A randomized controlled trial of intravesical bacillus calmette-guerin for treatment refractory interstitial cystitis

We compared intravesical bacillus Calmette-Guerin (BCG) to placebo instillations in patients with treatment refractory interstitial cystitis (IC).

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.

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.

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.