The prevalence of Parkinson's disease in British Columbia, Canada, estimated by using drug tracer methodology

Abstract

Objective: To estimate the prevalence of Parkinson's disease (PD) in British Columbia utilizing the prescription database of the College of Pharmacists.

Methods: Patients receiving anti-parkinsonian drug (anti-PD) prescriptions between 1996 and 1998 were stratified by year, age, gender, drug use category, and geographic location. The numbers of patients on levodopa alone, or levodopa and/or other anti-PD drugs were adjusted using published data which gave estimates of the proportion of undiagnosed patients with PD, the proportion of those treated for parkinsonism with definite PD, the proportion of patients with PD not being treated with anti-PD medications, and the proportion of patients treated with anti-PD medications who have PD. Use of the anti-PD drug bromocriptine for other purposes in women under 50 years of age was also considered.

Results: The estimated prevalences of PD based on all anti-PD medications used were 109, 121, and 125 per 100,000 population in 1996, 1997, and 1998, respectively. Estimated prevalences of PD based on levodopa use were 126, 134, and 144, respectively. The prevalence in both prescription groups increased with age. The male to female ratio of prevalence ranged from 1.16 to 1.21.

Conclusions: Using a large, accurate database, it is possible to estimate the prevalence of PD in a large population, though the assumptions built into the estimate remain to be validated in the subject population.