Towards elimination of hepatitis C in Oslo: cross-sectional prevalence studies in 2018, 2021, 2022 and 2023

Background:

The prevalence of chronic hepatitis C virus (HCV) infection among people who inject drugs (PWID) in Oslo was stable between 40-50% in the interferon-era. Since 2018, DAA-treatment is offered without restrictions. The aim of this study was to assess changes in HCV prevalence among PWID in Oslo between 2018 and 2023 and risk factors for not being treated.

Methods:

Point prevalence studies were conducted in September 2018, 2021, 2022 and 2023 among PWID in Oslo. Assessments included blood samples and a questionnaire about drug use. We calculated HCV RNA prevalence estimates for each year with Clopper-Pearson 95% confidence intervals and used logistic regression analysis to identify factors associated with detectable HCV RNA.

Results:

A total of 281, 261, 247 and 252 participants were included in 2018, 2021, 2022 and 2023 respectively. 75%, 79%, 84% and 76% reported recent injecting drug use, respectively. HCV RNA prevalence decreased from 26.3% (95% CI 21.3-31.9) in 2018 to 14.2% (95% CI 10.2-19.0) in 2021, 8.9% (95% CI 5.7-13.2) in 2022 and to 6.7% (95% CI 4.0-10.6) in 2023. 

In adjusted analysis, undetectable HCV RNA was associated with participation in 2021 (vs 2018; aOR 0.46; 95% CI 0.27-0.76), participation in 2022 (vs 2018; aOR 0.27; 95% CI 0.15-0.49) and with participation in 2023 (vs 2018; aOR 0.23; 95% CI 0.11-0.44).

Being HCV RNA positive any year was associated with increasing age (per 10-year increase; aOR 1.23; 95% CI 1.01-1.49) and any injecting drug use the past four weeks, included mainly heroin injecting (aOR 2.06; 95% CI 1.09-3.88), mainly amphetamine injecting (aOR 4.71; 95% CI 2.40-9.24) and mixed heroin/amphetamine injecting (aOR 2.84; 95% CI 1.23-6.54).

Conclusion:

A substantial decrease in HCV RNA prevalence among PWID in Oslo between 2018 and 2023 was observed. Recent injecting drug use was associated with being HCV RNA positive.