Botulinum toxin type A injection for refractory interstitial cystitis: A randomized comparative study and predictors of treatment response

Objectives To determine whether botulinum toxin type A can represent an alternative treatment option for patients with interstitial cystitis refractory to conventional therapies. Methods This is a single-center, prospective, open labeled, randomized comparative study. Patients with refractory interstitial cystitis were randomly divided into two groups: immediate injection (group A) or 1-month delayed injection (group B) of botulinum toxin type A after allocation. The rate of treatment response (global response assessment ≥+1: slightly improved), and changes in symptom scores and frequency volume chart variables were compared between groups 1 month after allocation. Using subjects of both groups as a single cohort, predictive factors for treatment response at 1 month post-injection and the duration of response were explored. Results A total of 34 patients (group A n = 18, group B n = 16) were allocated. The response rate was significantly higher in group A than group B (72.2% vs 25.0%, P = 0.01). All symptom measures showed significant improvement in group A than group B. When both groups were combined as a single cohort, the response rate was 73.5% at 1 month, 58.8% at 3 months, 38.2% at 6 months and 20.6% at 12 months. The mean duration of response was 5.4 months. Multivariate analysis showed that past exposure to hydrodistension more than three times correlated with better outcomes. Conclusions Botulinum toxin type A injection could be an alternative treatment option for patients with interstitial cystitis refractory to conventional therapies, especially for those who have received repeated hydrodistensions and transurethral fulguration.