Effectiveness of intravesical ozone in interstitial cystitis by the O'Leary–Sant symptom index

INTRODUCTION AND HYPOTHESIS: A prospective clinical, preliminary study was performed in patients with interstitial cystitis/bladder pain syndrome (IC/BPS) who were nonresponders to conventional treatment and received intravesical ozone as a therapeutic alternative. METHODS: Sixteen patients received six applications of intravesical ozone at a concentration of 41 μg/mL. We evaluated therapeutic efficacy by the percentage reduction of Interstitial Cystitis Symptom and Problem Index scores (ICSI/ICPI—the O'Leary–Sant symptom index), recurrence rate, nonresponse, and side effects in scores collected on admission (pre-treatment), at the end of the therapeutic protocol (post-treatment), and 180 days (follow-up) after the last ozone application. RESULTS: The mean age of women was 52.9 years (SD: 15.5), and the duration of symptoms was 5.7 years (SD: 7.1). The median ICSI on admission was 17 (IQR: 14.25–19.5) and at follow-up was 0.5 (IQR: 0–2), with a reduction of 97.5% (CI: 85.7–100). The median ICSI/ICPI on admission was 31.5 (IQR: 29–35.2) and at follow-up was 2.0 (IQR: 0–3.75), with a reduction of 92.3% (CI: 88.8–100). The recurrence rate was only 6.25%, and no patients were nonresponders to the treatment. CONCLUSIONS: The application of intravesical ozone was effective in the treatment of patients with IC/BPS who were nonresponders to conventional therapy, showing a progressive and safe effect, at least in the short term. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00192-022-05383-3.