A prospective, double-blind, randomized cross-over study evaluating changes in urinary pH for relieving the symptoms of interstitial cystitis

OBJECTIVE: To provide evidence for the clinical efficacy of changes in urinary pH on the pain associated with interstitial cystitis (IC). PATIENTS AND METHODS: A prospective, randomized, double-blind cross-over study was conducted with 26 women with IC between 2000 and 2002, consisting of cross-over instillations of urine at physiological pH (5.0), and neutral buffered pH (NaH2PO4 buffered to pH 7.5). The outcome measured was the subjective symptom of pain assessed using a visual analogue scale at baseline, after the initial instillation of solution, at washout, and after the crossover instillation. Data were analysed using repeated-measures analysis of variance. RESULTS: There was no statistically significant difference between the mean (SD) change from baseline pain scores after instilling neutral buffered solution, at 0.50 (2.78), and acidic solution, at 0.33 (3.43) (P = 0.85). Secondary outcomes were analysed, including baseline variability and treatment-order effects; neither were significantly different between the groups. CONCLUSIONS: There was no statistically significant difference in subjective pain scores on instilling urine at physiological pH or sodium-phosphate buffered saline in these patients with IC. Further work is required to define the role, if any, of urinary pH in the pathophysiology and treatment of IC.