Background People who inject drugs (PWID) may engage in sexual behaviours that increase their HIV and hepatitis C virus (HCV) risk, including sex work and male-with-male sexual activity. We undertook a global systematic review to assess whether PWID who engage in these behaviours have higher HIV and HCV acquisition risks. Methods In this systematic review and meta-analysis, we searched MEDLINE, Embase, and PsycINFO for studies among PWID published between 01/01/2000 and 09/06/2026 that included estimates of the association between male-with-male sex or sex work and our primary outcomes of HIV or HCV incidence. Studies that estimated incidence by longitudinally re-testing people at risk of infection or by using assays for recent infection were eligible for inclusion. We also contacted authors for unpublished estimates. We pooled estimates using random-effects meta-analysis. We used I2 to assess heterogeneity, and we used Egger's test to assess publication asymmetry. This review is registered with Prospero (CRD42020220884). Findings We included 57 studies comprising 164 estimates. Among men, recent male-with-male sex was associated with higher HIV acquisition (pooled incidence rate ratio (IRR):2.35; 95% CI: 1.51–3.66; I2: 51%).) but not HCV (IRR: 1.28; 95% CI: 0.95–1.72; I2: 21%). Recent sex work had a 1.72-fold (95% CI: 1.30–2.28; I2: 65%) and 1.59-fold (95% CI: 1.29–1.96; I2: 60%) higher HIV and HCV acquisition risk among all PWID, respectively. When stratified, sex work was associated with higher HIV acquisition among women (IRR: 2.30; 95% CI: 1.44–3.68; I2: 68%) but not men (IRR: 1.43; 95% CI: 0.92–2.22; I2: 51%), and was associated with HCV acquisition among men (IRR: 1.51; 95% CI: 1.22–1.87; I2: 0%), but not women (IRR: 1.26; 95% CI: 0.90–1.77; I2: 55%). For lifetime behaviours, only male-with-male sex was associated with HIV acquisition (IRR: 2.44; 95% CI: 1.18–5.02; I2 = 87%). Results from Egger's tests did not provide evidence of asymmetry bias for our pooled estimates, while I2 measures suggested considerable heterogeneity for many outcomes. Interpretation PWID who also engage in sex work or male-with-male sex were found to have higher HIV or HCV acquisition risks. Future research should aim to understand the mechanisms driving these associations. Funding Medical Research Council Greater Western Four Partnership Doctoral Training Partnership, Wellcome Trust, Canadian Institutes of Health Research and Medical Research Council.
Digital technology is a ubiquitous part of adolescent life, yet progress in understanding its implications for health and development is constrained by the lack of standardised, developmentally appropriate measurement tools. This systematized scoping review, conducted following PRISMA-ScR guidelines, identifies and evaluates instruments used to measure adolescent digital technology use between 2014 and December 14 2025. Searches in PubMed, Scopus, and Web of Science yielded 533 peer-reviewed studies, from which 135 validated measurement instruments were identified. We extracted data on instrument characteristics and conducted a secondary search to evaluate psychometric properties using adapted COSMIN criteria. Most tools relied on self-reported frequency or duration of use, with 63% designed to detect problematic behaviours—such as social media addiction or gaming disorder—often using adult-derived clinical criteria. Fewer than 2% of instruments assessed positive or developmentally beneficial use. Tools frequently lacked adolescent-specific content, cultural adaptation, and validation across sociodemographic subgroups, and objective or multi-method measures were rare. Current measurement practices are heavily risk-focused and often insufficiently tailored to adolescents' developmental and sociocultural contexts. This review lays the foundation for WHO's efforts to develop more balanced, psychometrically robust, and culturally sensitive approaches to measuring adolescent digital technology use. Funding None.
