Examination of the significant placebo effect in the treatment of interstitial cystitis/bladder pain syndrome.

OBJECTIVE: To examine the significant "placebo effect" in a randomized, double-blind, placebo-controlled interstitial cystitis/bladder pain syndrome trial. Randomized clinical trials are the reference standard for therapeutic impact assessment. However, proving efficacy of treatments for interstitial cystitis/bladder pain syndrome with rigorous placebo-controlled trials is difficult due to a significant effect of the placebo intervention.

METHODS: Interstitial cystitis/bladder pain syndrome patients were randomized to receive subcutaneous adalimumab or subcutaneous placebo every 2 weeks for 12 weeks and outcome measures were assessed.

RESULTS: Of the 43 patients, 21 received adalimumab and 22 received placebo. Of the patients who received placebo, there was a statistically significant improvement demonstrated in the O'Leary-Sant Interstitial Cystitis Symptom and Problem Indexes of -8.1 (95% confidence interval [CI], 3.0-13.2), Interstitial Cystitis Symptom Index of -3.7 (95% CI, 0.9-6.5), Interstitial Cystitis Problem Index of -4.4 (95% CI, 2.0-6.8), and Pelvic Pain, Urgency, Frequency scale of -6.9 (95% CI, 2.8-11.0) at week 12 compared with baseline. Most of the significantly improved placebo patients felt their improvement was because they were more conscientious about following physician advice and feeling less stress while in the study.

CONCLUSION: Patients with moderate to severe interstitial cystitis/bladder pain syndrome had significant improvement after receiving only advice and support. This intervention is risk free and inexpensive. Physicians should review standard advice with all interstitial cystitis/bladder pain syndrome patients before starting medical therapy.