Barthel Index and modified Rankin Scale: psychometric properties during medication phases in idiopathic Parkinson disease

Abstract Background: Independence in activities of daily living (ADL) is one of the most important aspects in planning treatment for people with Parkinson disease (PD). The Barthel Index (BI) and modified Rankin Scale (mRS) are commonly used in neurological diseases. Objective: This study was conducted to confirm the validity and reliability of the BI and mRS in PD during ON and OFF medication phases. Methods: We included 260 individuals with a diagnosis of idiopathic PD. The disability in ADL was measured by the BI, mRS, Parkinson's Disease Questionnaire-39 (PDQ-39), Unified Parkinson Disease Rating Scale-Activities of Daily Living (UPDRS-ADL), and Schwab and England ADL scale (SE). Test–retest, inter-rater reliability, and internal consistency were assessed by the intra-class correlation (ICC) and Cronbach α coefficients. Dimensionality was evaluated by factor analysis. Convergent validity was assessed by the SE, Berg Balance Scale (BBS), PDQ-39 and UPDRS-ADL. Results: For the 260 participants (187 [71.9%] males; mean [SD] age 60.3 [12.3] years), both the BI and mRS achieved an acceptable level of test–retest and inter-rater reliability (ICC = 0.77 to 0.91) in ON and OFF medication phases. The Cronbach α for BI was 0.85 and 0.88, respectively. We found 1 and 2 factors for BI in ON and OFF phases, respectively. Investigation of convergent validity showed moderate to high correlation for the BI with the UPDRS-ADL, SE, PDQ-39 (ADL), BBS and mRS scores in ON and OFF phases (ρ=0.51-0.74) and mRS with SE, UPDRS-ADL, PDQ-39 (ADL) and BBS scores (ρ=0.48-0.82). Conclusion: The BI and mRS showed acceptable validity and reliability to measure the degree of disability in patients with PD in daily activities in both ON and OFF medication phases.