Adoption and effectiveness of community-based ART initiation among key populations in Cameroon: a Type 1 hybrid effectiveness–implementation study using overlap weighting

Abstract Background. Key populations carry a disproportionate HIV burden but face structural barriers to treatment, especially where same-sex practices and sex work are criminalised. Cameroon adopted community-based ART initiation (CBARTI) in 2023, yet its uptake and effectiveness among key populations were unknow. Within a Type 1 hybrid effectiveness–implementation design, we assessed the adoption and effectiveness of CBARTI relative to standard facility-based ("handshake") initiation. Methods. We conducted a quasi-experimental, post-test-only study with a non-randomised comparison group in Yaoundé and Douala. We enrolled 288 key-population members living with HIV who had been on ART for ≥12 months (134 community-initiated, 154 facility-initiated). Outcomes followed Proctor's taxonomy: adoption (implementation), same-day ART initiation (service), and viral suppression (≤40 copies/mL) and health-related quality of life (HRQoL; WHOQOL-HIV BREF) (client). Reasons for the choice of initiation site were analysed qualitatively by lexical analysis and thematic grouping. Measured confounding was addressed with propensity-score overlap weighting. Weighted risk ratios (RRw) for same day ART inititation was estimated by modified Poisson regression; for viral suppression, it was estimated by Firth penalised-likelihood Poisson regression with a Morel correction; ratios of mean HRQoL domain scores were estimated by robust Gamma regression. Results. Among 158 newly diagnosed individuals free to choose their site, 134 (84.8%; 95% CI 78.2–90.0) chose community initiation. The leading reasons for choosing community initiation were community and peer support, proximity and ease of access, promptness of initiation, and privacy/confidentiality , whereas facility choice rested mainly on proximity and trust in providers . After overlap weighting, same-day initiation was 29% more likely with CBARTI (RR 1.29 (95% CI 1.11–1.50)). Conditional viral suppression was high in both arms but 12% lower in the intervention arm (RR 0.88 (95% CI 0.79–0.98)). HRQoL was comparable across five of six domains; only social relationships was 18% lower with CBARTI (ratio of mean scores 0.82 (95% CI 0.77–0.87). Conclusions. CBARTI was widely adopted and accelerated ART initiation without compromising most quality-of-life domains. Lower conditional viral suppression and social-relationship scores most likely reflect expanded reach rather than inferior care. Scale-up should embed adherence support, viral-load monitoring and psychosocial and stigma-reduction services within a strengthened community–facility continuum.