Development of Two Barthel Index-Based Supplementary Scales for Patients with Stroke

Background: The Barthel Index (BI) assesses actual performance of activities of daily living (ADL). However, comprehensive assessment of ADL functions should include two other constructs: self-perceived difficulty and ability. Objective: The aims of this study were to develop two BI-based Supplementary Scales (BI-SS), namely, the Self-perceived Difficulty Scale and the Ability Scale, and to examine the construct validity of the BI-SS in patients with stroke. Method: The BI-SS was first developed by consultation with experts and then tested on patients to confirm the clarity and feasibility of administration. A total of 306 participants participated in the construct validity study. Construct validity was investigated using Mokken scale analysis and analyzing associations between scales. The agreement between each pair of the scales ’ scores was further examined. Results: The Self-perceived Difficulty Scale consisted of 10 items, and the Ability Scale included 8 items (excluding both bladder and bowel control items). Items in each individual scale were unidimensional (H$0.5). The scores of the Self-perceived Difficulty and Ability Scales were highly correlated with those of the BI (rho = 0.78 and 0.90, respectively). The scores of the two BI-SS scales and BI were significantly different from each other (p,.001). These results indicate that both BI-SS scales assessed unique constructs. Conclusions: The BI-SS had overall good construct validity in patients with stroke. The BI-SS can be used as supplementar