B19 Virus EQA Programme Final Report QAV (B19DNA14)

Transcription

1 B19 Virus 2014 EQA Programme Final Report QAV (B19DNA14) Prof. Hubert GM Niesters Scientific Expert on behalf of QCMD Report authorised by the QCMD Executive in July 2014 A UKAS accredited proficiency testing provider (no. 4385) Not to be reproduced or quoted without permission of QCMD. Any queries about this report should be addressed to the QCMD Neutral Office. Unit 5, Technology Terrace, Todd Campus, West of Scotland Science Park, Glasgow, G20 0XA, Scotland Tel: +44 (0) , Fax: +44 (0) , info@qcmd.org, Web:

2 1. Programme aims To assess the proficiency of laboratories in detection and quantitation of B19 virus DNA. Participants are encouraged to read the QCMD Participants' Manual, which can be downloaded from the QCMD website. Any queries about this report should be addressed to the QCMD Neutral Office 2. Programme details B19DNA14 Date of panel distribution Number of participants Number of countries Number of respondents Number of datasets submitted 31/03/ (97.0%) 139 Total number of participants that did not return results Number of participants that did not return results and gave no reason 4 (3.0%) 4 3. Panel composition : Sample content: Sample matrix: Sample conc.: Sample status: Sample type: Sample content Sample * matrix Consensus concentration IU/ml Copies/ml Sample status Sample type B19DNA14-05 B19 Virus Type 1 Plasma Frequently detected Core B19DNA14-01 B19 Virus Type 1 Plasma Frequently detected Core B19DNA14-03 B19 Virus Type 1 Plasma Frequently detected Core B19DNA14-08 B19 Virus Type 1 Plasma Frequently detected Core B19DNA14-07 B19 Virus Type 1 Plasma Frequently detected Core B19DNA14-02 B19 Virus Type 1 Plasma Frequently detected Core B19DNA14-06 B19 Virus Type 1 Plasma Detected Educational B19DNA14-04 B19 Virus Negative Plasma - - Negative Core content of the panel samples and, where applicable, the subtype or strain of the pathogen. material used as a matrix in preparation of the panel samples. consensus values calculated from all of the data returned by participants in the specified unit, once outliers had been removed. The values are not technology specific and should not be used by participants for method comparison or as a target for individual laboratory assessment. Consensus values are calculated from the results reported by participants in either IU/ml or Copies/ml independent of the technology used and should not be used by participants to determine conversion factors between IU/ml and Copies/ml for their individual assays. the sample status assigned to each panel sample. Please see Appendix A for more information. panel samples classified as core proficiency samples. Homogeneity & stability assessment criteria can be found in the current version of the QCMD Participant Manual. *Plasma: human plasma previously screened negative for B19 virus (DNA). Panel samples B19DNA14-01 and -03 were duplicate samples. 2 of 8

3 Percentage of datasets QCMD 2014 B19 Virus 4. Programme results 4.1. Quantitative performance on the paired samples Assays may differ in the relative quantitative values they report. QCMD assesses quantitative proficiency based on the difference reported between paired samples, which provides a measure of proficiency independent of assay bias % 90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% 94.8% 2.6% 1.3% 0.0% 1.3% 0 - < <1 1 - < Log 10 units from the median difference In this round of the EQA, a set of paired samples containing B19 virus was assessed. The median difference in reported concentration between samples B19DNA14-05 and -01 was Log10 (10.02 fold difference). Participants were expected to report to within 0.5 log10 of the median difference generated from all quantitative data in order to show acceptable proficiency Quantitative analysis of the EQA data and performance scores for all panel samples IU/ml A WHO international standard expressing the quantitative results in International Units (IU) is available for B19 virus. The primary reporting unit in this EQA programme was therefore IU/ml. Of the 77 quantitative datasets returned to QCMD, 51 (66.2%) reported results in IU/ml. Quantitative scores by technology type in comparison to the consensus mean concentration for each positive panel sample. Total Consensus All technologies Conventional Real time Log 10 virus In-house b Commercial c concentration n=51 Mean SD B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA PCR n=2 n=30 n=17 : Consensus Log10 virus concentration: the mean quantitative value and standard deviation value for each panel sample expressed in log10 units and calculated once outlying values had been removed. Total. All technologies: number of datasets awarded each score (0 to 3). refers to datasets where an upper or lower limit of detection was reported or no value was reported (these data were excluded from the scoring). SD refers to the Standard Deviation. A breakdown of the results for all datasets is also provided based on technology type. e LAMP n=1 TMA g n=1 b: Details not presented. c: Abbott Parvo B19 PCR Kit (n=4), Altona Diagnostics Real Star Parvovirus B19 PCR kit (n=8), Argene Biomerieux Parvovirus B19 R-gene (n=2), Nanogen Parvovirus B19 ELITe MGB kit (n=1), QIAGEN artus Parvo B19 PCR Kit (LC) (n=5), QIAGEN artus Parvo B19 PCR Kit (RG) (n=3), QIAGEN artus Parvo B19 PCR Kit (TM) (n=3), Roche Cobas TaqScreen DPX Test (n=3), Roche Lightcycler Parvovirus 19 Quantification Kit (n=1). e: Diasorin Liaison Iam (n=1). g: Grifols Polska Procleix Parvo/HAV Assay (n=1). 3 of 8

4 Quantitative scores by technology type in comparison to the technology consensus mean concentration per positive panel sample. Tech. Consensus Real time PCR Log 10 virus Commercial c concentration n=30 Mean SD B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA Tech. Consensus Log 10 virus concentration Real time PCR n=17 Mean SD B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA : Tech. Consensus Log10 virus concentration: the mean quantitative value and standard deviation value for each panel sample expressed in log10 units and calculated once outlying values had been removed. The number of datasets awarded each score (0 to 3) is then presented. refers to datasets where an upper or lower limit of detection was reported or no value was reported (these data were excluded from the scoring). SD refers to the Standard Deviation. c: Abbott Parvo B19 PCR Kit (n=4), Altona Diagnostics Real Star Parvovirus B19 PCR kit (n=8), Argene Biomerieux Parvovirus B19 R-gene (n=2), Nanogen Parvovirus B19 ELITe MGB kit (n=1), QIAGEN artus Parvo B19 PCR Kit (LC) (n=5), QIAGEN artus Parvo B19 PCR Kit (RG) (n=3), QIAGEN artus Parvo B19 PCR Kit (TM) (n=3), Roche Cobas TaqScreen DPX Test (n=3), Roche Lightcycler Parvovirus 19 Quantification Kit (n=1) Quantitative analysis of the EQA data and performance scores for all panel samples Copies/ml Of the 77 quantitative datasets returned to QCMD, 26 (33.8%) recorded results in copies/ml. Quantitative scores by technology type in comparison to the consensus mean concentration for each positive panel sample. Consensus Log 10 virus Total All technologies concentration n=26 Mean SD Commercial c n=13 n=13 B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA PCR Real time : Consensus Log10 virus concentration: the mean quantitative value and standard deviation value for each panel sample expressed in log10 units and calculated once outlying values had been removed. Total. All technologies: number of datasets awarded each score (0 to 3). refers to datasets where an upper or lower limit of detection was reported or no value was reported (these data were excluded from the scoring). SD refers to the Standard Deviation. A breakdown of the results for all datasets is also provided based on technology type. c: AmpliSens Parvo B19 PCR Kit (n=1), Argene Biomerieux Parvovirus B19 R-gene (n=3), Nanogen Parvovirus B19 ELITe MGB kit (n=5), PrimerDesign Real-time PCR B19 (n=1), QIAGEN artus Parvo B19 PCR Kit (TM) (n=1), Roche Lightcycler Parvovirus 19 Quantification Kit (n=2). 4 of 8

5 Percentage of datasets QCMD 2014 B19 Virus Quantitative scores by technology type in comparison to the technology consensus mean concentration per positive panel sample. Tech. Consensus Real time PCR Log 10 virus Commercial c concentration n=13 Mean SD B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA Tech. Consensus Log 10 virus concentration Real time PCR n=13 Mean SD B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA B19DNA : Tech. Consensus Log10 virus concentration: the mean quantitative value and standard deviation value for each panel sample expressed in log10 units and calculated once outlying values had been removed. The number of datasets awarded each score (0 to 3) is then presented. refers to datasets where an upper or lower limit of detection was reported or no value was reported (these data were excluded from the scoring). SD refers to the Standard Deviation. c: AmpliSens Parvo B19 PCR Kit (n=1), Argene Biomerieux Parvovirus B19 R-gene (n=3), Nanogen Parvovirus B19 ELITe MGB kit (n=5), PrimerDesign Real-time PCR B19 (n=1), QIAGEN artus Parvo B19 PCR Kit (TM) (n=1), Roche Lightcycler Parvovirus 19 Quantification Kit (n=2) Qualitative performance on the core proficiency samples 100.0% 90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% 96.4% 2.7% 0.9% 0.0% 0.0% 0.0% 0.0% 0.0% 7/7 6/7 5/7 4/7 3/7 2/7 1/7 0/7 Number of core samples correct The QCMD EQA panels contain a range of samples, designed to look at different aspects of assay performance. Panel members are designated core proficiency samples on the basis of scientific information, clinical relevance and clinical experience (published literature and professional clinical guidelines) and, where available and appropriate, established target performance limits taken from previous QCMD EQA distributions. Laboratories are expected to correctly analyse and report the core proficiency samples in order to show acceptable proficiency. 5 of 8

6 4.5. Qualitative analysis of the EQA data for all panel samples The number (percentage) of correct qualitative results is presented below. Qualitative data were returned by participants as 'positive', 'negative' or 'not determined'. Not determined results were counted as incorrect for all panel samples (positive or negative). QCMD organises datasets according to commercial and in-house technology groups, which are Conventional PCR, Real time PCR, NASBA, SDA, TMA and bdna. Where datasets were reported as other for a technology or kit method this was reviewed by the QCMD Neutral Office and assigned to an appropriate group where possible. Table i: Number of correct qualitative results per panel member and technology type Sample content Sample status n=111 n=8 n=51 Real time n % n % n % n % B19DNA14-05 B19 Virus Type 1 Frequently detected B19DNA14-01 B19 Virus Type 1 Frequently detected B19DNA14-03 B19 Virus Type 1 Frequently detected B19DNA14-08 B19 Virus Type 1 Frequently detected B19DNA14-07 B19 Virus Type 1 Frequently detected B19DNA14-02 B19 Virus Type 1 Frequently detected B19DNA14-06 B19 Virus Type 1 Detected B19DNA14-04 B19 Virus Negative Negative Total Conventional PCR datasets In-house b Commercial c n=52 Table ii: Qualitative performance scores per technology type Total PCR All technologies Conventional Real time Sample status In-house b Commercial c n=111 n=8 n=51 n=52 B19DNA14-05 Frequently detected B19DNA14-01 Frequently detected B19DNA14-03 Frequently detected B19DNA14-08 Frequently detected B19DNA14-07 Frequently detected B19DNA14-02 Frequently detected B19DNA14-06 Detected B19DNA14-04 Negative Key to Table i and ii : Sample content: content of the panel samples and, where applicable, the subtype or strain of the pathogen. Sample status: the sample status assigned to each panel sample. Please see Appendix A for more information. Total datasets: number and percentage of datasets reporting the correct qualitative result for each panel sample Total. All technologies: number of datasets awarded each score (0 to 3). A breakdown of the results for all datasets is also provided based on technology b: Details not presented. c: Abbott Parvo B19 PCR Kit (n=4), Altona Diagnostics Real Star Parvovirus B19 PCR kit (n=7), AmpliSens Parvo B19 PCR Kit (n=1), Argene Biomerieux Parvovirus B19 R-gene (n=4), Fast track diagnostics FTD mastermix (n=1), Fast-track diagnostics FTD Fever and rash (n=1), Fast-track diagnostics FTD Neuro 9 (n=1), Focus Diagnostics Parvovirus B19 Primer Pair (n=1), GFE Blut mbh Virus Screening PCR Kit (n=2), Nanogen Parvovirus B19 ELITe MGB kit (n=6), PrimerDesign B19 PrimerDesign Taqman (n=1), PrimerDesign Real-time PCR B19 (n=1), QIAGEN artus Parvo B19 PCR Kit (LC) (n=5), QIAGEN artus Parvo B19 PCR Kit (RG) (n=5), QIAGEN artus Parvo B19 PCR Kit (TM) (n=3), Roche Lightcycler Parvovirus 19 Quantification Kit (n=5), Sacace B19 Real-TM Quant (n=1), TIBMolbiol (n=1), TIBMolBiol Lightmix kit parvovirus B19 (n=1). 6 of 8

7 5. Comments The number of participants in the 2014 B19 Virus EQA programme was 132. This represents an increase of 9.1% on the 2013 B19 virus EQA programme (n=121). The majority of PCR datasets were generated using real time PCR assays (92.1%; n=128). Of the real time PCR datasets 65 (50.8%) were generated using commercial kits and 63 (49.2%) using in-house developed assays. Quantitative data were returned to QCMD in 77 (55.4%) datasets, this is a similar proportion to the 2013 EQA programme (56.9%). Quantitative analysis Quantitative paired sample analysis was performed on two B19 virus samples. Analysis showed that 73 (94.8%) quantitative datasets quantified the two samples to within 0.5Log10 from the median difference. A B19 virus WHO international standard expressed in International Units (IU) is available. Therefore, the primary reporting unit in this EQA programme was IU/ml. Of the 77 quantitative datasets received, 51 (66.2%) were reported using IU/ml and 26 datasets (33.8 %) were reported in Copies/ml. Quantitative analysis - IU/ml For participants reporting in IU/ml, standard deviation values for ranged from to log10 IU/ml. This SD range was lower than 2013 (0.423 to 0.795). Quantitative analysis - Copies/ml For participants reporting in copies/ml, standard deviation values ranged from to log10 copies/ml. This standard deviation value range was higher than 2013 (0.406 to 0.536). Qualitative analysis One hundred and seven (96.4%) datasets returned by participants reported all core samples correctly. This was similar to the 92.6% of datasets that correctly reported all core samples in One false positive result was reported on the true negative panel sample (B19DNA14-04) resulting in a false positivity rate of 0.9%. This compares to 1.0% (n=1) false positivity on the true negative panel sample in in the 2013 EQA programme. 7 of 8

8 Appendix A Calculation of the consensus and technology concentrations In order to compare participants results within specific technologies or kit methods, where sufficient datasets were reported (5 or more) methods or kits were assigned to a technology group e.g. Real time PCR, bdna or NASBA etc. Where datasets were reported as 'other' for a technology or kit method this was reviewed by the QCMD Neutral Office and assigned to an appropriate group where possible. The negative panel samples were not included in these analyses. An assigned value was calculated for each panel sample using two methods. These were: 1. Consensus concentration - the mean of the participants' results once outliers had been removed. 2. Technology consensus concentration - the mean of the participants' results per technology group once outliers had been removed. The standard deviation was calculated as the square root of the mean square for error from the ANOVA table where the response was the log concentration of participants results with outliers removed. The factor was technology group. Outliers were defined as values with a standardised residual with modulus greater than three. Although outliers were removed for the calculation of the assigned values they were included in the data analysis. Scores were awarded based on the distance from the calculated mean value for each panel sample. Zero points was awarded if the quantitative value returned was within one standard deviation from the mean. One point was awarded if the quantitative value was between one and two standard deviations, two points if the value was within two and three standard deviations and three points for quantitative values more than three standard deviations from the mean. Further information about the QCMD method of analysing EQA data can be found in the following peer-reviewed publication: Staines HJ, Garcia-Fernandez L, Pogothata R, Wallace PS, MacKay WG, van Loon AM. Monitoring performance of nucleic acid-based diagnostic measurement system users by EQA. Accred Qual Assur. 2009; 14: Assigning the sample status Sample status is assigned by peer-group consensus, based on the qualitative results returned by all participants. It is not a measure of the 'strength' of a positive sample nor is it technology-dependent, and is used solely for the scoring of the EQA data. The rationale for the sample status is: Frequently detected: Detected: Infrequently detected: Negative: More than 95% of datasets recorded the correct positive result. Between 65% and 95% of datasets recorded the correct positive result. Less than 65% of datasets recorded the correct positive result. A panel sample that does not contain the target and produces an unequivocal negative result. Scoring system for qualitative EQA data The scores awarded for qualitative EQA data were based on the sample status. The scoring system is represented in the following table, where 0 is 'highly satisfactory' and 3 is 'highly unsatisfactory'. Colour has been included as an extra visual aid. Scoring system based on the assigned sample status Sample status Participant's result Negative Not determined Positive Frequently detected Detected Infrequently detected Negative QCMD The QCMD EQA programme samples, associated reports and data generated during this programme are intended for External Quality Assessment (EQA) and Proficiency Testing (PT) purposes only. QCMD operates according to a strict Code of Practice which is in line with ISO/IEC and associated standards. Data reported in QCMD programmes is representative of a laboratory s standard diagnostic testing protocols irrespective of the technology they use. The data provided in the reports are based on technical information provided by the individual laboratories as part of the assessment process, as such it does not constitute a formal technology method comparison. All text and images produced by QCMD are the property of QCMD unless otherwise stated. The reproduction and use of these materials is not permitted without the express written consent of QCMD. The use of the information provided in QCMD reports for commercial purposes is strictly prohibited. 8 of 8