Chronic pain affects around 28 million adults in the UK and is associated with impaired work ability, reduced productivity and increased sickness absence. Access to work-focused support within healthcare services is limited, and most employers do not routinely provide structured assistance for employees living with chronic pain. The Pain-at-Work Toolkit is a co-created, web-based intervention designed to improve work ability, self-management, and workplace experiences for employees living with chronic pain. A feasibility trial demonstrated strong acceptability, exceptional recruitment and potential improvements in work ability, providing clear justification for progression to a fully powered evaluation. This paper describes the protocol for a definitive cluster randomised controlled trial to evaluate the effectiveness, cost-effectiveness and implementation of the Pain-at-Work Toolkit.

This two-arm, open-label cluster-randomised controlled trial will recruit at least 70 organisations (minimum 35 clusters per arm) and at least 685 participants. Organisations will be randomised 1:1 to (a) support-as-usual (SAU) or (b) SAU plus the Pain-at-Work Toolkit, and Pain-at-Work Manager’s Toolkit as an implementation-support component. The primary outcome is work ability at 3 months, measured using the Work Ability Index (three-item version). Secondary outcomes include work self-efficacy, sickness absence, presenteeism, productivity loss, job satisfaction, job stressfulness, turnover intentions, anxiety, depression and health-related quality of life. A mixed-methods process and implementation evaluation will assess fidelity, contextual influences and mechanisms of impact. A health economic evaluation will estimate cost-effectiveness from employer and societal perspectives. Analyses will follow intention-to-treat principles using multilevel modelling.

Ethical approval was granted by the University of Nottingham Faculty of Medicine and Health Sciences Research Ethics Committee (Ref: FMHS 1200226) and the UK Health Research Authority and Health and Care Wales (IRAS 367449). Findings will be disseminated through peer-reviewed publications, conference presentations, stakeholder reports and public summaries.

NCT07600892.