Rankin scale as a potential measure of global disability in early Parkinson's disease

We conducted an exploratory analysis of the utility of the modified Rankin Scale (mRS) as a global measure of disability in early Parkinson's diesase (PD) using the baseline data from a large cohort of PD patients enrolled in a longitudinal study of creatine. The mRS is scored 0-6 with lower scores reflecting less disability. For the analysis the mRS score was dichotomized at <2 versus >= 2. We explored the association of the mRS with multiple measures of PD-related impairments, including the Unified Parkinson Disease Rating Scale (UPDRS); cognitive function characterized by the Symbol Digit Modalities - verbal, and Scales for Outcomes in Parkinson's disease - cognition (SCOPA-COG); quality of life (Parkinson's disease questionnaire [PDQ-39]) and EuroQOL; Beck Depression Inventory II (BDI); and Total Functional Capacity (TFC). We also investigated the interaction between variables. One thousand seven hundred forty-one patients were included in the analysis of which 374 had a mRS score of 2 or above. In the univariate model, all interested measures except SCOPA-COG (p = 0.23) had significant association with mRS (p < 0.001) after controlling for confounders. In the multivariate model, UPDRS Part II and III (activities of daily living and motor), BDI, TFC and PDQ-39 were significant (p < 0.05). The mRS has a significant association with the wide spectrum of measures of impairment and quality of life in early PD and shows good potential to be a global measure of disability in early PD. The sensitivity of the mRS to change and performance of the scale in more advanced PD will have to be established longitudinally. (C) 2013 Elsevier Ltd. All rights reserved.