Psychometric properties of the Assessment of Positive Occupation 15 for individuals with physical illness.

Objectives: The Assessment of Positive Occupation 15 (APO-15) is a scale initially developed to evaluate participation in well-being-promoting occupations among individuals with mental illness. This study examines the psychometric properties of the Japanese version of the APO-15 for individuals with physical illness, focusing on its validity, reliability, and interpretability.

Methods: We evaluated the psychometric properties of the APO-15 using a sample of 1,259 individuals with physical illness living at home, in hospitals, and in nursing homes. Validity was evaluated using confirmatory factor analysis (CFA) to confirm the factor structure, and concurrent validity was examined by correlating APO-15 scores with measures of happiness and psychological distress. Reliability was assessed by internal consistency analysis using Cronbach's alpha, and item difficulty was analyzed using the Rasch Rating Scale Model (RSM). Interpretability was established through a T-scale-based five-level criterion for client status.

Results: The APO-15 showed strong psychometric properties. CFA indicated a good fit for the factor structure (RMSEA= 0.100, CFI= 0.944, TLI= 0.930). Internal consistency was high, with a Cronbach's alpha of 0.914. Item difficulty analysis revealed a bias towards easier items, consistent with previous findings in mental illness populations. The T-scale-based five-level criterion effectively classified client status, though significance was noted between most levels except levels 1 and 2.

Conclusion: The Japanese version of the APO-15 is a reliable and valid tool for assessing occupational participation and promoting well-being among individuals with physical illness. It provides a robust framework for occupational therapists to support clients' well-being through targeted occupational engagement.