Sexually transmitted infection prevalence and testing coverage among people who inject drugs: A systematic review

Individual- and structural-level factors place people who inject drugs at excess risk of sexually transmitted infections (STI). We reviewed existing evidence on STI prevalence and testing coverage among this population.

We conducted searches of peer-reviewed and grey literature for papers or reports published between January 2008 and April 2024. Data were summarised using narrative synthesis, and where appropriate, regional and global estimates weighted by population size of people who inject drugs were generated using random effects meta-analysis. Meta-regressions were undertaken to examine study- and country-level sources of heterogeneity.

Data on STI prevalence and testing coverage were sparse, which precluded meta-analysis except for syphilis prevalence. We estimated global active syphilis prevalence among people who inject drugs as 3.2 % (95 % confidence interval [CI]: 2.3-4.6). There was regional variation, with estimates ranging from 0.1 % (0-0.3) in North America to 7.2 % (3.6-11.7) in Latin America. Based on a small number of studies (n = 12) that stratified estimates by gender, active syphilis prevalence was higher among women (8.1 %, 3.6-13.7) than men (2.3 %, 1.4-3.5). Higher HIV prevalence among people who inject drugs at both study and country level were associated with higher syphilis prevalence. Chlamydia prevalence estimates (n = 22) ranged 0-12.5 %, gonorrhoea prevalence (n = 20) ranged 0-2 %, and past year STI testing uptake (n = 8) ranged 8-62 %.

More evidence on STI prevalence and testing uptake among people who inject drugs is urgently needed. Embedding STI diagnosis and treatment services within bloodborne virus programs could be an effective control measure.