Objectives

The objective of this study was to compare efficacy and adverse events between 100 U and 200 U of onabotulinumtoxinA for 6 months in women with nonneurogenic urgency incontinence.

Methods

This is a secondary analysis of 2 multicenter randomized controlled trials assessing efficacy of onabotulinumtoxinA in women with nonneurogenic urgency incontinence; one compared 100 U to anticholinergics and the other 200 U to sacral neuromodulation. Of 307 women who received onabotulinumtoxinA injections, 118 received 100 U, and 189 received 200 U. The primary outcome was mean adjusted change in daily urgency incontinence episodes from baseline over 6 months, measured on monthly bladder diaries. Secondary outcomes included perceived improvement, quality of life, and adverse events. The primary outcome was assessed via a multivariate linear mixed model.

Results

Women receiving 200 U had a lower mean reduction in urgency incontinence episodes by 6 months compared with 100 U (-3.65 vs -4.28 episodes per day; mean difference, 0.63 episodes per day [95% confidence interval (CI), 0.05-1.20]). Women receiving 200 U had lower perceptions of improvement (adjusted odds ratio, 0.32 [95% CI, 0.14-0.75]) and smaller improvement in severity score (adjusted mean difference, 12.0 [95% CI, 5.63-18.37]). Upon subanalysis of only women who were treated with prior anticholinergic medications, these differences between onabotulinumtoxinA doses were no longer statistically significant. There was no statistically significant difference in adverse events in women receiving 200 U (catheterization, 32% vs 23%; adjusted odds ratio, 1.4 [95% CI, 0.8-2.4]; urinary tract infection, 37% vs 27%; adjusted odds ratio, 1.5 [95% CI, 0.9-2.6]).

Conclusions

A higher dose of onabotulinumtoxinA may not directly result in improved outcomes, but rather baseline disease severity may be a more important prediction of outcomes.