Sexual intercourse and risk of symptomatic urinary tract infection in post-menopausal women

BACKGROUND: Sexual intercourse increases the risk of symptomatic urinary tract infections (UTI) in young women, but its role among post-menopausal women is unclear. OBJECTIVE: To determine whether recent sexual intercourse, as documented by daily diaries, is associated with an increased risk of symptomatic UTI in post-menopausal women. DESIGN: A 2-year prospective cohort study conducted from 1998 to 2002. PARTICIPANTS: One thousand and seventeen randomly selected post-menopausal women enrolled at Group Health Cooperative (GHC), a Washington State HMO. MEASUREMENTS AND MAIN RESULTS: Women were asked to enter daily diary information on vaginal intercourse, medication use, and genito-urinary symptoms. The outcome of interest, symptomatic UTI, was defined as a positive urine culture >= 10(5) CFU/mL of a uropathogen and the presence of >= 2 acute urinary symptoms. Nine hundred thirteen women returned diaries and were included in this study. Seventy-eight women experienced 108 symptomatic UTIs, and 361 (40%) reported sexual intercourse in their diaries. There was an increased hazard for UTI 2 calendar days after the reporting of sexual intercourse in the diaries (adjusted hazard ratio [HR], 3.42, 95% CI 1.49-7.80), while there was no evidence for an increased hazard associated with intercourse at other times. When the UTI criterion was relaxed from >= 10(5) CFU/mL to >= 10(4) CFU/mL, adding 9 UTI events to the analysis, the HR for UTI 2 days after intercourse changed slightly to 3.26 (95% CI 1.43-7.43). CONCLUSIONS: Our data suggest that, as with younger women, recent sexual intercourse is strongly associated with incident UTI in generally healthy post-menopausal women.