Hepatitis C virus core antigen: A potential alternative to HCV RNA testing among persons with substance use disorders

Background The hepatitis C virus (HCV) core antigen (HCVcAg) may be an alternative diagnostic method to HCV RNA especially in populations such as substance users, the homeless or in resource-limited settings. Aims To evaluate performance of HCVcAg test in patients with opioid use disorder (OUD) on methadone in order to document its performance characteristics in the target population and to ensure that its specificity remains consistent across different populations. Methods HCVcAg levels from 109 methadone-maintained patients were compared to HCV RNA levels. Results Mean age was 53.8 ± 7.8 years, 59.6% were male, 68.8% African American, and 44% HCV-infected. HCVcAg was detectable in 47 of 48 HCV-infected, and undetectable in all HCV RNA negative patients. The HCVcAg assay had sensitivity of 97.9% and specificity of 100%. Correlation with HCV RNA levels was excellent (r = 0.88, 95% CI 0.76; 0.95, p < 0.01). Conclusion HCVcAg has excellent performance for the diagnosis of HCV infection in patients with OUD on methadone.