Factors associated with a reactive HIV blood self-test result among female sex workers and men who have sex with men in Yaoundé and Douala, Cameroon: a cross-sectional study

In Cameroon, where same-sex practices and sex work are criminalised, stigma and fear of disclosure deter key populations—men who have sex with men (MSM) and female sex workers (FSWs)—from facility-based testing; HIV self-testing (HIVST), a triage test whose reactive results require confirmation, has been adopted as a differentiated strategy to reach them. However, the factors associated with a reactive HIV self-test among these populations in the country’s largest cities remain poorly characterised, which limits the geographic and population targeting of prevention and testing. This study aimed to identify the factors associated with a reactive HIV self-test among FSWs and MSM in Yaoundé and Douala, Cameroon. A cross-sectional analytical study was carried out from November 2021 to July 2022 in 17 community-based organisations (10 for MSM, 7 for FSWs) in Yaoundé and Douala. FSWs and MSM aged ≥ 21 years were recruited by voluntary sampling and performed an unassisted blood-based HIV self-test after counselling; data were collected by questionnaire. Associations with a reactive self-test were assessed by modified Poisson regression, yielding adjusted prevalence ratios (aPR) with 95% confidence intervals (CI). Of 789 participants, 435 (55.1%) were FSWs and 354 (44.9%) MSM. Overall, 23.3% (95% CI 20.5–26.4) had a reactive self-test (FSWs 23.2%; MSM 23.4%), and reactivity was more than three times higher in Yaoundé (38.3%) than Douala (12.2%). Among FSWs, reactivity was lower in Douala (aPR 0.22; 0.15–0.34) and, relative to unschooled women, at every level of education (primary 0.28 [0.16–0.50]; secondary 0.34 [0.21–0.54]; higher 0.44 [0.23–0.84]), and higher with a history of STI symptoms (aPR 3.13; 2.20–4.46). Among MSM, reactivity was lower in Douala (aPR 0.31; 0.20–0.50), with secondary education (0.37; 0.18–0.76) and with alcohol consumption (0.65; 0.43–0.98), and higher with each additional sexual partner over six months (aPR 1.03; 1.01–1.05). A reactive self-test was frequent among MSM and FSWs, with a marked concentration in Yaoundé and among FSWs with no formal schooling. Strengthening geographically prioritised and differentiated HIV prevention strategies, combined with STI screening and linkage to confirmatory testing, would help reduce this burden.