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  • Beckman Coulter s DxN VERIS Molecular

    2021-09-27

    Beckman Coulter’s DxN VERIS Molecular Diagnostics System (DxN VERIS System) is a fully automated system for the quantitative analysis of molecular targets, integrating sample introduction, nucleic phosphodiesterase inhibitors extraction, reaction set-up, real-time PCR amplification and detection using TaqMan® chemistry, and results interpretation. The VERIS HBV Assay is a DNA-based quantitative nucleic acid amplification based assay for HBV, calibrated to the 3rd WHO International Standard for HBV (NIBSC 10/164). The objective of this study was to compare the HBV VLs obtained with the VERIS HBV Assay (Veris) to those obtained with the Roche COBAS TaqMan HBV Test, v2.0 (Cobas), Abbott RealTime HBV Assay (RealTime), Siemens VERSANT HBV DNA 1.0 Assay (Versant), Qiagen artus HBV RG PCR Kit (artus).
    Study design
    Results
    Discussion We have compared the HBV VL obtained with Veris to four currently marketed molecular assays. Bias was consistent and negative across the range for Veris compared to all four assays. Bias at the relevant clinical levels of 2000 and 20,000IU/mL ranged from −0.21 to −0.44 log10IU/mL and −0.16 to −0.49 log10IU/mL, respectively, depending on comparator. The QCMD HBV Panel results show Cobas reading higher than expected and Veris lower than expected for HBV genotype D and less so A, the most prevalent genotypes in Europe [1], [2], [3]. These results indicate that bias around −0.5 log10IU/mL may be expected when comparing these two assay methods, so our results are not surprising. The negative bias seen could affect decisions regarding treatment start, as current guidelines for immune-active phase of chronic HBV recommend treatment for HBeAg negative HBV patients with VL above 2000IU/mL and for HBeAg positive HBV patients with VL above 20,000IU/mL [1], [2]. Treatment decisions however are based on multiple factors, including ALT levels, histological liver disease, age, family history, and previous treatment history in addition to the VL levels [1], [2]. The use of multiple factors lessens the impact the negative bias seen with Veris would have on treatment decisions. Bias by site was consistent when compared to the combined data except at London where bias versus Cobas was −0.72 log10IU/mL across the range. Analysis of the combined site Cobas results without the London data revealed an average bias of −0.39 log10IU/mL (95% CI −0.47 to −0.32 log10IU/mL), consistent across the assay range (data not shown). Further investigation into London results included separate analyses for prospectively collected samples and retrospectively collected frozen samples. Results were similar for both. Investigations of sample handling techniques prior to testing were inconclusive, revealing no differences for Veris versus Cobas testing. A separate set of clinical samples (N=31) was provided to London by Beckman Coulter and tested with both Veris and Cobas on same day after similar thawing procedures. The results revealed an average bias (−0.38 log10IU/mL) similar to Nuclear lamina found at other Cobas comparison sites (data not shown). The percentage of samples differing by >0.5 log10 and >1.0 log10 in our study ranged from 37.2–52.2% and 9.3–19.4%, respectively, depending on comparison assay. Discordance of HBV assays and percentage of samples differing by >0.5 and >1.0 log10 have been shown to be higher when comparing results with values less than 3 log10, which may in part be related to different assay LODs or the variability of results at these levels [18], [19]. Our results are higher than seen phosphodiesterase inhibitors in other assay comparison studies, where 19–27% and 3.0–8.6% differing by >0.5 log10 and >1 log10, respectively, have been seen [18], [19], [20], [21]. A few studies, however, have seen up to 48% and 22% [19], [22], especially with majority of results below <3 log10[22]. For sample results differing by >1.0 log10 in our study, the percent below 3 log10 was 78.7% for Veris and Cobas, 53.1% for Veris and RealTime, 87.5% for Veris and Versant and 81.8% for Veris and artus.