Performance Evaluation of the Roche Cobas 5800 HBV and HCV Tests: Comparison of the 200 and 500 μL Protocols.

Abstract

Clinical management of patients infected with hepatitis B virus (HBV) or hepatitis C virus (HCV) relies on the viral load (VL). The Cobas 5800 system (Roche Diagnostics) can determine VLs in 200 and 500 μL samples, but the performance of each protocol has not been compared. We evaluated the performance of both protocols for the HBV and HCV tests. Precision and linearity were verified using commercial panels. Probit analyses were used to determine limits of detection (LoDs). The results obtained with 336 samples were compared using the 200 and 500 μL protocols. Data from 6,737 retrospective HBV and 768 HCV samples were compared to estimate the effects of the different LoDs on the diagnostic results of the protocols. Correlations between protocols were tested with Spearman's rank correlation coefficients (rho). The precision and linearity of both protocols were verified. The LoDs for the 200 and 500 μL protocols were 6.5 and 2.7 IU/mL for HBV and 29.7 and 8.2 IU/mL for HCV, respectively. The agreement between the protocols ranged from 0.8 to 1.0. The results obtained with the HBV and HCV tests showed a strong correlation (rho=0.994). Only 0.4% of HBV and 0.4% of HCV test results were affected by the LoDs of the 200 μL protocol. The Cobas 5800 200 and 500 μL protocols for the HBV DNA and HCV RNA tests demonstrated excellent performance. These findings establish the 200 μL protocol as a new option for low-volume samples, especially for pediatric and difficult-to-bleed patients.