Randomized Arms
Arm A · n = 127
Anticholinergic
Solifenacin 5 mg (escalation to 10 mg, then trospium XR 60 mg) + saline injection
Arm B · n = 122
OnabotulinumtoxinA
100 U intradetrusor injection + oral placebo
Double-blind, double-placebo design — participants in the anticholinergic group received saline injection, and participants in the Botox group received oral placebo. After treatment cessation at 6 months, Botox showed longer duration of effect (38% vs 25% adequate control at 12 months).
Primary Outcome: UUI Episode Reduction
−3.4
Anticholinergic
episodes/day reduction
−3.3
OnabotulinumtoxinA
episodes/day reduction
P = 0.81
No significant difference
from baseline avg 5.0/day
Key Secondary Outcomes
Complete All Incontinence Resolution
Adverse Events
Higher with Anticholinergic
Dry mouth: 46% vs 31% (P=0.02)
Constipation: 28% vs 21% (P=0.06)
Higher with OnabotulinumtoxinA
UTI: 33% vs 13% (P<0.001)
Self-catheterization at 2 mo: 12% vs 2% (P=0.002)
PVR >150 mL at 1 mo: 27% vs 5% (P<0.001)
Clinical Bottom Line
Anticholinergic therapy and onabotulinumtoxinA 100 U produce equivalent reductions in UUI episodes, supporting Botox as a reasonable alternative to anticholinergics rather than exclusively a third-line option. The tradeoff: dry mouth (anticholinergics) versus UTI and catheterization risk (Botox). Botox achieves more complete continence (27% vs 13%).