Incident Trichomonas vaginalis Is Associated With Partnership Concurrency: A Longitudinal Cohort Study.

BACKGROUND: Sexual partner concurrency (PC) has been shown to be a risk factor for a number of sexually transmitted infections but it is unknown if it is a risk factor for Trichomonas vaginalis (TV). OBJECTIVE: We assess if there is an association between PC and incident TV infection. STUDY DESIGN: We used mixed effects logistic regression to assess the association between PC and incident TV in the Longitudinal Study of Vaginal Flora, a cohort study of 3620 women followed quarterly for 5 visits. RESULTS: Trichomonas vaginalis was more common in those reporting definite/possible/unknown PC (15.6%/15.0%/18.3%) than those reporting no PC (5.2%; P < 0.001 for all 3 comparisons). After controlling for a range of confounders, incident TV remained associated with reporting that one's partner definitely (adjusted odds ratio, 5.4; 95% confidence interval, 3.7-8.0) and possibly (adjusted odds ratio, 3.4; 95% confidence interval, 2.2-5.1) engaged in PC in the preceding period. CONCLUSIONS: Partner concurrency was associated with incident TV infection.