There are limited data on the impact of the published guidelines of Parkinson's diseases (PD) on clinical practice.

Our aim was to evaluate the impact of clinical guidelines regarding PD by comparing the choice of first anti-Parkinson drug (APD) treatment in PD in two different years.

Two cohorts of PD incident outpatients, diagnosed during 2005 (n=1436) and 2012 (n=1607), were identified from a Finnish nationwide register of special reimbursements for medication costs. Data on their APD drug purchases (ATC codes N04) were obtained from the national prescription register.

Overall, levodopa (LD) monotherapy was the most common initial drug in PD and it was started in more than 80% of the cases aged≥75years. Dopamine agonists (DAs) and monoamine oxidase–B (MAO-B) inhibitors predominated in patients aged<60years and the frequency of both drug classes decreased with advancing age. Significant changes in the prescription pattern occurred after the guidelines were issued, from the year 2005 to 2012 (P=0.002). The use of MAO-B inhibitors increased in patients aged less than 75years. The use of LD decreased in patients aged 64–74years while that of DAs increased.

The choice of first APD drug in PD shows significant age- and time-period-related variation. The prescription patterns for the first APD drug in PD in Finland seem to be in accordance with the principles of the national and international guidelines.