Evaluation of disability in Parkinson's disease. Clinical evaluation and instrumental tests.

To investigate the relationship between instrumental and clinical tests and their validity for the evaluation of disability in Parkinson's disease, we studied 33 patients using three neuropsychological tests for speed and motor evaluation, as well as Yahr's Clinical and the Northwestern University Disability Scales for clinical purposes. Multiple regression analysis revealed that clinical measures explain 30% of disability variance and instrumental tests 34%, although without statistical significance. However, used simultaneously they may account for 98% (p less than 0.02). These results suggest that clinical and instrumental measures are complementary and should be used together in the evaluation of Parkinson's disease.