The Parkinson's disease symptom inventory (PDSI): a comprehensive and sensitive instrument to measure disease symptoms and treatment side-effects

Parkinson's disease (PD) is associated with an array of signs and symptoms and motor fluctuations. In addition, treatments such as levodopa and dopami ne agonists are associated with side-effects that impact the same health do mains as disease symptomatology. To comprehensively and sensitively assess drug therapies in respect of disease symptoms and side-effects, we designed the Parkinson's disease symptom inventory (PDSI). The PDSI consists of 51 symptoms items identified through expert opinion, patient interviews, and t he medical literature. Items represent a detailed array of motor, postural, muscular, gastro-intestinal, emotional, and cognitive domains. Subjects ar e asked to report the frequency with which each symptom is experienced, as well as the associated subjective distress. After initial elimination of 8 items that did not meet retention criteria, psychometric analysis showed ex cellent internal consistency (alpha = 0.92-0.95) and acceptable reproducibi lity (ICC = 0.72-0.79) of items, Comparison of results with the Unified Par kinson's disease rating scale (UPDRS) and the Parkinson's impact scale (PIM S) revealed correlation with the PDSI, with Pearson's r values of roughly 0 .5 and 0.7, respectively. The PDSI demonstrated power to discriminate mean scores of patients comprising the highest and lowest tertiles of the UPDRS and PIMS instruments. In summary, the PDSI demonstrated good psychometric p erformance characteristics, and may yield valuable data regarding the compa rative effectiveness of PD therapies. (C) 1999 Published by Elsevier Scienc e Ltd. All rights reserved.