Retention on pre-exposure prophylaxis a comparative analysis of long-acting cabotegravir (CAB-LA) and oral PrEP in Mongu District Zambia

Abstract

Abstract Background Despite advances in HIV prevention, new infections remain high, particularly in low- and middle-income countries. Oral pre-exposure prophylaxis (PrEP) is effective but limited by poor adherence due to daily dosing requirements. Zambia introduced long-acting injectable cabotegravir (CAB-LA) in 2024 to address these challenges. Therefore, this study aimed to compare retention between clients receiving CAB-LA and those on oral PrEP in a real-world programmatic setting in Mongu District, Zambia. Methods A retrospective cohort study was conducted using routine programmatic data from clients initiated on oral PrEP or long-acting cabotegravir (CAB-LA) in Mongu District, Zambia, between October 2024 and September 2025. A total of 424 participants were selected using systematic random sampling from electronic health records. The primary outcome was time to PrEP discontinuation, defined as failure to attend a scheduled visit within three months of the expected appointment. Kaplan–Meier survival analysis and log-rank tests were used to compare retention between groups. Cox proportional hazards regression analysis was performed to identify factors associated with retention, with results reported as adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs). Results The median survival time for the 424 clients was 6 months (interquartile range [IQR]: 3–10). Overall, 23% of participants discontinued PrEP during the follow-up period. However, discontinuation was more common among clients using oral PrEP (Truvada) compared to CAB-LA users (50% vs. 7%, p-value = 0.001). In the Cox proportional hazards model, adjustment was made for PrEP regimen, age, sex, education level, and marital status. Oral PrEP users had a 114% higher hazard of discontinuation compared to CAB-LA users (aHR = 2.14; 95% CI: 1.80–6.52). Furthermore, the model indicated a higher discontinuation associated women aged 15–24 and 25–30 years (compared to ≥ 31 years), females (compared to males), those with primary and secondary education (compared to tertiary education), and participants who were single or divorced (compared to married individuals). Conclusion This study demonstrated that retention on pre-exposure prophylaxis was significantly higher among clients receiving long-acting cabotegravir compared to those using oral PrEP under routine programmatic conditions in Mongu District. Conversely, discontinuation was substantially lower among clients receiving long-acting cabotegravir. Scaling up access to long-acting PrEP has the potential to improve retention in HIV prevention programs and strengthen overall effectiveness in similar resource-limited settings.