Abstract
BACKGROUND: Suboptimal adherence to pre-exposure prophylaxis (PrEP) limits its global impact, with current evidence mostly from the Global North and lacking Global South perspectives. This meta-analysis synthesizes the rates and determinants of suboptimal adherence to oral PrEP among men who have sex with men (MSM) in both regions. METHODS: We searched for literature describing PrEP adherence and its determinants among MSM globally up until October 2024 to conduct a meta-analysis on the rate and determinants of suboptimal adherence in both regions. The definition of (sub-)optimal adherence was study based. RESULTS: We included 82 studies in the meta-analysis, with 24, 53, and 5 stemmed from the Global South, North, and global multicenter studies, respectively. Oral PrEP suboptimal adherence is prevalent among MSM PrEP users globally (rate = 0.33, 95% confidence interval [CI]: 0.28 to 0.38) with a significantly higher rate ( P = 0.021) in the Global South (rate = 0.41, 95% CI: 0.33 to 0.50) than in the Global North (rate = 0.29, 95% CI: 0.23 to 0.35). In the Global South, older age (OR = 0.57, 95% CI: 0.37 to 0.87), alcohol use (OR = 1.28, 95% CI: 1.02 to 1.60), and presenting depressive symptoms (OR = 1.47, 95% CI: 1.01 to 2.16) were associated with suboptimal adherence. In the Global North, MSM self-identified as Black (OR = 2.27, 95% CI: 1.31 to 3.95) or Other (OR = 1.36, 95% CI: 1.02 to 1.81), having a university degree (OR = 0.50, 95% CI: 0.34 to 0.73), and presenting depressive symptoms (OR = 2.26, 95% CI: 1.35 to 3.78) were associated with suboptimal adherence. On-demand PrEP users globally demonstrated a higher likelihood of suboptimal adherence (OR = 1.59, 95% CI: 1.18 to 2.14). CONCLUSIONS: Suboptimal adherence to oral PrEP is prevalent among MSM globally, particularly higher in the Global South. Regional differences in determinants highlight the need for tailored interventions. Tailored interventions are required to address mental health with tailored efforts to younger MSM in the Global South, while interventions in the Global North should be tailored to specific subgroups.