Introduction Men who have sex with men (MSM) constitute a risk group for sexual transmitted infections (STIs), including HIV. Despite counselling interventions, risk behaviour remains high. Syndemic theory holds that psychosocial problems often co-occur, interact and mutually reinforce each other, thereby increasing high risk behaviours and co-occurring diseases. Therefore, if co-occurring psychosocial problems were assessed and treated simultaneously, this might decrease high risk behaviour and disease.

Method An open label randomised controlled trial will be conducted among 150 MSM with high risk behaviour recruited from the STI clinic of Amsterdam. Inclusion criteria are: HIV negative MSM with two STI or PEP treatment in the last 24 months or HIV positive MSM with one STI in the last 24 months. All participants get questionnaires on the following syndemic domains: ADHD (ASRS), depression (HADS), anxiety disorder(HADS), alexithymia (TAS) and sex(SCS, Kalichman) and drug addiction(DUDIT and AUDIT). Participants in the control group receive standard care for one year: STI screenings every three months and motivational interviewing based counselling. Participants in the experimental group receive standard care plus additional questionnaires depending on baseline questionnaire scores followed by feedback and referral to a co-located mental health or addiction service in case of a positive indication according to the additional questionnaires. The primary outcome is help seeking behaviour for mental health problems and/or drug use problems. The secondary outcomes are STI incidence and changes in sexual risk behaviour (i.e. condom use, number of anal sex partners, drug use during sex).

Conclusion This study will provide information on syndemic domains among MSM who show high risk behaviour and on the effect of screening and referral on help seeking behaviour and health (behaviour) outcomes. Inclusion started in September 2016, on 1 December more than 60 MSM were included with this pace baseline data will be available in July 2017.