Comparative adherence to oxybutynin or tolterodine among older patients.

Purpose: To compare persistence of oxybutynin or tolterodine therapy among older patients newly prescribed one of these drugs. Methods: We conducted a retrospective cohort study of Ontarians aged 66 years and older who were newly prescribed either drug between January 1, 2000 and December 31, 2007. Persistence with treatment was defined on the basis of refills for the drug within a grace period equal to 50% of the prescription duration. Results: We identified 31,996 patients newly treated with oxybutynin and 24,855 newly treated with tolterodine. After 2 years of follow-up, persistence on oxybutynin (9.4%) was significantly lower than that on tolterodine (13.6%, p < 0.0001). The median time to discontinuation of oxybutynin and tolterodine was 68 and 128 days, respectively. Conclusions: Our findings suggest that the tolerability of these drugs differs substantially. [ABSTRACT FROM AUTHOR]