The O'Leary‐Sant Interstitial Cystitis Symptom Index is a clinically useful indicator of treatment outcome in patients with interstitial cystitis/bladder pain syndrome with Hunner lesions: A post hoc analysis of the Japanese phase III trial of KRP‐116D, 50% dimethyl sulfoxide solution

OBJECTIVES: To evaluate the efficacy of intravesical KRP‐116D, 50% dimethyl sulfoxide solution, in interstitial cystitis/bladder pain syndrome patients with Hunner lesions (Hunner‐type interstitial cystitis), and to evaluate the correlations between efficacy variables and global response assessment to determine what constitutes a minimal clinically important change. METHODS: We performed a post hoc analysis of the Japanese phase III trial of KRP‐116D. Changes at Week 12 from baseline in objective and subjective outcomes were compared between the KRP‐116D and placebo groups in Hunner‐type interstitial cystitis or non‐Hunner‐type interstitial cystitis patients. Correlations between efficacy variables at Week 12 and global response assessment were analyzed. Area under the receiver operating characteristic curve and the cut‐off value of efficacy valuables were calculated to determine clinically meaningful changes. RESULTS: The effectiveness of intravesical treatment with KRP‐116D was demonstrated in Hunner‐type interstitial cystitis, but not in non‐Hunner‐type interstitial cystitis patients. Global response assessment was closely correlated with subjective outcomes including O’Leary‐Sant Interstitial Cystitis Symptom Index, O’Leary‐Sant Interstitial Cystitis Problem Index, and a numeric rating scale for bladder pain, but was less correlated with voiding variables including micturition frequency, voided volume, and maximum voided volume. In the receiver operating characteristic curve analyses, the cut‐off value for the O’Leary‐Sant Interstitial Cystitis Symptom Index was −5 (sensitivity 81.3%, specificity 83.3%). CONCLUSIONS: Clinical benefit of intravesical KRP‐116D in Hunner‐type interstitial cystitis patients was confirmed in this post hoc analysis. A five‐point reduction in O’Leary‐Sant Interstitial Cystitis Symptom Index is a clinically meaningful indicator for assessing patient satisfaction with KRP‐116D treatment in patients with Hunner‐type interstitial cystitis.