HCV treatment uptake in people who have injected drugs - observations in a large cohort that received addiction treatment 1970-1984

Objectives: The aim of this study was to document antiviral treatment uptake among former or current people who inject drugs (PWID) with chronic hepatitis C and to explore a possible association between treatment and mortality.

Material and methods: This is a longitudinal cohort study of PWID admitted for drug abuse treatment 1970-1984. The 245 hepatitis C virus (HCV) RNA-positive patients alive by the end of 1996 were followed 1997-2012 through linkage to several health registers. Treatment uptake was mainly documented by information on prescription of antiviral medication registered in the Norwegian Prescription Database from 2004. Cox regression, with a time-dependent covariate measuring end-of-treatment, was employed to evaluate mortality after treatment.

Results: At the end of the follow-up, median time since HCV exposure was 36 years, and 19.2% (47/245) had been prescribed antiviral treatment for chronic HCV infection. No gender difference was observed. Among those alive at the end of the study period, 27.8% (44/158) had been treated. Relative hazard of death was 0.21 (95% confidence interval [CI] 0.07-0.68), comparing periods for patients after versus before or without treatment. Mortality rate after treatment was 0.8 per 100 person years (95% CI 0.3-2.4) compared to 2.8 (95% CI 2.2-3.5) in untreated patients and before treatment. The most important causes of death among the untreated were drug-related.

Conclusions: Among PWID infected with HCV, approximately one-fourth of those still alive at a median of 36 years after exposure had received HCV treatment. Treatment was associated with increased survival, probably mainly due to selection bias.