The safety and efficacy of botulinum toxin‐A in the management of bladder oversensitivity: a randomised double‐blind placebo‐controlled trial

Summary Objective:  To assess the safety and efficacy of botulinum toxin‐A (botn‐A) in the management of patients with bladder oversensitivity (BO). Patients and methods:  Twenty‐three consecutive patients with a diagnosis of BO refractory to anticholinergics were enrolled in this randomised, double blind, placebo‐controlled trial. Patients were randomly allocated to receive intradetrusor injections of either botn‐A (100 U Botox ® ) or saline (placebo) via a flexible cystoscopic approach. The study was designed to have 90% power to detect a change in the maximum cystometric capacity (MCC) of 30%. It was calculated that a total cohort of 58 patients would be required. Urodynamic assessment (UDS), voiding diaries (VD) and quality of life (QoL) were assessed at baseline and at 4 and 12 weeks following intervention. Results:  An interim analysis was performed and the trial halted after recruitment of 23 patients as a result of poorly perceived patient benefit. Data were analysed for 21 patients (10 botn‐A; 11 placebo). In the treatment arm, there was a significant increase in MCC (mean rise 105 ml; p = 0.009). However, storage symptoms remained statistically unchanged following botn‐A. Three patients in the treatment arm were required to perform clean intermittent self‐catheterisation with no clinical improvement. The limitations of this trial include the small sample size and the unplanned interim analysis. Conclusions:  This is the first randomised, double blind, placebo‐controlled trial examining the effects of botn‐A exclusively in patients with BO. A significant increase in MCC was observed but this did not translate to clinical benefit with no change observed in the symptoms and quality of life for the majority of patients.