BERKELEY, CA (UroToday Inc.) - Urinary tract infections (UTI) are a common problem for many women. The risk factors predisposing to UTI are different for pre and postmenopausal women. Dr. Sara Jackson and colleagues from Seattle, WA and West Haven, CT performed a prospective study to determine the incidence and risk factors for acute cystitis in nondiabetic and diabetic postmenopausal women. Their findings were published in the December 2004 edition of the American Journal of Medicine.

They performed a 2 year prospective study on women aged 55-75 years of age who were postmenopausal. Subjects were enrolled from Group Health Cooperative in Washington state. The women were randomly selected from the general registry, and in order to have a prevalence of about 20% diabetic patients, women were also enrolled from a diabetes registry. Patients were followed for two years with visits at baseline, 12, and 24 months. Demographic, medical, and social information was obtained from the patients. Fasting blood glucose levels were measured. UTI was defined as irritative voiding symptoms and a midstream urine specimen with at least 105 colony-forming units/ml of an uropathic organism. Patients were instructed to contact research personnel for any symptoms suggestive of acute cystitis, which would prompt a standardized interview. Clinical charts were also surveyed to capture episodes of acute cystitis that were unreported to the investigators.

A total of 1017 eligible patients were enrolled in the study. Of these 799 were not diabetic, while 218 were. 87% of the subjects completed the 12 month follow up and 81% completed the 24 month follow-up. 138 symptomatic infections were documented during the study for an incidence of 0.7% per person-year.

Univariate analysis revealed the following risk factors associated with UTI: lower general health score on SF-36 health survey, diabetes and need for insulin, history of renal calculi, four or more full-term pregnancies, vaginal dryness, assymptomatic bacteruria at baseline, recent infection, family history of UTI, life time number of UTI, and use of vaginal estrogen cream.

Age adjusted multivariate analysis revealed the following risk factors: insulin-treated diabetes, use of estrogen cream in the last moth, renal calculi, assymptomatic bacteruria at baseline and lifetime number of urinary tact infections.

Other factors such as sexual activity, postcoital urination, use of cranberry juice, urinary incontinence, and postvoid residual volume were not associated with the incident of UTI.

The strongest risk factors were the lifetime history of UTI and insulin-treated diabetes. Contrary to other studies, in this study the use of vaginal estrogen cream was not helpful in preventing UTI. It appears as though attention to insulin-treated diabetes is a potentially modifiable factor that may decrease the incidence of UTI in postmenopausal women.

Am J Med 2004;117: 903-911