Towards elimination of hepatitis C in Oslo: Cross-sectional prevalence studies among people who inject drugs.

BACKGROUND: Norway aims to eliminate hepatitis C virus (HCV) infection within the end of 2023. Before the introduction of direct-acting antivirals, the prevalence of chronic HCV infection among people who inject drugs (PWID) in Oslo was 40-45 %. The primary aim of the study was to assess changes in HCV prevalence among PWID in Oslo from 2018 to 2021. The secondary aim was to assess change in prevalence in selected subgroups. METHODS: Point prevalence studies were conducted in 2018 and 2021 among PWID attending low-threshold health services in downtown Oslo. Assessments included blood samples analysed for anti-HCV and HCV RNA, and a questionnaire about drug use. Information about previous HCV treatment was only collected in the 2021 cohort. We calculated HCV RNA prevalence estimates for 2018 and 2021 and used logistic regression analysis to identify factors associated with detectable HCV RNA and previous HCV treatment. RESULTS: A total of 281 and 261 participants were included in 2018 and 2021, respectively. The median age was 40.6 and 44.0 years, 73.7 % and 72.8 % were men, and 74.5 % and 78.6 % reported recent (past four weeks) injecting drug use, respectively. HCV RNA prevalence decreased significantly from 26.3 % (95 % CI 21.3-31.9) in 2018 (74 of 281) to 14.2 % (95 % CI 10.2-19.0) in 2021 (37 of 261). The odds of detectable HCV RNA were significantly lower in 2021 compared to 2018 (aOR 0.41; 95 % CI 0.26-0.67). In the 2021 cohort, detectable HCV RNA was associated with recent amphetamine injecting (aOR 7.21; 95 % CI 1.41-36.95), and mixed heroin/amphetamine injecting (aOR 7.97; 95 % CI 1.55-41.07). The odds of previous treatment were lower among women (aOR 0.52; 95 % CI 0.27-1.00). CONCLUSION: A substantial decrease in HCV RNA prevalence among PWID in Oslo between 2018 and 2021 was observed. To reach elimination, adaptive services must be further developed.

Hepatitis C treatment uptake among people who inject drugs in Oslo, Norway: A registry-based study.

BACKGROUND: Improving HCV treatment uptake among people who inject drugs (PWID) is crucial to achieving the WHO elimination targets. The aims were to evaluate HCV treatment uptake and HCV RNA prevalence in a large cohort of PWID in Norway. METHODS: Registry-based observational study where all users of the City of Oslo's low-threshold social and health services for PWID between 2010-2016 (n = 5330) were linked to HCV notifications (1990-2019) and dispensions of HCV treatment, opioid agonist treatment (OAT) and benzodiazepines (2004-2019). Cases were weighted to account for spontaneous HCV clearance. Treatment rates were calculated using person-time of observation, and factors associated with treatment uptake were analysed using logistic regression. HCV RNA prevalence was estimated among individuals alive by the end of 2019. RESULTS: Among 2436 participants with chronic HCV infection (mean age 46.8 years, 30.7% female, 73.3% OAT), 1118 (45.9%) had received HCV treatment between 2010-2019 (88.7% DAA-based). Treatment rates increased from 1.4/100 PY (95% CI 1.1-1.8) in the pre-DAA period (2010-2013) to 3.5/100 PY (95% CI 3.0-4.0) in the early DAA period (2014-2016; fibrosis restrictions) and 18.4/100 PY (95% CI 17.2-19.7) in the late DAA period (2017-2019; no restrictions). Treatment rates for 2018 and 2019 exceeded a previously modelled elimination threshold of 50/1000 PWID. Treatment uptake was less likely among women (aOR 0.74; 95% CI 0.62-0.89) and those aged 40-49 years (aOR 0.74; 95% CI 0.56-0.97), and more likely among participants with current OAT (aOR 1.21; 95% CI 1.01-1.45). The estimated HCV RNA prevalence by the end of 2019 was 23.6% (95% CI 22.3-24.9). CONCLUSION: Although HCV treatment uptake among PWID increased, strategies to improve treatment among women and individuals not engaged in OAT should be addressed.

Hepatitis C treatment and reinfection surveillance among people who inject drugs in a low-threshold program in Oslo, Norway.

BACKGROUND: The aims were to evaluate HCV treatment effectiveness, estimate reinfection rates, and demonstrate the feasibility of reinfection surveillance and retreatment among marginalized people who inject drugs (PWID). METHODS: Prospective observational study including consecutive HCV RNA positive individuals attending a low-threshold clinic in Oslo, Norway, between 2013 and 2020. Participants were offered individually tailored HCV treatment and post-treatment HCV RNA surveillance at three months intervals. RESULTS: Of 488 HCV RNA positive individuals, 363 initiated treatment (median age 48.7 years, 72.5% male, 17.2% liver cirrhosis, 54.3% unstable housing). All participants had a history of injecting drug use, 71.1% received opioid agonist treatment, and 70.1% reported recent (past 3 months) injecting. In intention-to-treat analysis, excluding those with HCV RNA results pending, virologic response was achieved in 306 of 340 (90.0%) participants. In modified intention-to-treat analysis, also excluding those with loss to follow-up during treatment, virologic response was achieved in 306 of 323 (94.7%). Virologic response was not associated with recent injecting drug use or socio-demographic factors. Reinfection surveillance was accomplished in 297 individuals (308.2 PY of follow-up; median 0.50 years). Eight cases of reinfection were detected for an incidence of 2.60/100 PY (95% CI 1.12-5.11) overall, and 3.74/100 PY (95% CI 1.62-7.37) among those with injecting drug use during follow-up (n = 205). Reinfection was associated with younger age (IRR 0.37; 95% CI 0.18-0.74), and all cases occurred in participants aged below 49 years with ongoing injecting drug use who reported mixed heroin/amphetamine injecting. Successful retreatment was provided in all cases and no second reinfections were observed. CONCLUSION: The findings consolidate previous evidence supporting the effectiveness of HCV treatment among PWID, provide novel data on reinfection rates and associated factors, and demonstrate the feasibility of reinfection surveillance and retreatment in a real-world setting.