Adherence, Persistence and Switch Rates for Anticholinergic Drugs Used for Overactive Bladder in Women: Data from the Norwegian Prescription Database

Objective: To investigate the pattern of use of anticholinergic drugs for overactive bladder among women in Norway with regard to persistence, adherence and switch rates.

Design: Observational study.

Setting And Sample: Data from the Norwegian Prescription Database on prescriptions for tolterodine, solifenacin, darifenacin and fesoterodine filled in Norwegian pharmacies from 1 January 2004 to 31 December 2010.

Methods And Main Outcome Measures: Data from the database were analysed at an individual level, and drug persistence, discontinuation rates and switch rates during a follow-up period of 365 days after the first prescription were calculated.

Results: Overall 1-year persistence for new users was 38.0%. Within the same period, a total of 10.3% switched from the index drug to another drug in the same group, whereas 51.7% discontinued without switching. Users of solifenacin and tolterodine were somewhat more persistent than users of darifenacin and fesoterodine. Persistence was lowest (20.9%) in the age group 18-39 years, increased with age and was highest in the age groups 70-79 years and 80 years and above (43.5 and 43.3%, respectively). In total, 31.9% filled only one prescription of the drug and, of these, only one of four women switched to another drug. The proportion who were adherent during treatment was 60.4%.

Conclusions: The discontinuation rate for anticholinergic drugs for overactive bladder in women is high. The reasons why patients stop using them remain obscure but could be related both to a limited clinical effect and an unacceptable adverse effect burden.