Abstract
The Unified Parkinson's Disease Rating Scale (UPDRS) part III is the principal motor assessment method for Parkinson's disease (PD), but has recognized limitations including subjectivity and insensitivity. Easy to administer, objective, quantitative tests that are good indicators of PD progression could offer advantages in both clinical and research settings. We administered four simple, motor performance measures—functional reach, timed hall walk, a timed block sort task, and timed dotting—as well as the UPDRS to 609 PD patients of a single neurologist. The unadjusted Spearman correlations of these performance measures with the UPDRS motor score (UPDRS III) ranged from 0.29 to 0.49. Moreover, these measures generally had high reliability on repeated testing. We defined specific outcomes in PD—overall disability, gait instability and falls, as well as non-motor outcomes of depression, dementia, and psychosis, and assessed the ability of the measures to predict these outcomes over the entire follow-up of the cohort (average: 2.4 years) and over the first year of follow-up. The associations between the measures and the outcomes were generally stronger and more precise for the performance measures than for the UPDRS III. A summary score of the performance measures was a particularly good predictor of the outcomes. These motor performance measures could provide a rapid, simple means of assessing PD progression that could benefit both clinical and research endeavors.