Person-centered choice and mHealth support for same-day delivery of long-acting injectable cabotegravir (ImPrEP CAB Brasil): a prospective, open-label, multicenter, quasi-experimental implementation study

Background: Long-acting injectable cabotegravir (CAB-LA) offers a promising alternative to daily oral PrEP. However, studies evaluating PrEP choice and mHealth tools designed to support informed PrEP decision-making in real-world public health settings are scarce. We evaluated PrEP choice and the impact of an mHealth tool. Methods: ImPrEP CAB Brasil is a prospective, multicenter, quasi-experimental, implementation study conducted in six public health services in Brazil. Eligible participants were PrEP-naïve cisgender men, transgender and non-binary persons who have sex with men, aged 18-30 years, who tested negative for HIV. Participants were offered a person-centered model that provided a choice between same-day delivery of CAB-LA and oral PrEP. To support informed decision-making, participants were allocated (1:1) to standard-of-care counseling (SOC) or mHealth tool + SOC (first half enrolled in each site received SOC and the remaining received mHealth + SOC). Modified Poisson regression models estimated the effects of exposures of interest, study arm and Decisional Conflict Scale (DCS), on CAB-LA choice. Registered at ClinicalTrials.gov (NCT05515770). Findings: From October-2023 to October-2024, 1447 participants were enrolled: 738 (51.0%) to SOC arm and 709 (49.0%) to mHealth + SOC arm. Overall, 1201 (82.9%) participants chose CAB-LA. Participants allocated to mHealth + SOC arm were more likely to choose CAB-LA compared to SOC (PR: 1.15; 95% CI 1.10-1.21). Higher DCS scores were associated with a lower prevalence ratio of choosing CAB-LA (PR: 0.99; 95% CI 0.98-0.99). A total of 678 (95.7%) participants were satisfied with the mHealth tool and 659 (92.9%) found it supported PrEP decision. Interpretation: We found a strong preference for CAB-LA among young sexual and gender diverse populations. The mHealth intervention was highly acceptable and supported informed-decision, indicating its utility as a scalable strategy in real-world settings. These findings are crucial for guiding the equitable scale-up of CAB-LA and advancing HIV prevention in Latin America. Funding: Unitaid, WHO, Brazilian Ministry of Health.