Risk and course of motor complications in a population-based incident Parkinson's disease cohort

Motor complications may become major challenges in the management of patients with Parkinson's disease. In this study, we sought to determine the incidence, risk factors, evolution, and treatment of motor fluctuations and dyskinesias in a population-representative, incident Parkinson's disease cohort.

In this prospective population-based 5-year longitudinal study, we followed 189 incident and initially drug-naïve Parkinson's disease patients biannually for detailed examination of dyskinesias and motor fluctuations as defined by the Unified Parkinson's disease Rating Scale. We performed Kaplan-Meier survival and Cox regression analyses to assess cumulative incidence and risk factors of these motor complications.

The 5-year cumulative incidence of motor complications was 52.4%. Motor fluctuations occurred in 42.9% and dyskinesias in 24.3%. Besides higher motor severity predicting both motor fluctuations (p = 0.016) and dyskinesias (p < 0.001), lower age at diagnosis predicted motor fluctuations (p = 0.001), whereas female gender predicted dyskinesias (p = 0.001). Actual levodopa dose at onset of motor fluctuations (p = 0.037) or dyskinesias (p < 0.001) rather than initial treatment with levodopa (p > 0.1) independently predicted development of motor complications. Motor fluctuations reversed in 37% and dyskinesias in 49% of patients on oral treatment and remained generally mild in those with persistent complications. No patients received device-aided therapies during the study.

More than 50% in the general Parkinson's disease population develop motor complications within 5 years of diagnosis. However, they remain mild in the vast majority and are reversible in a substantial proportion of patients.