Sexually transmitted diseases and sexual behaviour among young Swedish women : a population-based study

Abstract: Most epidemiologic studies of sexually transmitted diseases (STD) are based on patients seeking help or advice at various health care settings. Because many STD:s are subclinical, epidemiologic surveys can be strengthened by a population-based approach.The aims of the present study were to investigate the prevalence and incidence of STDs in a population of young women, and to assess associations between STDs and social background, education, previous genital infections, sexual behaviour, contraceptive use and reproductive experience.All women belonging to the 19-, 21-, 23- and 25-year age cohorts and living in the catchment area of a community health center, were invited by mail to participate in the study. In the presence of the investigator, participants answered a structured questionaire regarding their social background, education, previous genital infections, sexual behaviour, contraceptive use and reproductive experience. A gynecologic examination was performed. Cervical scrapes for human papillomavirus (HPV) DNA, as well as samples for wet smear, cervical pap smear, and Chlamydia trachomatis (CT) culture were taken. The presence of genital warts was noted, and a colposcopy was performed 2-5 minutes after application of 5% acetic acid on the cervix and vulva. Acetowhite changes were then assessed. A serologic test for CT and herpes simplex virus type 2 (HSV-2) antibodies were performed.Of the 816 women available, 611 (75%) participated in the study. One out of four women reported symptoms from the lower genital tract. The most common were itching, followed by discharge and soreness. There was a significant correlation between the womens" complaint of vaginal discharge, and previous CT infection, lack of lactobacilli and the presence of leucocytosis in wet smear. Twenty-two percent of the women were HPV DNA positive and acetowhitening at the cervix was observed in 16% of the women. The sensitivity of detection of HPV infection by acetowhitening of the cervix was 22% (95%CI 18%, 26%), and the specificity was 90% (95% Cl 87%, 93%). C.trachomatis culture positivity was found in 2.7% of the women and the seroprevalence of CT was 24.7 %. Atypical cytology was found in 3.4% of the women and 6.6% was HSV-2 seropositiv. Of the women studied 23.6% reported having had at least one STD previously and the laboratory analysis showed 45.4% to have had at least one STD. Multivariate logistic regression analysis showed that the number of sexual partners, age at first coitus, history of therapeutic abortion, and previous pelvic inflammatory disease (PID) was independently correlated with CT seropositivity. Lifetime number of sexual partners was the only independent risk factor for HPV. Multivariate analysis showed that increasing age, early sexual debut, and a history of spontaneous abortion were independently related to the presence of HSV-2 antibodies. The lifetime number of sexual partners and coitus on first date were independently associated with a previous STD.Conclusion, We found that one out of four women had some kind of lower genital tract complaint, almost every other women had at sometime in their life an STD, and STDs were often asymptomatic. Acetowhitening of the cervix and vulva has low sensitivity, to low to warrant its use as a predictor of subclinical HPV infection. The pattern of risk factors differed between STDs.