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.