Introduction Sexual behaviour changes during a person’s life course. Insights in sexual careers of men who have sex with men (MSM) may optimise timing of HIV prevention methods. Our objectives were to develop a behavioural risk score for HIV seroconversion and study trajectories of sexual behaviour over time.

Methods Longitudinal data from the Amsterdam Cohort Studies on HIV and AIDS (ACS) were used. We included HIV-negative MSM who visited the ACS at least once between May 2007 and April 2016 (n=820). MSM were bi-annually tested for HIV and completed a questionnaire about their sexual behaviour in the preceding six months. The following behavioural variables were selected a priori: number of casual partners with insertive or receptive anal intercourse (AI), condom use during AI, number of condomless AI partners with unknown or positive HIV status, and AI during group sex. Using Poisson regression, we calculated a risk score for HIV seroconversion. This score was used in growth mixture modelling to examine trajectories of sexual behaviour since first male sexual contact.

Results During follow-up 49 MSM seroconverted. Predictors of seroconversion in multivariable analyses were number of casual partners with receptive AI (log transformed IRR: 1.63, 95% CI: 1.20–2.22) and number of condomless insertive AI partners with unknown or positive HIV status (log transformed IRR: 1.73, 95% CI: 1.24–2.42). We identified 3 sexual risk behaviour trajectories: Decreasing high risk (7% of MSM) with high risk behaviour at start of sexual career and decreasing risk over time; Increasing high risk (3%) with low risk behaviour at start of sexual career and increasing risk over time; and Low risk (90%) with relatively low risk throughout the career. MSM in the decreasing high risk trajectory were younger at first sexual contact than MSM in the Low risk trajectory.

Conclusion We identified 3 distinct sexual career trajectories. Increasing risk behaviour during the life course was found in a small group of MSM. The trajectories of these men might provide clues for time-tailored interventions.