Urodynamic results and clinical outcomes with intradetrusor injections of onabotulinumtoxinA in a randomized, placebo-controlled dose-finding study in idiopathic overactive bladder

Abstract

Aims: We assessed the effects of onabotulinumtoxinA (BOTOX®) on clinical and urodynamic variables in patients with idiopathic overactive bladder (OAB) and urinary urgency incontinence (UUI) with or without detrusor overactivity (DO), inadequately managed with anticholinergics.

Methods: Three hundred thirteen patients with OAB were randomized to double-blind intradetrusor injection with placebo (n = 44) or 1 of 5 onabotulinumtoxinA doses (50-300 U; n = 269). Primary efficacy variable was change from baseline in UUI episodes/week at week 12. Urodynamic assessments at baseline and weeks 12 and 36 included maximum cystometric capacity (MCC) and volume at first involuntary detrusor contraction (IDC).

Results: 76.0% of patients had baseline DO. Changes from baseline in MCC and volume at first IDC with onabotulinumtoxinA ≥100 U were superior to placebo at week 12, generally decreasing by week 36. Significant dose-dependent increases in MCC were observed for all onabotulinumtoxinA doses at week 12, and for 150, 200, and 300 U at week 36. Data suggested a dose-response relationship. At week 12 on diary, 15.9% of placebo and 29.8-57.1% of onabotulinumtoxinA 50-300 U recipients, respectively, did not demonstrate UUI. OnabotulinumtoxinA doses >150 U were more commonly associated with post-void residual urine volumes >200 ml.

Conclusions: Improvements in urodynamic parameters and clinical outcomes generally trended together following onabotulinumtoxinA treatment. This therapy improved key urodynamic parameters in patients with idiopathic OAB and UUI, with no differences in outcomes between those with and those without baseline DO. Therefore, successful idiopathic OAB treatment with onabotulinumtoxinA does not appear to be related to pretreatment finding of DO.