Comparison of the COBAS Taqman PCR and b-DNA PCR in patients treated for hepatitis C genotype 1, partly co-infected with HIV
Abstract number: O182
Arends J.E., Boland G.J., Hoepelman I.M.
Background/Aim: Treatment decisions (e.g. discontinuation or shortening of therapy) are based on plasma hepatitis C (HVC) RNA measurements. Both quantitative and qualitative detection systems are commercially available. These systems rely either on target (Roche Cobas Taqman RT-PCR) or signal amplification (Bayer Versant b-DNA V3). Differences in linear amplification, sensitivity and specificity, lower limit of detection and standard of automated testing makes comparison between these assays mandatory. The aim of this study is to correlate plasma HCV RNA values of both the COBAS Taqman PCR and the Versant b-DNA PCR assay.
Methods: From 20 HCV genotype 1 positive patients treated with peginterferon alfa-2a and weight-based ribavirin, plasma samples at baseline, day 2 and at weeks 1, 2, 4, 8, 12, 48 of treatment and 24 weeks after therapy are collected for measurements of plasma HCV-RNA loads. Totally, paired samples with a quantitative range from undetectable to 1.6 10E7 IU/mL are compared, excluding those values that were undetectable. For both the COBAS Taqman (lower limit of detection 10 IU/mL) and the Versant b-DNA (lower limit of detection 615 IU/ml) 50 uL of plasma is used.
Results: A total of 86 paired samples are analysed with a median value for the Taqman assay of 5.05 log IU/mL versus a median value of 4.93 log IU/mL for the Versant b-DNA assay. In 69% of the measurements the Taqman PCR shows a higher HCV viral load than the b-DNA PCR. This is mainly for measurements in the higher viral loads, i.e. above 5log10 IU/mL. There is an excellent correlation between both assays (Spearman ranks coefficient 0.902, p < 0.01). A Bland-Altman analysis, shows a bias of 0.23 log10 IU/mL with a standard deviation of 0.45 (95% CI of -0.66 to 1.12 log10 IU/mL).
Conclusion: There is an excellent correlation between the COBAS Taqman and the Versant b-DNA assay. Overall, compared to the bDNA assay, the COBAS Taqman PCR measurements are higher, mainly within the higher viral loads.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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