We compared the number of Parkinsonx2019;s disease cases in British Columbia derived from self-reports in the 2001 Canadian Community Health Survey to those obtained from administrative records of filled levodopa prescriptions and to Parkinsonx2019;s disease diagnoses from physician visit billing and hospital discharge records in 1996 and 2005. We directly compared a case definition based on levodopa prescriptions with a definition based on records of physician diagnosis by calculating positive predictive value and sensitivity.
Crude prevalence estimates ranged from approximately 100 to 200 per 100,000. Levodopa-based case definitions overestimated prevalence, while physician- and hospital-record-based case definitions provided lower prevalence estimates compared to survey derived estimates. The proportion of levodopa users with a diagnosis of Parkinsonx2019;s disease declined from 62 % to 52 % between 1996 and 2005. This decrease was most dramatic among women (64 % x2013;44 % ) and those under age 65 (54 % x2013;39 % ).
Sex and age trends suggest increasing use of levodopa among patients with conditions other than Parkinsonx2019;s disease, such as restless legs syndrome. Increased non-Parkinsonx2019;s levodopa use decreases the efficiency of levodopa as a Parkinsonx2019;s disease case tracer.