Systematic evaluation of rating scales for impairment and disability in Parkinson's disease

We assessed the clinometric characteristics of rating scales used for the evaluation of motor impairment and disabil- ity of patients with Parkinson's disease (PD), conducting a systematic review of PD rating scales published from 1960 to the present. Thirty studies describing clinometrics of 11 rating scales used for PD were identified. Outcome measures included validity (including factor structure), reliability (internal consis- tency, inter-rater, and intrarater) and responsiveness. We traced three impairment scales (Webster, Columbia University Rating Scale (CURS) and Parkinson's Disease Impairment Scale), four disability scales (Schwab and England, Northwestern Univer- sity Disability Scale (NUDS), Intermediate Scale for Assess- ment of PD, and Extensive Disability Scale), and four scales evaluating both impairment and disability (New York Univer- sity, University of California Los Angeles, Unified Parkinson's Disease Rating Scale (UPDRS), and Short Parkinson Evalua- tion Scale). The scales showed large differences in the extent of representation of items related to signs considered responsive to dopaminergic treatment or to those signs that appear late in the disease course and lack responsiveness to treatment. Re- gardless of the scale, there was a conspicuous lack of consis- tency concerning inter-rater reliability of bradykinesia, tremor, and rigidity. Overall disability items displayed moderate to good inter-rater reliability. The available evidence shows that CURS, NUDS, and UPDRS have moderate to good reliability and validity. In contrast to their widespread clinical use for assessment of impairment and disability in PD, the majority of the rating scales have either not been subjected to an extensive clinometric evaluation or have demonstrated clinometric short- comings. The CURS, NUDS, and UPDRS are the most evalu- ated, valid, and reliable scales currently available. © 2002