Evaluation of psychometric properties of the activities of daily living scale of motor function used by caregivers using Rasch analysis

[Purpose] We developed a prototype version of the Self-Assessment Burden Scale-Motor as a screening questionnaire for the need of care based on the evaluation of patients’ activities of daily living. The questionnaire is comprised of seven items, each of which is scored on a 7-point Likert scale. This study aimed to examine the psychometric properties of the questionnaire using Rasch analysis. [Participants and Methods] A total of 200 individuals completed the questionnaire. Rasch analysis to investigate the rating scale structure and examine the structural validity and reliability of the scale. The unidimensionality of the items was examined using the mean square infit values and principal component analysis of residuals. The separation reliability of the scale was also examined. [Results] The rating scale structure can be improved by collapsing several categories (from seven categories to four categories). Unidimensionality was found for seven items. The separation reliability was acceptable for item calibrations and persons. [Conclusion] Inclusion of seven items with a 4-category rating scale was appropriate for the Self-Assessment Burden Scale-Motor questionnaire. Future studies should examine the intra-rater reliability and the criterion-related validity in more depth and develop a new scale to evaluate cognitive function.