Abstract
OBJECTIVE: In Parkinson disease (PD), the rate of clinical progression is highly variable. To date, there are conflicting findings concerning the prognostic factors influencing the rate of progression. Methodologic issues such as the use of selected patients from therapeutic trials, and short durations of follow-up probably underlie this problem. We therefore designed a prospective follow-up study of a cohort of newly diagnosed patients with PD. METHODS: A cohort of 129 patients with newly diagnosed PD was assessed at baseline, and 1, 2, 3, and 5 years later. The rate of progression and its prognostic factors on the level of motor impairments, disability, and quality of life were investigated using linear mixed-model analysis. RESULTS: Annual increase of motor impairments measured with the Unified Parkinson's Disease Rating Scale-Motor Examination was estimated to be 2.46 points (95% confidence interval: 2.05-2.88). The main determinants of faster increase of motor impairments were male sex and cognitive dysfunction at the time of diagnosis. The main determinants of faster increase of disability were higher age at onset, cognitive dysfunction, and the presence of levodopa-nonresponsive motor symptoms at the time of diagnosis. No clinically relevant determinants were found for the decrease in quality of life. CONCLUSION: This study shows the importance of nondopaminergic symptoms at the time of diagnosis, because these symptoms are the main determinants of increased disability in the first 5 years of the disease.
