Feasibility and Research Insights From a Randomized Controlled Trial for Recurrent Urinary Tract Infection Prevention in Postmenopausal Women Using Vaginal Estrogen Therapy

Objective: The aim of the study was to inform feasibility parameters (eligibility, enrollment, and retention) for a recurrent urinary tract infection (rUTI) prevention randomized controlled trial (RCT).

Methods: We assessed feasibility parameters of an RCT of postmenopausal women with uncomplicated rUTIs using vaginal estrogen. Participants were randomized to either d-mannose or a control arm. All participants were required to be using vaginal estrogen and to have a negative urine culture before 90-day trial participation. An RCT exit survey and separate survey for UTI patients (N = 196) were added to inform feasibility parameters and patient preferences for rUTI prevention and study participation after slower enrollment than anticipated.

Results: At the time of interim and subsequent futility analyses, 545 patients had been evaluated for frequent/recurrent UTIs from March 1, 2018, to January 18, 2020. Of these, 213 (39.1%) had culture-proven rUTIs and 71 (33.3% of those with culture-proven rUTIs) were eligible for the RCT. Reasons for ineligibility included complicated UTIs, premenopausal/perimenopausal status, or existing UTI prevention regimen. Of the 71 eligible participants, 57 (80.3%) enrolled, and 44 began their planned 90-day study period (77.2%; 80.0% after excluding 2 participants awaiting negative urine cultures at the time of analysis). The study was halted before conclusion. Study retention (76.0%-83.7%) was slightly lower than expected. Urinary tract infection survey patients demonstrated significant interest in rUTI research participation.

Conclusions: We learned several important lessons that can benefit future research. Many patients with frequent/recurrent UTIs are interested in research, but rigorous eligibility criteria and referral urine culture documentation made recruitment challenging.