Multicenter comparison of the new Cobas 6800 system with Cobas Ampliprep/Cobas TaqMan and Abbott RealTime for the quantification of HIV, HBV and HCV viral load

Background: The new Roche Cobas 6800 platform (C6800) has been recently introduced for viral load (VL) measurement.

Objectives: Comparing C6800 to Cobas Ampliprep/Cobas TaqMan v2.0 (CAP/CTM) for the quantification of HIV, HBV and HCV viremia, and to the Abbott RealTime assay (ABB) for HCV quantification.

Study design: We analysed 121 samples for HBV, and 139 for HIV-1 including 2 groupO and 137 group M viruses (36.5% subtype B, 27.0% CRF02_AG, 22.6% from other clades, and 14% subtype not available). For the 100 HCV samples compared with CAP/CTM, 42% were genotype 1 and 17% were genotype 4. For the 68 HCV samples compared with ABB, 52.9% were genotype 1 and 22.1% were genotype 4.

Results: C6800 results correlated well with those of CAP/CTM for all three viruses (R²: 0.97-0.99). However, C6800 can yield different viraemia results: higher for HIV (mean difference: +0.11 log₁₀copies/mL, p<0.0001), and lower for HBV (mean difference:-0.11 log₁₀ IU/mL, p<0.0001). Differences exceeded 0.5 log₁₀ for 6.5% of HIV-1 samples and 7.4% of HBV samples. For HCV quantification, C6800 gave mostly lower values than the other assays towards the bottom of the range, and higher values in the upper part of the range, especially in comparisons with ABB, for which 28% of differences exceeded 0.5 log₁₀ IU/mL. No particular HCV genotype was identified as responsible for these differences.

Conclusion: Overall, the comparison tests between C6800 and CAP/CTM systems are satisfactory for the three viruses. Frequent discrepancies were observed between C6800 and ABB for HCV.