Clinical utility of hepatitis C virus core antigen (HCVcAg) assay to identify active HCV infection in hemodialysis and renal transplant patients

Background The prevalence of HCV infection is high and it is a major cause of liver-related morbidity and mortality in hemodialysis and renal transplant patients. Diagnosis of hepatitis C virus (HCV) infection requires both HCV antibody screening and confirmatory nucleic acid testing (NAT). Hepatitis C virus core antigen (HCVcAg) is a reliable direct viral marker to identify active HCV infection. Aim To assess the clinical utility of HCV core antigen to identify active HCV infection in hemodialysis and renal transplant patients. Methods A representative total of 231 plasma samples with a predominance of low viral load were included for HCVcAg testing and its performance characteristics were compared with the gold standard HCV RNA. Results Comparison of HCVcAg with HCV RNA showed an excellent specificity of 99% (95% CI: 94.7 to 100%) and sensitivity of 80.62% (95% CI: 73.59 to 87.7%). Likewise, the PPV and NPV of HCVcAg were 99.1% (95% CI: 93.7% to 99.9%) and 80.2% (95% CI: 74% to 85.2%) respectively. The correlation between HCVcAg and HCV RNA was found to be good (R-2 = 0.86, p<0.0001). Among common Indian HCV genotypes (1, 3 & 4), good correlation was observed between HCV RNA and HCVcAg (R-2 = 0.81, p <0.0001). Conclusions It is the first Indian study to show that HCVcAg is a reliable, cost-effective direct marker to identify active HCV infection in hemodialysis and renal transplant patients. Implementation of HCVcAg testing could improve the accessibility to efficacious and affordable disease management in hemodialysis and renal transplant patients. In HCVcAg negative cases, sequential testing with anti-HCV antibody followed by HCV RNA could be a reliable and cost-effective approach.