Reproducibility of Roche cobas HIV-1, HBV and HCV real-time PCR assays on cobas 4800 in comparison with COBAS AmpliPrep/COBAS TaqMan assay equivalents

Background: Quantitative real-time PCR for viral load testing is vital for the diagnosis, disease monitoring and management of important blood-borne viral infections. Laboratories needing to switch to a newer real-time PCR system in favour of technological advancements require an evaluation on the reproducibility of its tests compared to the established, currently in-use system before their implementation as replacement viral load tests. In this study, we determine the reproducibility of the Roche cobas HIV-1, HBV and HCV real-time PCR tests on the newer cobas 4800 system when compared to the COBAS HIV-1, HBV and HCV (version 2.0) tests on the COBAS AmpliPrep/COBAS TaqMan system. Methods and materials: Twenty-one undiluted EDTA-plasma samples were selected for each assay pair by convenience sampling from known positive clinical specimens for this evaluation study. The procedures for nucleic acid extraction and real-time quantitative PCR were performed according to the manufacturer's instructions. Reproducibility was determined by measuring correlation using regression analysis and agreement using Bland-Altman analysis of only valid titer pairs that were within the linear ranges of each assay. IBM SPSS Statistics software version 21 was used for both analyses. Results: The number of samples that were out of the linear range and were excluded from the analysis was 4, 5 and 1 sample for HIV-1, HBV and HCV tests, respectively. Cobas 4800 HIV-1, HBV and HCV tests demonstrated a good correlation with COBAS AmpliPrep/COBAS TaqMan HIV-1, HBV and HCV (version 2.0) tests with regression values of 0.9924, 0.9795 and 0.9284, respectively. All sample data recorded for all three assay pairs were found to be within the significant range of ± 1.96 SD. Conclusion: The performance of the cobas 4800 HIV-1, HBV and HCV tests were reproducible when tested with the COBAS AmpliPrep/COBAS TaqMan HIV-1, HBV and HCV version 2.0 tests, within each of the respective test's linear ranges. The cobas HIV-1, HBV and HCV real-time quantitative PCR tests on the cobas 4800 system are suitable as replacement viral load tests in our setting with acceptable performance compared to the currently in-use system.