Objectives Whether regular HIV testing and counselling reduce risky sexual behaviours in African men who have sex with men (MSM) is still a matter for debate. We aimed to identify behavioural trajectories based on HIV risk exposure (HRE) and factors affecting their evolution.

Methods Data were collected from 621 HIV-negative West African MSM (Mali, Cote d'Ivoire, Burkina Faso and Togo) included in a community-based cohort providing quarterly HIV testing and counselling. Sociobehavioural data were collected every 6 months. HRE was defined as reporting inconsistent condom use during receptive anal sex with male partners of unknown HIV status in the previous 6 months. Using 18-month follow-up data, group-based trajectory modelling helped identify behavioural trajectories and determine the factors associated with their evolution. HIV seroconversions (n=67) were specified in each group trajectory.

Results Two distinct group trajectories were identified: medium-risk exposure MSM (ME-MSM) (61%, 6.4% of whom having seroconverted) and high-risk exposure MSM (HE-MSM) (39%, 17.5% of whom having seroconverted). A significant declining trend in the probability of reporting HRE over time ((95% CI)) was observed for HE-MSM (from 0.59 (0.48 to 0.70) at M0 to 0.31 (0.22 to 0.41) at M18), while it remained constant for ME-MSM (0.034 (0.0 to 0.079)). This can be explained by a progressive use of risk reduction strategies (less receptive anal sex, better knowledge of their partners’ status and increasing condom use). Being younger, living in Burkina Faso, self-considering both a man and a woman and reporting a higher level of depression were all associated with HE membership. Among HE-MSM, HRE was higher in those practising transactional or group sex and those experiencing psychological harassment.

Conclusions Quarterly HIV testing and counselling seem to reduce risky sexual behaviours in HIV-negative MSM at greatest risk of infection. Specific support for young MSM, focusing on identity and mental health, is needed to strengthen HIV prevention in West African MSM.