Screening for hepatitis C in a general adult population in a low-prevalence area: the Tromsø study.

Background: Chronic hepatitis C virus (HCV) infection can progress to cirrhosis and end-stage liver disease in a substantial proportion of patients. The infection is frequently asymptomatic, leaving many infected individuals unaware of the diagnosis until complications occur. This advocates the screening of healthy individuals. The aim of this study was to estimate the prevalence of HCV infection in the general adult population of the municipality of Tromsø, Norway, and to evaluate the efficiency of such an approach in a presumed low-prevalence area.

Methods: The study was part of the seventh survey of the Tromsø Study (Tromsø 7) in 2015-2016. Sera from 20,946 individuals aged 40 years and older were analysed for antibodies to HCV (anti-HCV). A positive anti-HCV test was followed up with a new blood test for HCV RNA, and the result of any previous laboratory HCV data were recorded. Samples positive for anti-HCV and negative for HCV RNA were tested with a recombinant immunoblot assay. All HCV RNA positive individuals were offered clinical evaluation.

Results: Among 20,946 participants, HCV RNA was detected in 33 (0.2%; 95% CI: 0.1-0.3), of whom 13 (39.4%; 95% CI: 22.7-56.1) were unaware of their infection. The anti-HCV test was confirmed positive in 134 individuals (0.6%; 95% CI: 0.5-0.7) with the highest prevalence in the age group 50-59 years. Current or treatment-recovered chronic HCV-infection was found in 85 individuals (0.4%; 95% CI: 0.3-0.5) and was associated with an unfavorable psychosocial profile.

Conclusion: In this population-based study, the prevalence of viraemic HCV infection was 0.2%. A substantial proportion (39%) of persons with viraemic disease was not aware of their infectious status, which suggests that the current screening strategy of individuals with high risk of infection may be an inadequate approach to identify chronic HCV infection hidden in the general population.