Co-developing a vocational rehabilitation intervention for individuals with chronic low back pain across a regional spine centre and three municipalities in Denmark: a three-stage intervention development study guided by the Medical Research Council

OBJECTIVES: To co-develop the Stay-At-Work (SAW) intervention, a person-centred, interdisciplinary, cross-sectoral vocational rehabilitation (VR) programme for individuals on, or at risk of, sick leave due to chronic low back pain (CLBP) and to advance methodological understanding of how evidence, qualitative insights, stakeholder input and programme theory can be systematically integrated and operationalised into concrete intervention components. DESIGN: A three-stage intervention development study, guided by the Medical Research Council framework for complex interventions, involving evidence review and stakeholder consultation (previously reported); multistakeholder co-design; and prototyping in clinical settings. SETTING: The intervention was developed within a Danish public healthcare and welfare context, involving a secondary care spinal service, municipal employment services (n=3), municipal rehabilitation services (n=3) and general practice. PARTICIPANTS: Stage 1: 17 individuals on long-term sick leave due to CLBP participated in interviews and focus groups. Stages 2 and 3: The co-design group included individuals living with CLBP (n=2); clinicians from a secondary care spine service (n=2) and municipal rehabilitation services (n=6); general practitioners (n=2); municipal employment service professionals (n=3) and local managers (n=3); and employer and employee representatives (n=2). Participants were purposively recruited based on their roles and experience in VR and return-to-work processes and contributed across different stages of intervention development. RESULTS: The SAW intervention consists of eight structured activities, developed through multistakeholder co-design and underpinned by a programme theory with four core mechanisms: (1) strengthened interprofessional and cross-sectoral understanding and collaboration; (2) stronger alignment around functional capacity and work ability; (3) addressing psychological vulnerability through systematic screening and support; and (4) enhanced coordination of care and rehabilitation efforts across services.Stakeholder input from the co-design group informed the intervention's content and procedures, thereby improving alignment with local contexts and strengthening cross-sector collaboration. Some proposals were excluded due to inconsistency with clinical guidelines. CONCLUSION: : The Region of Southern Denmark's Research Registry (journal no. 23/44927).