Cholinesterase Inhibitor Utilization: The Impact of Provincial Drug Policy on Discontinuation.

Background: In October 2007, British Columbia started to cover the cost of cholinesterase inhibitors (ChEIs)-donepezil, galantamine, and rivastigmine-for patients with mild to moderate dementia and prominent Alzheimer's disease.

Objectives: To examine the impact of this policy on persistence with ChEIs.

Methods: A population-based cohort study was conducted using British Columbia administrative health data. We examined 45,537 new ChEI users aged 40 years and older between 2001 and 2012; 20,360 (45%) started the treatment after the coverage policy was launched. Patients were followed until treatment discontinuation, defined as a ChEI-free gap of 90 days, death, or December 2013. Persistence on ChEIs was estimated using survival analysis and competing risk approach. Hazards of discontinuation were compared using competing risk Cox regression with propensity adjustment.

Results: Patients who started ChEI therapy after the introduction of the coverage policy had a significantly longer persistence. Median ChEI persistence until discontinuation or death was 9.37 months (95% confidence interval [CI] 9.0-39.7) and 17.6 months (95% CI 16.9-18.3) in patients who started therapy before and after the new policy, respectively. The propensity-adjusted hazard ratio for discontinuing therapy was 0.91 (95% CI 0.88-0.94). Similar patterns were observed for persistence with the first ChEI (propensity-adjusted hazard ratio of 0.94; 95% CI 0.91-0.98). In rivastigmine users, the hazard ratio was insignificant (0.98; 95% CI 0.92-1.02).

Conclusions: The British Columbia ChEI coverage policy was associated with significantly prolonged persistence with donepezil and galantamine, but not rivastigmine.