Hepatitis C Virus (HCV) Core Antigen Reliably Diagnoses HCV Infection in Injection and Non-injection Drug Users
Aims: To demonstrate that HCV core antigen can be a reliable means of diagnosing HCV infection in populations that are difficult to engage.
Methods: Levels of HCV core Ag from 109 patients were compared to HCV RNA levels Assay agreement and associations between baseline predictors were investigated using linear regression.
Results: The mean age was 53.8 years, 59.6% were male, 68.8% African American, and 28.4% were Hispanic. A history of injection and non-injection drug use was reported by 60% and 94% of patients respectively. Active (i.e. previous 6 months) injection and non-injection drug use was reported by 10% and 50% of patients respectively. HCV RNA was detected in 44% of patients, the majority (77%) infected with HCV genotype1. Among HCV RNA (+) patients, 29% (14/48) were HCV / HIV co-infected. HCV core antigen was detectable in 47 of 48 HCV RNA positive patients. Core antigen was not detected in any HCV RNA negative patients. In comparison with HCV RNA levels, HCV Core Ag had excellent performance with a sensitivity of 97.9%, specificity of 100%, and positive and negative predictive value of 100%. We found high correlation between HCV RNA and HCV Core antigen assays with a correlation coefficient of 0.88 (95% CI 0.76; 0.95, p<0.01).
Conclusions: Among injection and non- injection drug users, the HCV core antigen has excellent performance for the diagnosis of active HCV infection. These data underscore its potential for development as a Point of Care test for HCV diagnosis in difficult to engage populations, such as patients with substance use disorders.