Intervention fidelity and engagement: from practical assessment in a shoulder pain trial to the development of an international reporting guideline

This thesis examines intervention fidelity—how well an intervention is delivered and engaged with as intended. Fidelity is often overlooked in education and exercise trials for shoulder pain, creating uncertainty about effectiveness. Initially, the thesis investigates fidelity in a clinical trial on education and exercise for shoulder pain, focusing on provider delivery, participant engagement, and the provider-participant relationship. Challenges in assessing and reporting fidelity led to the development of ReFiND, a new international guideline for reporting fidelity in non-drug, non-surgical trials. ReFiND enhances transparency and reproducibility, helping researchers and clinicians better understand and apply health interventions.