Predicting motor decline and disability in Parkinson disease - A systematic review

Context: The clinical course of Parkinson disease (PD) varies from patient to patient. A number of studies investigating predictors of prognosis in patients with PD have been performed. Objective: To summarize evidence on predicting the rate of motor decline and increasing disability in early PD. Data Sources: English-language and French-language literature cited in the MEDLINE database (1966-2002). Study Selection: Cohort and case-control studies investigating associations between clinical features and subsequent motor impairment or disability were selected. Data Extraction: Study methods and results were abstracted by a single reviewer. Data Synthesis: The results of 13 studies were summarized qualitatively. Study methods were highly variable, particularly regarding the choice of outcome measure. Baseline motor impairment and cognitive impairment are probable predictors of more rapid motor decline and disability. A lack of tremor at onset and older age both appear to be predictive of increasing disability, but conflicting results exist for their association with the rate of change of motor impairment. Family history of PD does not appear to be prognostically important. The prognostic value of many other factors studied is uncertain owing to conflicting or unconfirmed results. Conclusions: Uncertainty remains about the prognostic importance of many baseline clinical features in PD. Greater baseline impairment, early cognitive disturbance, older age, and lack of tremor at onset appear to be adverse prognostic factors.