Efficacy and safety of onabotulinumtoxinA in patients with overactive bladder: subgroup analyses by sex and by serum prostate-specific antigen levels in men from a randomized controlled trial

PURPOSE: We aimed to assess onabotulinumtoxinA treatment outcomes by sex in patients with overactive bladder (OAB) and then explore the impact of serum prostate-specific antigen (PSA) levels in men. METHODS: Patients inadequately managed with OAB medications were randomized to receive single-dose onabotulinumtoxinA (100 U) or placebo intravesical injection in a phase III trial in Japan. We performed subgroup analyses by sex and post-hoc subgroup analyses using male PSA categories. RESULTS: In women (n = 186), onabotulinumtoxinA demonstrated statistically significant and clinically relevant improvements in all urinary symptoms at Week 12. In men with lower PSA (< 1.5 ng/mL, n = 40), onabotulinumtoxinA also showed numerically greater reductions in urinary symptom frequency than placebo; the between-group differences (onabotulinumtoxinA minus placebo) in change from baseline in the average daily number at Week 12 for urinary incontinence (UI), urgency UI, micturition, urgency, and nocturia were − 1.43, − 1.79, − 2.81, − 2.45, and − 0.32 episodes, respectively. In men with higher PSA (≥ 1.5 ng/mL, n = 22), onabotulinumtoxinA did not reduce urinary symptom frequency. Some patients treated with onabotulinumtoxinA showed elevated post-void residual urine volume at Week 2 (≥ 200 mL): 4 of 91 women, none of the men with lower PSA and 3 of 11 men with higher PSA. CONCLUSIONS: OnabotulinumtoxinA was efficacious and well tolerated in women and in men with lower PSA levels. Given our post-hoc subgroup analyses which suggested that onabotulinumtoxinA treatment is a good treatment option for OAB males with lower PSA levels, future studies having prostate volume data with larger sample size are warranted to verify our findings. CLINICALTRIALS.GOV IDENTIFIER: NCT02820844 (first posted July 1, 2016). https://clinicaltrials.gov/ct2/show/NCT02820844.