Methenamine hippurate compared with trimethoprim for the prevention of recurrent urinary tract infections: a randomized clinical trial.

Abstract

The objective was to find an alternative treatment to a low-dose antibiotic for the prevention of recurrent urinary tract infections (UTI) and to evaluate the difference in rates of reinfection within 1year when treated with methenamine hippurate for prophylaxis compared with trimethoprim. We present a non-blinded randomized trial comparing methenamine hippurate with trimethoprim for the prevention of recurrent UTI at 12months after starting treatment. Women over 18 who had at least two culture-positive UTI in the prior 6months or three in the prior year were included. Ninety-two patients met enrollment criteria and were randomized to receive daily prophylaxis with methenamine hippurate or trimethoprim for a minimum of 6months. Both intent-to-treat and per-protocol analyses if patients received the alternative drug after randomization were analyzed using Student's t test, Mann-Whitney U test, Kaplan-Meier curves, log-rank test, and a logistic and multivariate regression model. The primary outcome of this study was culture-proven UTI recurrence by 12months after initiating prophylaxis. In the intent-to-treat analysis, we found no difference between groups in recurrent UTI, with a 65% (28 out of 43) recurrence in the trimethoprim group versus 65% (28 out of 43) in the methenamine hippurate group (p= 1.00). In the per-protocol analysis, 65% (26 out of 40) versus 65% (30 out of 46) of patients had UTI recurrences in the trimethoprim group versus the methenamine hippurate group (p= 0.98). Methenamine hippurate may be an alternative for the prevention of recurrent UTI, with similar rates of recurrence and adverse effects to trimethoprim.