Cost-Effectiveness of Individualized Occupational Therapy for Inpatients With Schizophrenia: Two-Year Follow-Up of a Multicenter Randomized Controlled Trial

IMPORTANCE: Schizophrenia typically requires long-term treatment, making cost-effective interventions essential, yet the cost-effectiveness of individualized occupational therapy (IOT) remains unclear. OBJECTIVE: To compare the cost-effectiveness of IOT plus group occupational therapy (GOT) with GOT alone for inpatients with schizophrenia over 2 yr. DESIGN: Secondary analysis of data from a multicenter, two-arm, parallel randomized controlled trial. SETTING: Fourteen clinical facilities. PARTICIPANTS: Sixty-two inpatients with schizophrenia who completed 2-yr follow-up. INTERVENTION: GOT alone or IOT+GOT during 3 mo of hospitalization. OUTCOMES AND MEASURES: Quality-adjusted life-years (QALYs) and total medical costs from a health care payer perspective over 2 yr. RESULTS: Compared with GOT alone (n = 30), IOT+GOT (n = 32) produced greater cumulative QALYs (M difference = 0.156) and lower total medical costs (M difference = -¥290,784). The incremental cost-effectiveness ratio was -¥3,304,420 per QALY gained. Incremental net benefit was positive at willingness-to-pay thresholds of ¥5,000,000 and ¥6,000,000 per QALY. The cost-effectiveness acceptability curves showed a 94.2% probability of cost-effectiveness at a threshold of ¥6,000,000. Cost data were complete for approximately 40% of participants; missingness was addressed using multiple imputation, with complete-case sensitivity analysis yielding directionally consistent findings. CONCLUSIONS AND RELEVANCE: IOT+GOT was more cost-effective than GOT alone over 2 yr, supporting its wider adoption as an economically sound rehabilitation strategy for clients with schizophrenia. Given the extent of missing cost data, the results should be interpreted with appropriate caution. These findings offer long-term economic evidence to inform mental health policies and resource allocation in psychiatric care. Plain-Language Summary: Schizophrenia often requires long-term treatment, resulting in substantial health care costs. This study examined whether adding individualized occupational therapy to standard group occupational therapy offers a more cost-effective approach for inpatients with schizophrenia. Sixty-two patients were followed for 2 years after receiving either group occupational therapy alone or a combination of individualized occupational therapy and group occupational therapy during hospitalization. The results indicated that patients who received individualized occupational therapy and group occupational therapy experienced greater improvements in quality of life and slightly lower total medical costs. Furthermore, the cost-effectiveness analysis showed a 94.2% probability that the intervention would be cost-effective under Japan's commonly accepted willingness-to-pay threshold. These findings suggest that individualized occupational therapy combined with group occupational therapy is a potentially cost-effective strategy for schizophrenia rehabilitation. This evidence supports the integration of individualized occupational therapy into standard psychiatric rehabilitation programs and may inform future mental health policy and resource allocation.