Japanese Validation of a Daily Activities Scale Shows Strong Reliability in Mental Illness

For people living with mental illness, the rhythm of everyday life can be as important to recovery as any medication. Yet measuring whether someone has the right mix of work, leisure, household tasks, and self-care—the concept occupational scientists call occupational balance—has long been difficult in Japan, where existing assessment tools capture only a person’s general perception of balance without asking about the specific activities that shape it. A new study published in the Scandinavian Journal of Occupational Therapy offers a solution: a rigorously tested Japanese version of the Satisfaction with Daily Occupations and Occupational Balance instrument, known as the SDO-OB-J, that demonstrates solid reliability and validity among people with mental illness.

The research, led by Tomoe Ebisu of Kobe University Graduate School of Health Sciences together with colleagues at Osaka Kawasaki Rehabilitation University and Lund University in Sweden, was published on 2 July 2025 as an open-access article. Its central question was deceptively simple: does the Japanese adaptation of this Swedish interview-based tool produce stable, meaningful measurements when used with Japanese people living with mental illness? To answer it, the team followed the Consensus-Based Standards for the Selection of Health Measurement Instruments, or COSMIN, a widely respected framework for evaluating how well health measurement instruments perform.

The SDO-OB itself is an interview conducted by occupational therapists and organized into three sections covering four domains of daily life: work and studies, leisure, household and maintenance, and self-care. The first section measures activity level by asking whether the respondent engages in thirteen specific activities, with the number of affirmative answers summed into a score. The second section asks the respondent to rate satisfaction with those same thirteen activities on a seven-point scale ranging from worst to best, regardless of whether the activities were actually performed in the previous two months. The third section probes perceived occupational balance with one question per domain plus a general question—’Overall, how much do you feel you are doing various daily activities?’—rated on a five-point scale from far too little to far too much.

That final section is what distinguishes the SDO-OB from its predecessor, the SDO, which included only the activity level and satisfaction components. The balance questions generate a profile classifying respondents as under-occupied, in-balance, or over-occupied in each domain, reflecting the time-allocation perspective of occupational balance. Earlier versions of the instrument had already proven psychometrically sound in Sweden among people with mental illness, and Spanish versions had been validated for people with mental disorders and stroke survivors. But no Japanese version existed, leaving Japanese clinicians without an efficient tool that links perceived balance to concrete daily activities.

To fill that gap, the researchers recruited fifty-three participants from four healthcare facilities in a Japanese prefecture that provide vocational training, community activity support centre services, and assisted group homes. Eligible participants were between eighteen and sixty-five years old, not hospitalized at the time of data collection, had a psychiatric diagnosis under Chapter 5 of the tenth revision of the International Statistical Classification of Diseases, could recall their daily lives over the previous two months, and were native Japanese speakers. Roughly sixty percent were men, about half lived with family, and around half carried schizophrenia-related diagnoses. The sample size of fifty or more was chosen because COSMIN guidance considers it adequate for test-retest reliability studies and hypothesis testing for construct validity.

Each participant was interviewed twice, two weeks apart, between July 2023 and January 2024, with the same interviewer conducting both sessions. At the first time point, participants also completed the Trail Making Test Part B, a measure of neurocognition requiring them to alternately connect numbers and Japanese characters in sequence, and the Japanese version of the MOS 8-Item Short-Form Health Survey, which yields physical and mental component summary scores for health-related quality of life. Global functioning was rated with the Japanese version of the modified Global Assessment of Functioning scale, determined jointly by the interviewer and facility staff. Crucially, neither functioning scores nor cognitive test times changed significantly between the two interviews, confirming that participants’ conditions were stable enough for reliability to be meaningfully assessed.

The reliability results were striking. Weighted kappa coefficients, which measure agreement between repeated ratings while correcting for chance, reached 0.75 for total activity level—a value classified as substantial—0.85 for total activity satisfaction, classified as almost perfect, and 0.54 for general occupational balance, classified as moderate. This was the first study to examine the test-retest reliability of the complete SDO-OB instrument in people with mental illness, and the findings align with earlier Swedish studies of the SDO and a Spanish study of the SDO-OB in stroke survivors. Notably, the general balance question performed better here than in the Spanish stroke study, though the authors suggest that perceptions of general balance may be influenced by more confounding factors than the more concrete activity scores.

Construct validity was tested through seven pre-formulated hypotheses derived from previous research. The activity level and satisfaction scores showed no significant correlation with global functioning, neurocognition, or mental-related quality of life, supporting the predicted discriminant validity—the idea that a measure of daily activity engagement should not simply mirror measures of cognition or clinical functioning. Physical-related quality of life, however, correlated significantly with activity satisfaction, supporting convergent validity and echoing earlier findings. One hypothesis was only partly supported: activity satisfaction did not correlate with mental-related quality of life, contrary to expectations, which the authors attribute to the fact that quality of life is not a uniform concept.

The general balance question revealed its own pattern. Participants were classified as under-occupied, in-balance, or over-occupied, with twenty-one, twenty-three, and nine individuals in those groups respectively. The in-balance group scored significantly higher on mental-related quality of life than the under-occupied group, with mean T-values of 46.9 versus 42.0, a statistically significant difference. No differences emerged in global functioning, cognitive performance, or physical quality of life across the groups. The authors suggest that Japan’s mental health system—marked by many psychiatric care beds, long-term inpatients, and community support that relies heavily on families—may shape how occupational balance relates to functioning, and that daily-activity concepts like balance are likely more tied to real-world functioning than to neurocognition, whose link to outcomes is known to be indirect.

The study’s limitations are acknowledged: participants were all users of healthcare facilities, the sample was modest given the diversity of psychiatric diagnoses, and comparisons with Swedish cohorts were constrained by differing healthcare systems and sociodemographic profiles. Still, the verdict is clear. The SDO-OB-J showed relatively good test-retest reliability and construct validity, and the authors conclude it can serve as a first step in clinical practice for evaluating occupational balance among people with mental illness in Japan. Future work will test additional psychometric properties nationwide with larger, more diverse samples, and the Japanese manual and interview form are available on request from the first author. For a country working to shift psychiatric care from long hospital stays toward community life, a validated tool that captures not just how much people do, but how balanced and satisfying their daily occupations feel, could prove an quietly powerful instrument in the rehabilitation toolkit.

Subject of Research: Psychometric validation of a Japanese occupational balance assessment tool for people with mental illness

Article Title: Test–retest reliability and construct validity of a Japanese version of the Satisfaction with Daily Occupations and Occupational Balance for people with mental illness

Article References: Ebisu, T., Masuzawa, T., Yotsumoto, K., Hashimoto, T., Argentzell, E., & Eklund, M. (2025). Test–retest reliability and construct validity of a Japanese version of the Satisfaction with Daily Occupations and Occupational Balance for people with mental illness. Scandinavian Journal of Occupational Therapy, 32(1), Article 2526427. https://doi.org/10.1080/11038128.2025.2526427

Image Credits: AI Generated

DOI: 10.1080/11038128.2025.2526427

Keywords: occupational balance, mental illness, psychometrics, test-retest reliability, construct validity, occupational therapy, quality of life, Japan, assessment tool, daily activities, rehabilitation, kappa coefficient