Objectives: To verify if sexual behavior, use of contraceptive methods and the hygienic personal habits affect the risk for urinary tract infection (UTI) in sexually active women.

Design: Case-control study.

Setting: Internal Medicine Outpatient Department of a tertiary-care hospital.

Patients: Sexually active females in the age range from 16 to 50 years, attended in an unity of the Internal Medicine Outpatient Department, from March to July 1998.

The cases: 125 women attended due to urinary complaints and with UTI confirmed by urine culture.

The controls: 375 women attended without urinary complaints and negative urine culture.

Methods: A questionnaire about many topics of possible risk factors for urinary tract infection and eventual exposures regarded important in the determination of such infection, as personal hygienic habits, use of contraceptive methods and sexual behavior, was applied. The sample size was calculated to detect an odds ratio of 2 in a relation of 1 case for 3 controls, assuming a type I error (a) of 5% and a statistical power of 80% (b=0.20). The proportion of exposed controls was estimated in 20% with a confidence interval of 95%. The statistical procedures used were: descriptive measurements, frequency tables, multiple correspondence analysis and logistic regression.

Results: From the 500 interviewed women, 125 (25%) presented with UTI. The most frequent germ found was Escherichia coli (80%). Cases and controls were similar concerning age group. The mean for the control group was 33.9 ± 9.6 (SD) and 32.1 ± 9.4 (SD) years for the cases. Multiple correspondence analysis applied to the data showed that both, cases and controls, presented a homogenous pattern for sexual behavior and hygienic habits. Logistic regression analysis applied after the correspondence analysis results, showed that the studied variables are not potential risk factors for UTI in the analyzed population.

Conclusions: The analyzed risk factors (sexual behavior and personal hygienic habits) did not affect the risk for UTI in sexually active women in the age range from 16 to 50 years in the analyzed population.