Learning Curve of Botulinum Toxin Bladder Injection for the Treatment of Refractory Overactive Bladder

PURPOSE: Intradetrusor botulinum toxin injections is an established second-line treatment for patients with refractory overactive bladder syndrome (OAB). We aimed to evaluate the learning curve of intradetrusor injections with botulinum toxin for the treatment of refractory OAB. PATIENTS AND METHODS: This retrospective study analyzed all women with idiopathic and refractory OAB who underwent botulinum toxin bladder injections performed by residents with no previous experience with operative cystoscopy under consultant supervision. Baseline International Consultation on Incontinence Questionnaire-Short Form questionnaire (ICIQ-SF) and Euroqol (EQ-5D) questionnaires were collected. Procedural data (operative time, number of valid injections, complications, subjective easiness, perceived tolerability) and patients’ outcomes (Patients Global Impression of Improvement (PGI-I), ΔICIQ-SF, ΔEQ-5D, need for self intermittent catheterization, duration of efficacy) were considered as markers to evaluate learning curves for each resident. RESULTS: Twenty-seven patients underwent intravesical injection of botulinum toxin performed by residents. Only a grade 1 Clavien-Dindo complication occurred, and none of the patients had urinary retention. PGI-I was very satisfactory, scoring 1.4 ± 0.9. Both ICIQ-SF and EQ-5D 2–2 were statistically improved (p < 0.00001 and p = 0.04, respectively). The mean duration of efficacy resulted to be 8.0±4.3 months. A positive effect of the learning curve was observed only for operative time, subjective easiness, and perceived tolerability. CONCLUSION: Intradetrusor botulinum toxin injection for the treatment of refractory OAB is characterized by high efficacy and very low complications even at the very beginning of the learning curve when performed under proper mentorship.