Chemsex and uptake of HIV pre-exposure prophylaxis among adult cisgender gay, bisexual and other men who have sex with men worldwide: a systematic review with meta-analysis.

Background: There is a lack of summarized information regarding the uptake of pre-exposure prophylaxis (PrEP) among HIV negative gay, bisexual and other men who have sex with men (GBMSM) who engage in chemsex. This systematic review and meta-analysis aimed to summarize, assess the quality of existing evidence, estimate the prevalence of PrEP uptake among GBMSM who engage in chemsex, based on available global evidence; and evaluate whether engagement in chemsex is associated with increased odds of PrEP uptake in this population. Methods: We searched Medline, Embase, Cochrane Reviews and CENTRAL, APA PsycInfo, Scopus, and LILACS. We included studies reporting chemsex practices among adult cisgender GBMSM and PrEP uptake until July 1, 2025. Evidence quality was assessed using the Newcastle-Ottawa Scale tool. Chemsex exposure was analyzed using two timeframe groups: recent (past 6 months) and ever (any longer or unspecified timeframe). Prevalence and associations -odds ratio (OR)- were pooled in meta-analyses using a random-effect model. Inconsistency, sensitivity, and publication bias analyses were conducted. PROSPERO registration: CRD42024573871. Findings: Among 3988 records screened, 28 studies comprising 36,339 participants across three world regions were included: Western and Central Europe and North America, Asia and the Pacific, and Latin America; all were rated low to moderate quality. The overall prevalence of PrEP use was 39% (95% CI: 29-49%) among GBMSM who engaged in chemsex, with no significant differences between Interpretation: Our findings suggest that PrEP use is relatively common among GBMSM who engage in chemsex globally and chemsex is consistently and strongly associated with increased PrEP uptake in this population. The association between chemsex and PrEP use was significantly higher in studies from high-income settings, where chemsex practices are better described and PrEP is more widely available for this group. The lack of standardized definitions in the field contributes to the high heterogeneity and strongly influences the generation of global evidence. This first systematic review and metanalysis in the field highlights the need to expand and integrate chemsex harm reduction and PrEP services for GBMSM, especially in low- and middle-income settings, to improve health outcomes and advance towards the global HIV elimination goals. Funding: Publication fees were sponsored by the Research Group of the HIV Unit, Infectious Disease Division, Department of Medicine, Geneva University Hospitals, Geneva, Switzerland. The Covidence membership and the fees for an academic librarian developing a professional systematic search strategy were sponsored by the Research Group of the HIV Unit, Infectious Diseases Service, Hospital Clinic, and IDIBAPS, University of Barcelona, Barcelona, Spain. No further funding was received for this study.