Psychometric properties of the Unified Parkinson's Disease Rating Scale and of the Short Parkinson's Evaluation Scale.

The internal consistency (Cronbach's alpha and item-total correlation) and construct validity (factor analysis, intercorrelations, and relationship with Hoehn and Yahr staging and Schwab and England's ADL scale) of the sections "motor examination" and "activities of daily living" of the Unified Parkinson's Disease Rating Scale (UPDRS) and of the Short Parkinson's Evaluation Scale (SPES) were analyzed in 59 subjects with Parkinson's disease (PD) with various degrees of disability. Our results indicate that the SPES is easier and quicker than UPDRS and that it maintains many psychometric properties similar to those of the UPDRS, but with the reduction of a number of items and ordinal levels of each item studied here (producing more homogenous sections than the original versions). The tremor items would be better represented as a separate section in both scales.