To verify the effect of adjusting the challenge–skill balance with respect to rehabilitation process. A single-blind, two-arm, parallel-group, randomized controlled trial. Recovery rehabilitation unit of Harue Hospital, Japan. The trial included 72 clients (mean (SD): age, 74.64 (9.51) years; Functional Independence Measure score, 98.26 (15.27)) with cerebral or spinal disease or musculoskeletal disease. Clients were randomly divided into two groups: the experimental group, who received occupational therapy with adjustment of the challenge–skill balance, and the control group who received conventional occupational therapy. Time from admission to discharge was considered the implementation period; the final evaluation was conducted at three months after discharge. The primary outcome was subjective quality of life (Ikigai-9). Secondary outcomes were the health-related quality of life (EuroQol–5 Dimensions, Five Levels (EQ-5D-5L)), the Flow State Scale for Occupational Tasks, and the Functional Independence Measure. A cost-effectiveness analysis was conducted using total cost and quality-adjusted life-year based on the EQ-5D-5L. Significant differences were observed between the experimental and control groups with respect to the Ikigai-9 score (P = 0.008) and EQ-5D-5L (P = 0.038), and the effect sizes were 0.76 (95% confidence interval [CI]: 0.27–1.24) and 0.62 (95% CI: 0.14–1.10), respectively. No significant between-group differences in other outcomes were observed, for example, the Functional Independence Measure score improved in both experimental and control groups (119.80 (5.50) and 118.84 (6.97), respectively. The incremental cost-effectiveness ratio was US$5518.38. Adjusting the challenge–skill balance may be a useful approach to improve the participant’s subjective quality of life in the rehabilitation process.

OBJECTIVE. We sought to investigate whether occupational therapy that includes adjusting the challenge–skill balance improves health-related quality of life (HRQOL) for older adults in comparison with standard occupational therapy. METHOD. In this single-blind, randomized controlled trial, 56 older adults were assigned to two groups that received 10 sessions of occupational therapy with and without adjustment of challenge–skill balance. The primary outcome was change in HRQOL after 10 sessions of occupational therapy. RESULTS. Significant differences were observed in HRQOL using the EuroQol–5 Dimension score (p = .022, d = 0.76) and the eight-item Short-Form Health Survey scores for general health (p = .001, d = 0.99) and in flow experience using the Flow State Scale for Occupational Tasks (p = .008, d = 0.82). CONCLUSION. Assessment and adjustment of the challenge–skill balance of activities may effectively improve older adults’ HRQOL.