Non-fatal overdoses and related risk factors among people who inject drugs in St. Petersburg, Russia and Kohtla-Järve, Estonia.

Background: This study seeks to identify the prevalence of, and risk factors associated with, non-fatal overdose among people currently injecting drugs (PWID) in St. Petersburg (Russia) and in Kohtla-Järve (Estonia).
Methods: Five hundred eighty-eight study participants in Kohtla-Järve (in 2012) and 811 in St. Petersburg (in 2012-2013) were recruited using respondent driven sampling for interviewing and HIV testing.
Results: Three-quarters (76%) of the current PWID were male. Participants from St. Petersburg were older (mean age 32.1 vs. 29.6 years, p < 0.0001) and reported a longer average duration of injecting drugs (mean duration: 13.3 vs. 10.9 years, p < 0.0001). Main drugs injected were opioids (fentanyl in Kohtla-Järve, heroin in St Petersburg). HIV prevalence was 63% (95% CI 59-67%) in Kohtla-Järve and 56% (95% CI 52-59%) in St. Petersburg. Two thirds of the PWID in Kohtla-Järve and St. Petersburg reported ever having experienced a drug overdose involving loss of consciousness or stopping breathing. In Kohtla-Järve, 28% (95% CI 24-31%) of participants and, in St Petersburg, 16% (95% CI 14-19%) of participants reported an overdose within the previous 12 months. Characteristics of injection drug use practice (longer duration of injection drug use, main drug injected), correlates of high-risk injection behaviour (higher injecting frequency, sharing), and problem alcohol use were associated with the risk of overdose within the previous 12 months. The significant factors effects did not differ between the sites.
Conclusions: PWID are at high risk for overdose. Effective overdose prevention efforts at the public health scale are therefore warranted.