. Participant NRL0013 reported HBsAg reactivity for negative samples G and H with the Sample to cut-off ratio (S:Co) being just above the cut-off (1.4 and 1.36). A neutralisation test performed on all reactive samples correctly identified samples G and H as negative. The anti-hbct results for all of the samples A-J reported by Participant NRL0070 were identified as outlying. In fact, Participant NRL0070 s results were consistently different to those reported by the other 11 users of this assay; i.e. when all participants (other than Participant NRL0070), reported a S:Co result of greater than 1.0, Participant NRL0070 reported a S:Co less than 1.0. However, the assay interpretations for all samples reported by Participant NRL0070 were concordant with the reference results. Participant NRL0070 reported HBsAb and HBsAg results from the Abbott ARCHITECT assays. It is likely that Participant NRL0070 incorrectly chose the Abbott AxSYM CORE MEIA when entering their anti-hbct results into DigitalPT. The Abbott AxSYM CORE MEIA is a competitive inhibition assay in which reactive test results give a S:Co less than 1.0, whereas the Abbott ARCHITECT is a sandwich chemiluminescent assay with reactive test results giving S:Co ratios greater than 1.0. s from four samples tested on the Abbott PRISM HBsAg ChLIA and reported by Participant NRL0118 were identified as aberrant and/or outlying. Participant NRL0118 reported an aberrant assay interpretation for the HBsAg positive sample B. All fourteen of the other participants using the Abbott PRISM HBsAg ChLIA reported Sample B as reactive. Participant NRL0118 reported an aberrant assay interpretation for the HBsAg negative sample I. In the first test run, a low reactive result for the sample (S:Co 3.86) was obtained. On retesting in duplicate, both results were again reactive at even higher levels (S:Co and ). The average S:Co for sample I reported by other participants using this assay was Participant NRL0118 reported a reactive result for the HBsAg negative sample C in the first test run (S:Co ), which was identified as outlying. An instrument error that occurred in the second test run prevented Participant NRL0118 from reporting an assay interpretation for this sample. Participant NRL0118 reported three reactive results from two test runs for the HBsAg positive sample H (S:Co 1,010.74, 3.43 and 3.91), all of which were identified as outlying. The mean S:Co for sample H reported by other participants using this assay was Participant NRL0118 correctly reported the assay interpretation for sample H as reactive. Participant NRL0118 did not submit any results for HBsAg neutralisation. Participant NRL0118 reported unusual and erratic results for samples C, H and I that should be investigated. Possible causes of these results may be inappropriate sample handling or instrument malfunction. Participant NRL0255 incorrectly reported test results for Event 3, s for all samples were changed by the administrator to Laboratory error and none of the test results were evaluated. The EQAS panels supplied are clearly marked with the programme code and the shipment identification. Participant NRL0312 reported an aberrant assay interpretation for the negative sample A in the Abbott Murex HBsAg Version 3 EIA. Participant NRL0312 screened all samples using the Bio-Rad MONOLISA HBsAg ULTRA EIA and re-tested reactive samples on the Abbott Murex HBsAg Version 3 EIA and the Abbott Determine HBsAg Immunoassay. Although samples B, D, E, H and J were reactive on the Bio-Rad MONOLISA HBsAg ULTRA EIA, and re-tested on the Abbott Determine assay, Participant NRL0312 indicated that samples A, D, E, H and J were re-tested on the Abbott Murex HBsAg Version 3 EIA. Participant NRL0312 may have incorrectly entered the HBV Serology EQAS Panel ID 2008/Mar/11 Page 7 of 9

8 Abbott Murex HBsAg Version 3 EIA results for sample B as being for sample A. It is suggested that, once entered into DigitalPT, the results are printed using the facility provided by DigitalPT and checked for accuracy. s can be edited up until the closing date. Participant NRL0312 did not report neutralisation test results for reactive samples. Participant NRL0370, using the Dade Behring Enzygnost HBsAg 5.0 EIA, reported assay interpretations for four of the five HBsAg negative samples (samples C, F, G and I) as reactive or inconclusive, all of which were identified as aberrant. results for the fifth HBsAg negative sample (sample A) showed S:Co values of 0.90, 0.94 and These results suggest that sample carry-over may be occurring. The NRL recommends that Participant NRL0370 investigate the possible causes of these results, including the functioning of the EIA processor that is in use. Participant NRL0370 also tested all samples using the Orchid Biomedical Virucheck HBsAg (Dipstick) and reported an aberrant assay interpretation for the HBsAg negative sample I. Participant NRL0370 was the only laboratory to use the Orchid Biomedical Virucheck HBsAg, so it was not possible to determine whether this aberrant result was due to the laboratory s processes or the assay giving a false positive result in this sample. No HBsAg neutralisation test results were submitted by this participant. Participant NRL0442 also used the Dade Behring Enzygnost HBsAg 5.0 EIA and reported two aberrant HBsAg assay interpretations for samples E (false negative) and G (false reactive). This participant also reported a Laboratory error for sample A and an Instrument aspiration error for sample H. These aberrant results may have been due to sample mix-up. Eight of the ten Abbott Murex HBsAg Version 3 EIA test results reported by Participant NRL0481 were identified as outlying. All HBsAg assay interpretations reported were concordant with the reference results. All reactive test results were reported by this participant as having a S:Co ratio of 3.00, whereas the means of the S:Co ratios reported for the positive samples by other participants using the same assay were close to 30. This error may have been due to a misinterpretation of the data entry requirements for DigitalPT. Participants may enter the optical density and the cut-off, the S:Co value or all three. If the result is above or below the linear/detection limit, the signs > or < can precede the result. Detailed instructions are available from DigitalPT website or from the NRL. Many of the participants that reported falsely reactive HBsAg test results did not report HBsAg neutralisation test results. It is strongly suggested that all samples with reactive HBsAg test results be confirmed using a well-chosen neutralisation assay. Acknowledgements The NRL thanks our colleagues who supply samples for the EQAS. We thank all our participants for their cooperation. Comments or queries about this report, or about any problems you might experience with HBV serology testing, will be welcomed by Kathy Smeh on or via on kathy@nrl.gov.au. HBV Serology EQAS Panel ID 2008/Mar/11 Page 8 of 9

9 5 APPENDIX Table A1. Characterisation of the samples that comprised HBV Serology EQAS Panel ID 2008/Mar/11 Sample Identification by Programme Sample Origin Sample Type Abbott Murex HBsAg Version 3 MEIA Abbott Murex HBsAg Confirmatory Version 3 biomérieux VIDAS HBeAg/Anti-HBe ELFA Abbott AxSYM AUSAB MEIA Abbott AxSYM CORE MEIA HBVC4310 HBVC435 (S/Co ) % Reduction (IV*) HBeAg (IV ) Anti-HBe (miu/ml ) (S/Co ) A A Australian blood donors Pooled plasma 0.50 Negative Not tested Not applicable 0.00 Negative 0.72 Negative 0.00 Negative 1.70 Negative B B Western Pacific blood donors Pooled plasma Reactive 93.0 Positive 5.31 Reactive Negative 0.00 Negative 0.05 Reactive C C Australian blood donors Pooled plasma 0.53 Negative Not tested Not applicable 0.00 Negative 0.74 Negative Reactive 1.37 Negative D D Southeast Asian blood donors Pooled plasma Reactive 99.0 Positive 0.00 Negative 0.00 Reactive 0.00 Negative 0.07 Reactive E E Southeast Asian blood donors Pooled plasma Reactive 98.0 Positive 0.00 Negative 0.01 Reactive 0.00 Negative 0.04 Reactive F Australian blood donors Pooled plasma 0.58 Negative Not tested Not applicable 0.00 Negative 0.80 Negative Reactive 1.74 Negative G Australian blood donors Pooled plasma 0.52 Negative Not tested Not applicable 0.00 Negative 0.75 Negative 0.00 Negative 1.65 Negative H Not applicable Western Pacific blood donors Pooled plasma Reactive 82.0 Positive 5.31 Reactive 9.84 Negative 0.00 Negative 0.04 Reactive I Western Pacific blood donors Pooled plasma 0.57 Negative Not tested Not applicable 0.00 Negative 0.95 Negative Reactive 1.59 Negative J Australian blood donors Pooled plasma Reactive 98.0 Positive 0.00 Negative 0.00 Reactive 0.00 Negative 0.03 Reactive Note: Sample to cut-off ratio, where 1 is reactive HBsAg Hepatitis B surface antigen Assay interpretation miu/ml (milli-international Units per millilitre), where >10 is reactive HBeAg Hepatitis B e antigen Sample to cut-off ratio, where is reactive Anti-HBe Antibody to Hepatitis B e antigen * Index value, where >0.1 is positive for HBeAg Index value, where <0.4 is positive for anti-hbe HBV Serology EQAS Panel ID 2008/Mar/11 Page 9 of 9