Comparative Persistence, Switch Rates, and Predictors for Discontinuation of Antimuscarinics for Overactive Bladder

Abstract

Objectives: Although antimuscarinic drugs are considered the gold standard for overactive bladder (OAB), high discontinuation rates have been observed. However, no information is known about this in Taiwan. We investigated the persistence and switch rates among different antimuscarinics prescribed for OAB and evaluated whether different comorbidities impacted the persistence with prescribed antimuscarinics in Taiwan. Materials and Methods: We obtained retrospective claims from a Taiwanese health insurance database for patients with OAB; any first claim for the target drugs (tolterodine extended release [ER], tolterodine immediate release [IR], oxybutynin ER, oxybutynin IR, solifenacin, propiverine, and flavoxate) between January 2004 and December 2013 was included. The prescription claims were tracked for 1 year to calculate the time of persistence and switch rates. Comorbidities, including hypertension, diabetes mellitus, and hyperlipidemia, were recorded. Significant factors for discontinuation were investigated by using a Cox proportional hazards model. Results: A total of 24,381 patients with OAB were prescribed the target antimuscarinics. The most prescribed drug during the 10-year period was flavoxate (8339 patients). Of the 3481 patients with chronic OAB, the drug with the longest mean persistence was solifenacin (125 days). At 12 months, the persistence rate varied from 7.6% for oxybutynin ER to 4.3% for propiverine. The switch rates varied from 40.3% for propiverine to 25.7% for solifenacin. The Cox proportional hazards model showed that hyperlipidemia was the only comorbidity significantly associated with discontinuation (hazards ratio: 1.12, 95% confidence interval: 1.03–1.21, P = 0.006). Conclusions: In this large nationwide Taiwanese study, 12-month persistence was generally low for all antimuscarinics. Solifenacin was associated with the longest mean persistence and the lowest switch rates, oxybutynin ER had the highest 12-month persistence rate, and hyperlipidemia was significantly associated with lower persistence.