Introduction: Persistence with antidementia medications at maximum dosages optimises their clinical efficacy. This study assessed the adequacy of dosing and persistence with antidementia medications and the predictors of these variables in the real-world setting.
Methods: The Irish Health Service Executive-PCRS national prescription claims database contains prescription information for 1.6 million people. Patients over 70 years who received at least two prescriptions for donepezil, rivastigmine, galantamine and memantine between January 2006 and December 2010 were included. Rates of dose-maximisation and non-persistence (and predictors of these variables) were analysed.
Results: Between January 2006 and December 2010, 20,729 patients over 70 years received a prescription for an antidementia medication. Rates of non-persistence were 30.1% at 6 and 43.8% at 12 months. Older age (75+ versus <75 years; HR = 1.16, 95% CI: 1.06–1.27) and drug type (rivastigmine versus donepezil; HR = 1.15, 95% CI: 1.03–1.27) increased the risk of non-persistence. Non-persistence was lower for those commencing therapy in more recent years (2010 versus 2007; HR = 0.81, 95% CI: 0.73–0.89) and for those on multiple antidementia medications (HR = 0.59, 95% CI: 0.54–0.65, P < 0.001). Persistence was significantly higher when memantine was co-prescribed with donepezil (P < 0.0001). Despite most patients on donepezil and memantine receiving a prescription for the maximum drug dose, this dose was maintained for two consecutive months in only two-thirds of patients. Patients were significantly more likely to have their doses of donepezil (HR = 2.16, 95% CI: 1.98–2.34, P < 0.001) and memantine (HR = 6.88, 95% CI: 5.35–8.85, P < 0.001) maximised, if prescribed in more recent years.
Conclusion: There is room for improvement in the dosing and persistence with antidementia medications in the community. Strategies should be implemented to overcome this.