Condom effectiveness against non-viral STIs: Findings from a multisite prospective study

Objectives: To prospectively evaluate the protective value of consistent and correct use of latex condoms against the acquisition of Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis. Methods: Patients (N=929) attending clinics that diagnose and treat sexually transmitted infections (STIs) were recruited and prospectively followed for up to six months. Evaluation for the three pathogens was conducted by urine nucleic acid amplification testing at baseline, three months, and six months. Participants were instructed to respond to daily prompts, delivered by a hand-held device, by completing a report regarding condom use with each penile-vaginal sexual intercourse event. Generalized Estimation Equations models examined associations between consistent as well as consistent and correct condom use and STI incidence over the 3-month intervals, controlling for age, gender, and history of STIs. Results: Participants reported a total of 14,970 penile-vaginal sex events, of which 9,545 (63.8%) involved use of a condom. Of the sex events involving a condom, 2,285 (23.9%) included one or more condom use errors or problems, leaving 7,260 events where condoms were used correctly. Consistent condom use was not significantly associated with STI incidence (Estimated Odds Ratio [EOR]=.75; 95% CI=.43-1.30; P=.31). However, significant differences were observed when accounting for correct use. Participants who used condoms both correctly and consistently were estimated to have 56% lower odds of acquiring an STI (EOR=.44; 95% CI=.20-.94; P=.03) compared to those not reporting consistent and correct use. Conclusions: The correct as well as consistent use of condoms greatly reduces the odds of non-viral STI acquisition.