Evaluation of systemic estrogen for preventing urinary tract infections in postmenopausal women

Abstract Importance: Current guidelines for postmenopausal recurrent urinary tract infection (rUTI) prevention recommend the use of vaginal topical estrogen products but not systemic estrogens. Studies show that vaginal estrogen decreases the risk of rUTI, but evidence against use of systemic estrogen is less convincing. Objective: We performed a comprehensive literature review to evaluate the effect of systemic estrogen on UTI occurrence among postmenopausal women. Evidence Review: MEDLINE (PubMed), EMBASE, and CINAHL were searched for manuscripts published in English between January 1990 and July 2020. The search terms were “urinary tract infection” and “estrogen.” Inclusion criteria were studies of postmenopausal women who received systemic estrogen therapy (any regimen) that reported UTI frequency during any follow-up period. Case studies, commentaries, and reviews were excluded. A priori specifications of seven study criteria were set representing the ideal study for assessing efficacy of systemic estrogen for rUTI prevention and were used to evaluate each included study. Findings: Searches identified 281 results, and after deduplication and review, 8 studies met inclusion criteria: 4 randomized controlled trials, 1 secondary analysis of a randomized controlled trial, 1 prospective cohort study, 1 case-control study, and 1 cross-sectional study. Of the eight included studies, only two enrolled postmenopausal women with a rUTI diagnosis, four had sufficient sample size to detect a clinically meaningful difference between systemic estrogen versus placebo, two used dosage regimens anticipated to achieve a therapeutic effect, and three assessed UTI rates for an adequate duration of 6 months or more (the standard minimum duration of time needed to make a diagnosis of rUTI). Overall, none of the studies met all predefined criteria for the ideal study to assess the efficacy of systemic estrogen for rUTI prevention. Conclusions and Relevance: UTIs will continue to be a significant cause of morbidity and hospitalizations in postmenopausal women unless more research is done to better understand the role of estrogen on UTI rates. The evidence arguing use (or abandonment) of systemic estrogen for the prevention of rUTI is based on few studies with substantial methodologic limitations; there is significant room for improvement.