Protocol for a pilot cluster randomised controlled trial of a multicomponent sustainable return to work IGLOo intervention.

Abstract Background Long-term sickness costs UK businesses approximately £7 billion per annum. Most long-term sickness absences are attributed to common mental health conditions, which are also highly prevalent in people with acute or musculoskeletal health conditions. The IGLOo intervention aims to support employees return to and remain in work following long-term sickness absence. The intervention will be piloted in a randomised controlled trial (RCT) to examine the feasibility of the intervention (primary outcome), and to inform a fully powered definitive trial to evaluate sustainable return to work (RTW) in people with primary or secondary mental ill-health who go on long-term sick leave. Methods and Design: A two-arm feasibility randomised controlled trial (with a 30-month study period including 12 month follow up) of the IGLOo (Individual, Group, Leaders, Organisation, overarching context) intervention will be conducted in large organisations (≥ 600 employees) from the Yorkshire and Humberside regions, in the United Kingdom. Eight consenting organizations will be recruited and randomised to the intervention or control arms of the study (1:1 ratio), with a minimum recruitment target of 13 employees and 13 managers eligible to participate from each. Organisations assigned to the control group will continue with their usual practice. Feasibility data will include data collected on recruitment, retention and attrition of participants, completion of research outcome measures and intervention compliance. Measurements of mental health, RTW, work outcomes, quality-of-life, workplace support and communication and other demographic data will be taken at baseline, 3, 6, 9 and 12 months in all participants. Qualitative interviews and survey data will explore the experiences of participants, acceptability of the intervention components and evaluation measures. Exploratory economic evaluation will be conducted to further inform a definitive trial. Discussion The findings from this pilot study will help to inform the development of a definitive cluster RCT designed to examine the efficacy of this intervention on health and work-related outcomes in UK workers on long-term sick leave. Trial Registration ISRCTN11788559 (prospectively registered, date registered 6th October 2022)