Discontinuation Rates of Anticholinergic Medications Used for the Treatment of Lower Urinary Tract Symptoms

OBJECTIVE: To estimate the discontinuation rates of anticholinergic medications used for the treatment of lower urinary tract symptoms in women. METHODS: A large administrative database was used for this study. Women aged 18 years and older who were prescribed anticholinergic medications were included. An overall and drug-specific discontinuation rate for nine different anticholinergic medications was estimated. Covariates examined included number of prior drug classes used, number of switches performed, number of prior drug episodes, year of initiation, age, and history of smoking. The Kaplan-Meier method was used to estimate an overall discontinuation rate. A Cox multivariable regression was performed for the drug-specific analysis. RESULTS: There were 49,419 episodes of anticholinergic therapy available for analysis from 29,369 women. The average number of treatment episodes and number of drug classes prescribed per patient were 1.65 +/- 1.31 and 1.54 +/- 0.57, respectively. The median time for overall anticholinergic drug discontinuation was 4.76 months. The 6-month unadjusted cumulative incidence of discontinuation was 58.8% (95% confidence interval [CI] 58.4-59.3). The percentage of episodes in which women switched to another medication was 15.8% (95% CI 15.4-16.1). At 6 months, the adjusted cumulative incidence of discontinuation was as follows: oxybutynin 71% (95% CI 68.4-73.5), tolterodine tartrate 61% (59.4,64.3), extended-release oxybutynin 57% (95% CI 55.1-59.4), and extended-release tolterodine tartrate 54% (95% CI 52.3-57.7). CONCLUSION: Discontinuation rates for anticholinergic medications are high regardless of the class of medication used.