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Effect of the Severity of Incontinence on the Efficacy of Oxybutynin Chloride Topical Gel (OTG) in Improving Continence
Peter K. Sand, MD1, Scott A. MacDiarmid, MD2, Heather Thomas, PhD3, Kim E. Caramelli, MS3, Gary Hoel, PhD3.
1University of Chicago, Pritzker School of Medicine, Chicago, IL, USA, 2Alliance Urology Specialists, Greensboro, NC, USA, 3Watson Laboratories, Inc., Salt Lake City, UT, USA.

Background: Oxybutynin chloride topical gel (OTG), approved for the treatment of overactive bladder (OAB), significantly reduced the number of daily incontinence episodes (IEs), compared with placebo, in a 12-week, double-blind phase 3 study. A post hoc analysis of the phase 3 study data evaluated the effect of incontinence severity on the efficacy of OTG in improving continence.
Methods: Patients were stratified into 2 groups by number of baseline IEs/day (2 to 3 or >3). Assessed were absolute and percentage changes in IEs/day from baseline to the last observation (study end), and the portion of patients who achieved complete continence.
Results: Of the study participants, 171 had 2 to 3 IEs/day, and 556 had >3 IEs/day. Absolute changes in the number of daily IEs from baseline to study end were dependent on baseline IE in both the OTG and placebo treatment groups (Table), but differences in mean change from baseline between treatment groups were similar for both subgroups. Relative IE improvement (OTG vs placebo) was statistically significant in both groups. The percentage of patients who achieved complete continence with OTG was 48% (placebo, 24%) among those with 2 to 3 IEs, and 18% (placebo, 12%) among those with >3 IEs at baseline.
Conclusions: Treatment with OTG resulted in statistically significant and clinically meaningful improvement in continence, irrespective of the severity of incontinence at baseline. Reduction in the absolute number of incontinence episodes with OTG vs placebo appeared to be independent of the severity of incontinence.
Research funded by Watson Laboratories, Inc.

Baseline IEs/day = 2 to 3Baseline IEs/day >3
Mean±SDOTGPlaceboOTGPlacebo
(n=85)(n=86)(n=276)(n=280)
Absolute Change-1.7±1.4-1.2±1.3-3.6±3.0-3.1±3.4
(analysis of covariance)P=.005P=.004
Relative Change, %-69±55-49±49-57±41-47±43
(analysis of variance)P=.015P=.006

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