Oral PrEP continuation rates among key populations in Nigeria: a retrospective cohort study of a large-scale HIV prevention programme.

INTRODUCTION: Pre-exposure prophylaxis (PrEP) is an effective HIV prevention strategy, but its impact is limited by low uptake and poor continuation rates. This study investigates oral PrEP continuation among key populations (KPs) enrolled in an HIV prevention programme across seven states in Nigeria, representing one of the largest longitudinal PrEP continuation studies in Sub-Saharan Africa to date. METHODS: We analysed data from 43 788 clients who initiated daily oral PrEP between January 2020 and March 2023. The sample comprised female sex workers (20 574, 47.0%), men who have sex with men (12 946, 29.6%), people who inject drugs (9462, 21.6%) and transgender individuals (806, 1.8%). The primary outcome was 6-month PrEP continuation, defined as having a recorded PrEP refill more than 6 months after initiation. We used multivariable mixed-effects logistic regression to identify factors associated with PrEP continuation; the model included KP group, age, education, occupation, marital status and time since PrEP initiation and accounted for clustering at the facility level. RESULTS: Among the 43 788 clients initiating PrEP, the 6-month continuation rate was 11.5%. Female sex workers had the highest 6-month continuation rate (13.7%), while transgender individuals had the lowest (3.5%; adjusted OR (aOR) 0.37 (0.24-0.55), compared with female sex workers). The continuation rate generally increased with age; the oldest clients (≥40 years) had a significantly higher continuation rate than those aged 18-24 (12.9% vs 11.0%; aOR 1.15 (1.02-1.29)). Unemployment was also associated with a small but significant reduction in continuation, with a rate of 11.8% for unemployed clients compared with 12.1% for employed clients (aOR 0.86 (0.79-0.94)). CONCLUSION: These findings highlight the need for targeted interventions to improve PrEP continuation among KPs in Nigeria, particularly for younger clients and transgender people.