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 currently there is no point of care (POC) molecular assay available for that. This study evaluated the performance of a new near point of care molecular assay Xpert HBV-VL assay against FDA approved Real time PCR assays. Materials & methods In this retrospective study 119 archived plasma samples from HBV infected patients, and 53 hepatitis B surface antigen (HBsAg) patients were simultaneously tested for HBV DNA quantification on 2 real time PCR conventional assays and Xpert assay. The routine method for reporting to patient was Abbott Real Time PCR. Results The range of HBV DNA load in samples was 1 to 8.76 log 10 IU/ml with a median load of 4.46 (IQR: 1-8.76) log 10 IU/ml as detected by routine assay (Abbott Real-Time HBV VL assay). Genotyping could be done in 95 (79.8%) samples and genotype D (83; 87.37%) was found commonest. The Xpert assay demonstrated good correlation with Abbott (R 2 = 0.944) and Roche (R 2 = 0.963). On comparison the mean difference (95% Confidence Interval) in average viral load was −0.018 log 10 IU/ml and −0.043 log 10 IU/ml when Xpert was compared with the 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.