Background: Within a program exploring the safety of antimuscarinic drugs used to treat overactive bladder, we describe use of these drugs.
Objectives: To characterize users and use of darifenacin, fesoterodine, oxybutynin, solifenacin, tolterodine and trospium.
Methods: We followed all persons aged ≥ 18 years with no cancer or HIV and with a prescription for a study drug and no prescriptions for the same drug in the previous year until a cancer outcome, death, disenrollment or end of the study period (2004-2012). We created therapy episodes by concatenating prescriptions, allowing gaps ≤ 60 days. Reasons for ending therapy episodes were drug not refilled, drug added (add-on), or drug switch. We provide descriptive results.
Results: The study cohort had 119,913 persons (70% women, mean age at cohort entry 62 years, mean follow-up 3.3 years); 51% were ever smokers (16% current, missing data 1%); 52% had low/moderate alcohol intake and 18% high (6% unknown amount, missing data 10%). At cohort entry, 81% of subjects had hypertension, 11% diabetes, 13% coronary heart disease, and 3% heart failure. Most subjects entered the cohort with prescriptions for oxybutynin (34%), tolterodine (31%) or solifenacin (28%); fewer were on darifenacin, fesoterodine or trospium. Index therapy episodes were shortest for oxybutynin (mean [SD], 5.5 [10.9] months) and longest for darifenacin (8.9 [14.4] months); 53%-60% of oxybutynin, solifenacin and tolterodine index therapy episodes lasted 1-3 months; 15%-22% continued beyond 9 months. Of study subjects, 73% were exposed to a single drug during follow-up. There were 245,833 therapy episodes (28% oxybutynin, 27% solifenacin, 26% tolterodine, 10% polytherapy). There was no dose change in 88% of therapy episodes. Drugs were not refilled in 89%-92% of oxybutynin, solifenacin or tolterodine episodes; there were add-ons in 8%-11% of the same, and a few switches. Solifenacin was the most common drug added or switched to.
Conclusions: This cohort of OAB drug users comprised mostly elderly females using one drug during follow-up. The observed exposure patterns are well suited to detecting acute adverse events for individual OAB drugs.
