Vaginal estrogen effective against recurrent UTIs

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According to a recent study published in the American Journal of Obstetrics & Gynecology, vaginal estrogen is effective in preventing recurrent urinary tract infections (UTIs) in women with hypoestrogenism.

Over 60% of women are impacted by UTIs in their lives, costing over $2 billion per year in the United States. Breakthrough infections even while on active antibiotic suppression are reported in 70% to 80% of recurrent UTI cases. 

In women with hypoestrogenism, vaginal estrogen is considered the standard care for preventing recurrent UTI. However, the literature supporting vaginal estrogen use in this context is limited to small clinical trials, with the most common cited trial using a form of estrogen not available in the United States.

Investigators conducted a multicenter, retrospective cohort study to evaluate the association between vaginal estrogen and recurrent UTI. The study was conducted within Kaiser Permanente Southern California (KPSC), a large, managed care organization with a laboratory and pharmacy facilities.

Participants included women aged 18 years and older with a recurrent UTI diagnosis and a vaginal estrogen prescription given from January 1, 2009, to December 31, 2019.As vaginal estrogen is often prescribed to patients with vulvovaginal atrophy from estrogen deficiency, patients given vaginal estrogen for recurrent UTIs were considered to behypoestrogenic.

As age or menopause diagnosis restriction were not used in the study, women with other causes of estrogen deficiency such as oophorectomy, breastfeeding, suppression of the hypothalamic-pituitary-ovarian axis, or ovarian insufficiency were also included. Recurrent UTI was defined as 3 or more positive urine cultures within the 12 months before being prescribed vaginal estrogen.

Pharmacy databases were consulted for vaginal estrogen prescription information, with all forms of vaginal estrogen included. Exclusion criteria included not completing the initial vaginal estrogen prescriptions, using vaginal contraceptive hormones, not having continuous KPSC membership in the year before and after the index prescription date, and having a diagnosis which led to exclusion.

UTI frequency in the 12 months after index vaginal estrogen prescription was measured as the primary outcome of the study. A positive urine culture was defined by 1000 colony forming units or more per mL in at least 1 uropathogen. A separation of 14 days between positive urine cultures was used to measure distinct events.

The frequency of postprescription UTIs was measured as the secondary outcome, compared between women adherent and nonadherent to vaginal estrogen application. Adherence was measured using the number of vaginal estrogen refills, with low adherence considered no refills, moderate adherence considered 1 refill, and high adherence considered 2 or more refills.

There were 5638 women in the final analysis, aged a mean 70.4 years. Urinary incontinence was the most common comorbidity in 40.1% of patients, followed by diabetes in 30.8%. An average 3.9 UTI episodes in the year before vaginal estrogen prescription were seen at baseline. This was reduced to 1.8 following the index prescription, decreasing by 51.9%.

An association was found between the magnitude of UTI recurrence reduction and treatment adherence. One or less UTI experience in the 12 months following the index prescription was reported in 55.3% of women, and no UTI experiences in 31.4%. A decrease in the mean UTI frequency was observed across the 12 months.

Overall, these results indicated reduced rates of recurrent UTI following the use of vaginal estrogen. Investigators concluded this study supports the use of vaginal estrogen to treat women with recurrent UTIs.

Reference

Tan-Kim J, Shah NM, Menefee SA. Efficacy of vaginal estrogen for recurrent urinary tract infection prevention in hypoestrogenic women. American Journal of Obstetrics & Gynecology. 2023;229(2):143.E1-143.E9. doi:10.1016/j.ajog.2023.05.002