Supplementary information files for "Supporting sustainable return to work in large organizations: a cluster randomised feasibility trial of a multi-level intervention"

The IGLOo intervention combined e-learning for leaders/HR with structured toolkits for workers and managers to support RTW before and after return. Feasibility outcomes included recruitment, retention, engagement, acceptability, and usability. Secondary outcomes included RTW timing, sustained participation, mental health, and workplace factors.

A mixed methods process evaluation explored implementation and context. Retention, acceptability, and usability met targets, but recruitment and engagement were lower than expected. Potential mechanisms included improved confidence, communication, and self-management.

Organizational systems and pressures affected delivery. Exploratory analyses suggested different patterns of return-to-work trajectories across trial arms. Overall, the intervention was acceptable to participants who engaged with it, but recruitment barriers and organizational constraints require substantial modification before any future efficacy trial.<br><br>© The Author(s), CC BY 4.0</p>