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.