Purpose: The analytical performance of the cobas 6800 HIV-1, HBV and HCV assays was verified and evaluated to the COBAS Ampliprep/COBAS TaqMan assays.
Methodology: The precision, limit of detection (LoD), limit of quantification (LoQ) and linearity were verified using pooled residual clinical samples. The analytical specificity was verified with negative plasma. HIV-1 analytical reactivity was verified with WHO reference preparations. Accuracy was verified using EQA plasma panels. Evaluation of the equipment was performed using prospectively collected clinical whole blood samples.
Results: Excellent precision was demonstrated using both testing protocols (coefficient of variation ≤15 %). The LoDs using the 500 and 200 µl protocols were 20 and 50 cp ml-1 for HIV-1, 10 and 20 IU ml-1 for HBV and 15 and 40 IU ml-1 for HCV, respectively. The LoQs were 40 and 100 cp ml-1 for HIV-1, 20 and 25 IU ml-1 for HBV and 30 and 80 IU ml-1 for HCV, respectively. Assays demonstrated good linearity (R2 ≥0.96). The analytical specificity of the assays was 100 %. There was excellent agreement between the cobas 6800 and CAP/CTM assays (kappa>0.94). The sensitivity, specificity, positive predictive value and negative predictive value for each of the assays were ≥99 %. The cobas HIV-1 and HCV mean quantifications were 0.03 log10 cp ml-1 and 0.17 log10 IU ml-1 higher than the CAP/CTM. The cobas HBV mean quantification was 0.17 log10 IU ml-1 lower than the CAP/CTM. Subtype/genotype specific differences were not observed.
Conclusion: Cobas 6800 equipment and assays demonstrated excellent performance and correlated well with CAP/CTM assay results.
Keywords: COBAS Ampliprep/COBAS TaqMan; Cobas 6800; HBV; HCV; HIV; viral load.