Reliability and validity assessment of an apathy scale for home-care patients with Parkinson’s disease: a structural equation modeling analysis

[Purpose] Based on the Starkstein Apathy Scale, an apathy scale was developed for home-care patients with Parkinson's disease using structural equation modeling (SEM), with which the data compatibility of extraction factors can be verified. [Subjects and Methods] The participants were 122 home-care patients with Parkinson's disease (mean age: 70.9 ± 7.8 years) who were member of the Aomori branch or Tohoku/Hokkaido block of the Japan Parkinson's Disease Association. A questionnaire survey (anonymous, self-administered) was carried out by distributing and collecting questionnaires by mail or a collective survey at a workshop. Construct validity was evaluated by confirmatory factor analysis using SEM. Internal consistency was investigated using Cronbach's alpha coefficient. Criterion-related validity was assessed by correlation analysis with the total score of the Beck Depression Inventory. [Results] Concerning construct validity, 11 of the 14 question items of the original scale were extracted. Cronbach's α of this scale was 0.939. For criterion-related validity, Spearman's rank correlation coefficient was 0.831. [Conclusion] The construct validity, internal consistency, and criterion-related validity of the 11-item apathy scale were confirmed. The 11-item apathy scale can serve as a useful tool for the efficient and effective assessment of rehabilitation, establishment of rehabilitation goals and programs for patients with Parkinson's disease.