Younger age as a key predictor of follow‐up abandonment among <scp>PrEP</scp> users: A retrospective cohort study in Madrid

INTRODUCTION: Pre-Exposure Prophylaxis (PrEP) is a cornerstone of HIV prevention, yet its population-level impact is limited by clinical attrition. This study analyses the sociodemographic and behavioural factors associated with follow-up abandonment in a tertiary hospital cohort in Madrid. METHODS: A retrospective cohort study (August 2022-July 2025) was conducted involving 665 participants who initiated oral FTC/TDF PrEP (of 693 individuals assessed) at Hospital Universitario Ramón y Cajal. Abandonment was defined as a >90-day lapse in contact beyond the scheduled visit or medication exhaustion. Independent predictors of discontinuation were identified using Cox proportional hazards regression. RESULTS: Follow-up abandonment occurred in 21.2% (n = 141) (median age: 36.5 years). Three HIV infections were recorded (3/693; 0.43%), with only one occurring during active use. Multivariate analysis identified younger age as the primary predictor of abandonment, with a 5% risk reduction for every additional year of age (HR 0.95; 95% CI 0.92-0.98; p < 0.001). Prior healthcare engagement, evidenced by HBV immunity (anti-HBs+), was significantly protective against attrition (HR 0.52; 95% CI 0.34-0.80; p = 0.003). Transgender women showed a trend towards higher abandonment (HR 3.11, p = 0.060). Notably, contracting a sexually transmitted infection (STI) during follow-up correlated with higher retention, likely due to increased clinical touchpoints and heightened risk perception. CONCLUSIONS: Younger individuals face the highest risk of PrEP discontinuation despite being the demographic most vulnerable to HIV acquisition. Retention is driven more by structural healthcare integration and age than by individual risk behaviours. To improve persistence, healthcare systems must transition towards flexible, digital and decentralized care models tailored to younger, system-naïve users.