Background The participation of women in prospective sexual health research is key to understanding mechanisms of their health, and best practices need to be shared. We here evaluate participation, retention, and associated factors, of women in a multicenter prospective cohort (FemCure) providing insights in internal and external validity of this prospective study.

Methods Chlamydia trachomatis (CT) infected adult women, negative for HIV, syphilis and Neisseria gonorrhoeae were eligible to be pre-selected and included at three sexually transmitted infection (STI) clinics in The Netherlands (2016–2017). The planned follow-up for participants was 3 months with 2-weekly rectal and vaginal CT self-sampling and online questionnaires at home and at the clinic. We aimed to optimize participation by simultaneously implementing a mix of strategies (e.g. research in an existing clinical infrastructure, incentives, easy data collection, text message reminders). We calculated proportions of women pre-selected, included and retained (completed follow-up). Associations with non-pre-selection, non-inclusion and non-retention (attrition) were assessed (using logistic and Cox regression).

Results Of 4916 women attending the clinics, 1763 (35.9%) were pre-selected, of whom 560 (31.8%) were included. Study site, non-Western migration background, high education, and no STI history were associated with non-pre-selection and non-inclusion. Self-reported reasons for non-inclusion were: unable to attend clinic, language-barriers, or too much expected effort. Retention was 76.3% (n=427). Attrition was 10.71/100 person-months (95% confidence-interval 9.97, 12.69). Women who withdrew felt incapable or unwilling to invest more time. Attrition was associated with young age and low education. Retained women expressed a high study satisfaction.

Conclusion In an outpatient clinical setting, it proved feasible to include and retain women in an intensive prospective cohort with moderate (3 months) follow-up time. External validity may be limited as the study population was not representative (sampling-bias), but this need not affect internal validity. Selective attrition however (potential selection-bias) should be accounted for when interpreting the study-results.

Disclosure No significant relationships.