Concerns on methodological assumptions in the health economic Evaluation of return-to-work interventions.

This Key Paper Evaluation examines a recent modeling study of return-to-work (RTW) interventions comparing inpatient multimodal occupational rehabilitation (I-MORE) with outpatient Acceptance and Commitment Therapy (ACT). The authors link a randomized trial to seven years of registry follow-up and project costs and effects over a 25-year horizon from healthcare and societal perspectives. We commend the clear intervention definitions, transparent multistate-to-Markov approach, and probabilistic analyses. However, the study's headline finding - lifetime dominance of I-MORE when productivity is counted - hinges on structural assumptions: transition intensities are frozen beyond four years, and within-state absence-day differences are held constant thereafter, generating persistent productivity gains even after state prevalences converge. Health-related quality of life is observed only to 14 months and then modeled as state-specific constants, compressing incremental quality-adjusted life years and leaving the healthcare-only incremental cost-effectiveness ratio unfavorable. We argue that lifetime savings should be treated as upper-bound estimates and that decision relevance would be strengthened by waning-effect scenarios, mid-term horizons, and tests of the absorbing disability state. We also highlight the need for diagnosis-by-treatment analyses and stepped-care sequences given the heterogeneous population and fixed-dose ACT comparator. Overall, the paper advances RTW modeling while underscoring how perspective and structure shape long-run conclusions.