Randomized, double-blind, placebo controlled pilot study of intradetrusor injections of onabotulinumtoxina for the treatment of refractory overactive bladder persisting following surgical management of benign prostatic hyperplasia

Introduction: We assessed the efficacy of onabotulinumtoxinA (Botox, Allergan Inc., Irvine, CA, USA) in patients with refractory overactive bladder (OAB) after treatment for benign prostatic hyperplasia (BPH). Materials and methods: This was a two-center, randomized, double-blinded pilot study conducted in patients with OAB secondary to bladder outlet obstruction (BOO), refractory to anticholinergic medication and persistent for greater than 3 months after surgical intervention to relieve obstruction, with an International Prostate Symptom Score (IPSS) > 12. Patients were randomized in 1:1 fashion to either 200 units of onabotulinumtoxinA versus placebo. Fifteen patients received onabotulinumtoxinA versus 13 who received placebo. Follow up was performed at 1 week and then 1, 3, 6, and 9 months. The primary endpoint was reduction in the frequency of micturition per 24 hours by 3-day voiding diary. Secondary endpoints were maximum flow rate (Qmax), post-void residual (PVR), and IPSS scores. Results: Patients receiving onabotulinumtoxinA demonstrated significantly improved quality of life scores at 180 and 270 days after treatment (p = 0.02 and 0.03, respectively) as well as significantly lower International Consultation on Incontinence Questionnaire (ICIQ) scores (p < 0.05). Baseline urinary frequency was 10.5 versus 11.0 voids/day (p = 0.47). Frequency episodes improved from 11 episodes per day to 8 episodes per day in the treatment arm. The placebo arm did not have a decrease in frequency episodes. This response was durable up to 90 days, although this was not statistically significant. IPSS, PVR, and urgency were unchanged postoperatively in both groups. Conclusions: OnabotulinumtoxinA was safe in patients with refractory irritative lower urinary tracts symptoms after surgical treatment of BPH. There were improvements in daily frequency, although the results were not statistically significant. Larger trials are needed to help characterize the utility of onabotulinumtoxinA in the treatment of OAB secondary to BPH.