Screening haemodialysis patients for hepatitis C in Vietnam: The inconsistency between common hepatitis C virus serological and virological tests

Abstract

Selecting the appropriate screening method and interval for the early detection of hepatitis C virus (HCV) infection in low-resourced haemodialysis settings is a challenge. The challenge occurs when patients are classified as HCV-RNA positive but negative to HCV-core antigen (HCV-coreAg), anti-HCV and genotyping tests. We aim to clarify the inconsistency between HCV-RNA, HCV-coreAg, anti-HCV and HCV genotyping tests in haemodialysis patients and determine the reliability of HCV-coreAg as a routine two-monthly screening strategy. Haemodialysis patients were tested every 2 months between 2012 and 2014 at the largest district haemodialysis unit in Ho Chi Minh City, Vietnam, for aminotransferases, anti-HCV antibodies, HCV-coreAg, HCV-RNA and HCV genotype. HCV-coreAg and anti-HCV results were tested against HCV-RNA for sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV). All 201 patients participated in the study. The HCV-coreAg test performed better than the anti-HCV test for sensitivity (100% vs 31%), NPV (100% vs 90%) and accuracy (100% vs 90%). The HCV-coreAg and anti-HCV tests performed no differently for specificity (100% and 98%, respectively) or PPV (100% and 73%, respectively). Kappa values for HCV-coreAg and anti-HCV tests were 1 and 0.39, respectively. Early detection of HCV for the purpose of infection prevention requires a high level of sensitivity and HCV-coreAg performed better in our chronic haemodialysis population as a two-monthly screening method than routine anti-HCV testing. HCV-coreAg test is less labour-intensive with a higher level of accuracy in patients with low viral loads making it cost effective for low-resourced settings. Repeating genotyping may be required in HCV-coreAg positive patients with a low viral load.