Significant decrease in injection risk behaviours among participants in a needle exchange programme.

Background and aims: Sharing of unsterile injection equipment contributes to transmission of hepatitis C virus (HCV), HIV and hepatitis B virus (HBV) among people who inject drugs (PWID) but is largely preventable through needle exchange programmes (NEP). Sweden has been one of the last countries in Europe to scale up access to NEP for PWID, who consequently have high prevalence rates of HCV and HIV. The aim of the study was to investigate demographic and drug-related determinants of injection risk behaviours, sharing of needle/syringe and paraphernalia, and patterns of change over time in subgroups of PWID participating in the Stockholm NEP.Methods: The Stockholm NEP started in 2013 as the first formal NEP in the region. A total of 2860 PWID were included in this prospective open cohort study. The association between demographic and drug-related determinants and injection risk behaviours were analysed at baseline and followed up at 6, 12, 24, 36 and 48 months post-enrolment.Results: The following factors were associated with high levels of injection risk behaviours at inclusion: female gender, homelessness, low education level, younger age, amphetamine use, not in opioid substitution therapy (OST), being HIV negative and being HCV positive. We found an overall significant decrease in injection risk behaviours over time among participants. Not previously investigated in depth, we found that subgroups of participants varied in degrees of injection risk behaviour reduction over time and that women decreased injection risk behaviours faster than men. Enrolment in OST, HIV positive and age <25 years at inclusion were not associated with a decrease in injection risk behaviours over time.Conclusions: In this prospective cohort study over 4 years, we found that NEP participation was associated with a significant decrease in injection risk behaviours.