Vaginal estrogen may help prevent UTI recurrence in hypoestrogenic women

The use of vaginal estrogen in women with estrogen deficiency appears to reduce the likelihood of urinary tract infection (UTI) recurring, according to a study.

For the study, researchers reviewed the medical records of 5,638 women (mean age 70.4 years, 59.9 percent White, mean body mass index [BMI] 28.5 kg/m²) who were prescribed vaginal estrogen for the indication of recurrent UTI, which was defined as at least three positive urine cultures (separated by at least 14 days) in the 12 months preceding index vaginal estrogen prescription.

Adherence to treatment was captured through refill data after the index prescription, where no refills indicated low adherence, one refill indicated moderate adherence, two or more refills indicated high adherence.

The majority of the cohort (93.4 percent) was postmenopausal, with mean baseline UTI frequency of 3.9. The mean frequency of UTI episodes in the year following index prescription decreased by 51.9 percent, from 3.9 to 1.8 (p<0.001). Over the 12 months after index prescription, 55.3 percent of the women had not more than one episode of UTI, while 31.4 percent experienced no UTI recurrence.

Factors that predicted UTI recurrence postprescription were age 75–84 years (incident rate ratio [IRR], 1.24, 95 percent confidence interval [CI], 1.05–1.46) and ≥85 years (IRR, 1.41, 95 percent CI, 1.17–1.68), increased baseline urinary tract infection frequency (IRR, 1.22, 95 percent CI, 1.19–1.24), urinary incontinence (IRR, 1.14, 95 percent CI, 1.07–1.21), urinary retention (IRR, 1.21, 95 percent CI, 1.10–1.33), diabetes mellitus (IRR, 1.14, 95 percent CI, 1.07–1.21), and moderate (IRR, 1.32, 95 percent CI, 1.23–1.42) or high medication adherence (IRR, 1.33, 95 percent CI, 1.24–1.42).

Highly adherent women experienced more frequent postprescription UTI episodes compared with low-adherent women (2.2 versus 1.6, p<0.0001).

The paradoxical finding that women with moderate and high adherence experienced the lowest-magnitude reduction in UTI recurrence frequency may be attributed to unobserved selection or unmeasured confounding.