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.