Diversity of incarceration patterns among people who inject drugs and the association with incident hepatitis C virus infection.

BACKGROUND: Little is known about the relationship between short-term incarceration and risk of hepatitis C virus (HCV) infection among people who inject drugs (PWID). We investigated whether varying patterns of recent incarceration lasting less than two years are associated with HCV acquisition risk in this population. METHODS: We followed prospectively PWID at risk of acquiring HCV infection in Montréal (2004-2019). At 6-month (up until 2011), then 3-month intervals, participants were tested for HCV antibodies or RNA, and self-reported whether they have been incarcerated in each of the previous 6 or 3 months. If incarcerated, they reported the setting and time spent in incarceration. We fit three separate multivariable time-updated Cox regression models, one for each measure of incarceration: any incarceration lasting less than two years (yes/no), incarceration stratified by setting (local police station/provincial prison/no) and incarceration stratified by time in incarceration (≤1 week/>1 week and ≤1 month/>1 month and <2 years/no). RESULTS: Among 709 PWID followed over 2315.2 person-years, HCV incidence was 9.9/100 person-years (95% confidence interval (CI): 8.7-11.2)]. During follow-up, 248 PWID (35.0%) reported at least one recent incarceration episode of less than two years. Overall, compared to PWID who did not experience incarceration in the prior 6 or 3 months, PWID who did were 1.56 (95% CI: 1.13, 2.17) times more likely to acquire HCV. We found no statistically significant difference in the magnitude of associations across categories of setting and time in incarceration (likelihood ratio test P= 0.53 and 0.44, respectively). CONCLUSION: Any recent incarceration lasting less than two years, regardless of the setting and time in incarceration, was associated with an elevated risk of HCV acquisition among PWID. Findings support the need to expand access to harm-reduction programs in short-term incarceration settings and, in parallel, to prioritise public health-oriented alternatives to incarcerating PWID where possible.