Background and objectives: The incidence of four STDs that are mainly transmitted during vaginal intercourse, and risk factors for acquisition during follow-up were studied in a cohort of heterosexuals with multiple partners in Amsterdam, the Netherlands. These heterosexuals with > or = 5 different sexual partners in the preceding 6 months were recruited from an STD clinic and participated voluntarily in a longitudinal HIV study between 1987 and 1991.
Study design: Using survival techniques, the authors analyzed data on general characteristics, sexual behavior, reported and diagnosed STDs of 155 men and 234 women participating at least twice in the HIV study and returning regularly.
Results: The majority of women were prostitutes and the majority of men were clients of prostitutes. For men and women, the 2-year cumulative incidence were 2.7% (95% confidence interval [95% CI] 0.9-8.3) and 0.8% (95% CI 0.1-5.8), respectively, for syphilis, 8.5% (95% CI 3.9-18.0) and 5.3% (95% CI 2.6-10.8) for gonorrhea, 20.2% (95% CI 12.5-31.9) and 31.9% (95% CI 23.7-42.2) for Chlamydia trachomatis infection, and 24.5% (95% CI 17.3-34.2) for trichomoniasis (examination in women only). Among men, STD(s) diagnosed at entry was found to be an independent predictor of infection with any of these STDs during follow-up (relative hazard (RH) = 2.58, 95% CI 1.18-5.64). Among women, risk factors were age < or = 25 years (RH = 1.82, 95% CI 1.13-2.19) and current report of commercial unprotected vaginal contacts (RH = 2.19, 95% CI 1.11-4.13). Among women, trichomoniasis during follow-up was predicted by current report of commercial contacts (RH = 2.59, 95% CI 1.16-5.79). C. trachomatis infection in women was associated with native country outside the Netherlands (RH = 2.47, 95% CI 1.38-4.43), reported history of STDs in the 4 months before the study (RH = 2.92, 95% CI 1.39-6.14) and age < or = 25 years (RH = 1.90, 95% CI 1.06-3.40).
Conclusions: This study shows that STDs were common among this group of heterosexuals, despite regularly participating in the HIV study in which consistent condom use was promoted. Prevention efforts should be intensified for men and women having commercial sexual contacts, young women, and individuals with a history of STDs.