Time to PrEP Disengagement and Associated Factors Among Adolescents and Young Adults from Key and Priority Populations in Uganda. A survival Analysis

Background Adolescents and young adults (AYAs) from key and priority populations face persistent challenges with sustained engagement in HIV pre-exposure prophylaxis (PrEP) care. While PrEP initiation has expanded across sub-Saharan Africa, evidence on long-term retention and determinants of disengagement among AYAs remains limited. We examined time to PrEP disengagement and associated factors among AYAs initiating PrEP in eastern Uganda. Methods We conducted a retrospective longitudinal analysis of routinely collected program data for AYAs aged 15-29 years from key and priority populations who initiated PrEP between 2019 and 2025 at Mbale Regional Referral Hospital. Time to PrEP disengagement was assessed using Kaplan-Meier survival analysis and Cox proportional hazards regression. Multivariable models adjusted for sociodemographic, relational, behavioral, and service delivery factors. Sensitivity analyses redefined the time origin to day 91 following PrEP initiation to reflect the programmatic 90-day grace period. Results Among 3,553 AYAs initiating PrEP, the median time to disengagement was 284 days (95% CI: 273-295). The median age was 24 years (interquartile range [IQR]: 20-26). The probability of remaining engaged in PrEP care declined from 60.1% at 90 days to 20.2% at 365 days. Survival patterns differed significantly by population category and sex at birth but not by age group. In adjusted analyses (N = 3,391), knowledge of a partners HIV status (aHR = 2.04; 95% CI: 1.82-2.29) and initiation through community-based services (aHR = 1.42; 95% CI: 1.17-1.72) were associated with faster disengagement. Married participants had lower hazards of disengagement compared with single participants (aHR = 0.69; 95% CI: 0.64-0.76). Reporting an STI syndrome (aHR = 0.42; 95% CI: 0.32-0.55) or recent gender-based violence (aHR = 0.76; 95% CI: 0.60-0.96) was associated with reduced disengagement. Findings were highly consistent in sensitivity analyses using an alternative risk-period definition. Conclusions PrEP disengagement among AYAs occurs rapidly following initiation, with substantial attrition within the first year. Relational factors, service delivery modality, and population-specific vulnerabilities strongly shape retention trajectories. These findings underscore the need for risk-responsive, differentiated PrEP delivery strategies that strengthen partner-based services, integrate STI and GBV screening, and adapt retention support for AYAs in community and facility settings.