Performance evaluation of Xpert HBV viral load (VL) assay: Point-of-care molecular test to strengthen and decentralize management of chronic hepatitis B (CHB) infection

Abstract

Introduction: Estimation of hepatitis B (HBV) viral load (VL) is critical in hepatitis-B cascade-of-care and at present there is no point of care (POC) molecular assay available for the same. This study evaluated the performance of a new near point of care molecular assay Xpert HBV- VL assay against the approved assays.

Materials & methods: In this study 172 archived previously tested samples, were simultaneously re-tested for HBV DNA on 3 real-time PCR assays: Abbott Real-Time HBV, Roche TaqMan® HBV and Xpert HBV assay.

Results: Out of 172 samples, 119 were previously positive for HBV DNA with a median VL 4.46 (IQR: 1-8.76)log₁₀IU/mL and 53 were HBV DNA negative. Genotyping could be done in 95 (79.8 %) samples and genotype D (83; 87.3 %) was the commonest type. The Xpert assay demonstrated a good correlation with Abbott (R² = 0.94) and Roche (R² = 0.96). On comparison, the mean difference with 95 % Confidence Interval of Xpert assay was -0.018 and -0.043 log₁₀ IU/mL with Abbott and Roche assay, respectively. The overall sensitivity, specificity, negative predictive value, and positive predictive value of the Xpert assay was found 97.5 %, 100 %, 94.65 & 100 % respectively.

Conclusion: Xpert HBV-VL assay which has a potential for near point of care molecular testing has shown excellent performance and found to be a reliable method for HBV DNA quantification.

Keywords: Chronic hepatitis B; Gene Xpert; HBV DNA; HBV genotype; HBsAg; Real time PCR; Viral load.