Background: Persistence with antimuscarinic therapy in overactive bladder (OAB) is poor, but may be different for mirabegron, a β₃-adrenoceptor agonist with a different adverse event profile.

Objective: To compare persistence and adherence with mirabegron versus tolterodine extended release (ER) and other antimuscarinics in routine clinical practice over a 12-mo period.

Design, setting, and participants: Retrospective, longitudinal, observational study of anonymised data from the UK Clinical Practice Research Datalink GOLD database. Eligibility: age ≥18 yr, ≥1 prescription for target OAB drug (between May 1, 2013 and June 29, 2014), and 12-mo continuous enrolment before and after the index prescription date.

Interventions: Mirabegron, darifenacin, fesoterodine, flavoxate, oxybutynin ER or immediate-release (IR), propiverine, solifenacin, tolterodine ER or IR, and trospium chloride.

Outcome measurements and statistical analysis: The primary endpoint was persistence (time to discontinuation). Secondary endpoints included 12-mo persistence rates and adherence (assessed using medication possession ratio, MPR). Cox proportional-hazards regression models and logistic regression models adjusted for potential confounding factors were used to compare cohorts. Analyses were repeated after 1:1 matching.

Results and limitations: The study population included 21996 eligible patients. In the unmatched analysis, the median time-to-discontinuation was significantly longer for mirabegron (169 d, interquartile range [IQR] 41-not reached) compared to tolterodine ER (56 d, IQR 28-254; adjusted hazard ratio [HR] 1.55, 95% confidence interval 1.41-1.71; p<0.0001) and other antimuscarinics (range 30-78 d; adjusted HR range 1.24-2.26, p<0.0001 for all comparisons). The 12-mo persistence rates and MPR were also significantly greater with mirabegron than with all the antimuscarinics. Limitations include the retrospective design, use of prescription records to estimate outcomes, and inability to capture reasons for discontinuation.

Conclusions: Persistence and adherence were statistically significantly greater with mirabegron than with tolterodine ER and other antimuscarinics prescribed for OAB in the UK.

Patient summary: This study assessed persistence and adherence (or compliance) with medications prescribed for OAB in a large UK population. We found that patients prescribed mirabegron remained on treatment for longer and showed greater adherence than those prescribed traditional antimuscarinics.