Evaluation of Hepatitis B and Hepatitis C Viral Load Detection by Point of Care Test GeneXpert: A Pilot Study

Abstract

The new Xpert HBV and HCV Viral load tests (used with GeneXpert) are in vitro nucleic acid amplification tests for the quantitation of hepatitis B virus DNA and hepatitis C virus RNA in human plasma or serum. This system was used as the point of care test based on fully automated processing real-time PCR and used to diagnose and assess treatment response. To evaluate performance of GeneXpert, COBAS system (U.S. FDA-approved) was used to compare by using Pearson’s correlation coefficient: r, simple regression analysis: R² as well as agreement measurement by Bland-Altman plot and analysis and intraclass correlation coefficient (ICC).  Forty EDTA plasma for HBV VL and 40 EDTA plasma for HCV VL were used in this study.  The results showed that Pearson’s correlation coefficient: r and regression: R² of HBV VL were 0.9916 and 0.9833 respectively while HCV VL were 0.9375 and 0.8774 respectively. For agreement measurement by Bland-Altman plot, 27 from 30 samples (90.0 %) were in bias + 1.96 SD of HBV VL (0.5304 to -0.6209) and 30 from 31 samples (96.8 %) were in + 1.96 SD of HCV VL (0.7072   to -0.5669).  Also 14 from 30 cases of the HBV VL and 18 from 31 cases of the HCV VL by GeneXpert were lower than by COBAS.  Moreover, the ICC of both HBV (0.996) and HCV VL (0.967) were excellent.  In conclusion, the HBV and HCV VL by GeneXpert were comparable to COBAS system for diagnosis and patient management after treatment.