Introduction

Antimuscarinic are the current pharmacological mainstay for overactive bladder (OAB). However, adverse events resulting from antimuscarinics are inevitable in some patients. Discontinuation rates of 70% to 90% within the first year of therapy have been reported for various OAB medications, because the therapy did not produce the treatment bene?t expected. Mirabegron, which acts as a subtype of relaxation of detrusor, appeared on the Japanese market in 2011, and it provides a new treatment option for OAB. Currently, there are few published studies on the long-term persistence with drug therapy among OAB patients. The purposes of this study were to evaluate OAB pharmacotherapy adherence.

Methods

Patients 18 years of age or older who received an OAB diagnosis and OAB medication prescription for one ?3-adrenoceptor and six antimuscarinics were identified from April 2013 to August 2016. The study cohort consisted of 1,917 OAB patients in Aichi Medical University Hospital. Medication status such as persistence, switching, adherence and the reasons for discontinuation were examined. Persistence was measured by the length of continuous medication with OAB drugs. Time to discontinuation was defined as the number of days between the first dispense date and the expected end date of the last refill. The cumulative incidence of medication persistence was estimated using Kaplan-Meier method. Patients who remained on treatment until the end of the follow-up were regarded as censored data, and the length of follow-up period was assigned as the time of persistence. The proportion of persistence was compared according to each drug using the log-rank test.

Results

The mean patient age and time of persistence were 72.0 years and 323.9 days, and the following drugs were prescribed to OAB patients for 245 of imidafenacin, 24 of oxybutynin, 747 of solifenacin, 17 of tolterodine, 67 of fesoterodine, 100 of propiverine hydrochloride, and 723 of mirabegron. The 1-year persistence rate of each drug were 31.6%, 17.4%, 35.9%, 12.5%, 21.9%, 36.5% and 41.7%, respectively. The median of time to discontinuation were 184 days, 112 days, 196 days, 182 days, 77 days, 189 days and 231 days, respectively. Patients taking mirabegron demonstrated statistically significantly greater adherence than those taking antimuscarinics in both sexes.

Conclusions

Mirabegron was associated with higher levels of persistence and adherence than antimuscarinics in our large and long term cohort.

Funding

none