Utility of a one-step screening and diagnosis strategy for viremic HCV infection among people who inject drugs in Catalonia.

Background: In Catalonia (Spain), people who inject drugs (PWID) face numerous barriers to access to mainstream healthcare services for hepatitis C confirmatory diagnosis and treatment, so simplified testing strategies for viremic infection are urgently needed. Among PWID attending harm-reduction services in Catalonia, we aimed (i) to assess the utility of an in-house HCV-RNA detection assay on dried blood spots (DBS) as a one-step screening and confirmatory diagnosis strategy for hepatitis C, (ii) to estimate the prevalence of viremic HCV infection, and (iii) to identify factors associated with unawareness of viremic infection.

Methods: A cross-sectional study of current PWID (N  = 410) was performed in four harm-reduction services. All participants underwent HCV antibody point-of-care testing and parallel DBS collection for centralized RNA testing. An epidemiological questionnaire was administered. Paired EDTA-plasma samples were additionally collected for HCV viral load testing in 300 participants.

Results: HCV-RNA testing from DBS was feasible and showed 97.2% sensitivity and 100% specificity for viral loads >3000 IU/mL in real-life conditions. No significant differences in the performance when detecting viremic infections were observed between this one-step testing strategy vs. the conventional two-step algorithm involving venepuncture. Overall HCV seroprevalence was 79.8%, and prevalence of viremic infection was 58.5%. Importantly, 35.8% of viremic HCV participants were unaware of their status, and no specific socio-demographic or bio-behavioral factors independently associated with unawareness of viremic infection were identified. Among participants reporting a past or current HCV infection, 29.0% stated having received HCV antiviral treatment.

Conclusion: The high viremic HCV infection burden among PWID attending HRS, estimated for the first time in Catalonia, together with the low levels of awareness of viremic status and access to treatment, suggest that scaling up this one-step screening and diagnosis strategy to the network of harm-reduction services would help to achieve HCV elimination targets set by the World Health Organization.