A randomized controlled trial of intravesical bacillus Calmette-Guerin for treatment refractory interstitial cystitis

Purpose: We compared intravesical bacillus Calmette-Guerin (BCG) to placebo instillations in patients with treatment refractory interstitial cystitis (IC). Materials and Methods: Subjects who met the National Institutes of Health-National Institute for Diabetes and Digestive and Kidney Diseases criteria for IC, and reported at least moderate pain and frequency for a minimum of 6 months before study entry, were randomized to 6 weekly double-blinded intravesical instillations of either BCG or placebo, and then followed for a total of 34 weeks. The primary outcome was a patient reported global response assessment at week 34, supplemented with medications for IC during weeks 31 to 34. Secondary outcomes included a 24-hour voiding diary, pain, urgency, validated IC symptom indexes and adverse events. The target sample size was 260 participants, designed to detect a difference in response rates between placebo and BCG of 30% and 50%, respectively. Results: A total of 265 participants were randomized and 17 (6%) patients withdrew from study. The response rates for the primary outcome were 12% for placebo and 21% for BCG (p = 0.062). Small improvements were observed for all secondary outcomes, some more so with BCG, but these differences were of borderline statistical significance. Although a large number of adverse events were reported in the BCG arm, there was no statistically significant difference between the treatment arms in overall adverse event rates. Conclusions: Although the BCG safety profile was acceptable, the response rate for the primary outcome was low. Effective medical treatment for patients with moderate to severe interstitial cystitis remains elusive.