A consumer co-designed community physical activity program for Australians living with osteoarthritis (CASCADE-OA): A randomised controlled trial protocol.

Objective: This protocol will detail the methodology of the CASCADE-OA trial that will determine the effectiveness of an evidence-based and co-designed walking program, Walk with Ease Australia in increasing physical activity levels in people with osteoarthritis (OA). Design: We will undertake a two-arm parallel assessor blinded RCT in a hybrid type 1 effectiveness-implementation design. 414 participants with a clinical diagnosis of knee or hip OA will be recruited across Australia through state and territory arthritis consumer advocacy groups, an OA management program in a public hospital setting, and social media. Participants with co-existing inflammatory arthritis or those already meeting physical activity guidelines will be excluded. Participants will be randomised 1:1 into either the Walk with Ease Australia + Fitbit™ group (intervention) or the Fitbit™ only group (comparator). The intervention period will be 12 weeks and participants will be followed for 12 months from randomisation. The primary outcome is average daily step count at 12 weeks as assessed by Fitbit™. Secondary outcomes include pain, disability, quality of life, self-efficacy, work absenteeism and healthcare utilisation. Implementation outcomes will be collected based on the RE-AIM framework domains and process evaluation framework for complex interventions. Results: The trial was registered on the Australia and New Zealand Clinical Trials Registry (ACTRN12625000185460) on February 17th, 2025 and received ethics approval from the Northern Sydney Local Health District Human Research Ethics Committee (2024/ETH01898). Conclusion: CASCADE-OA will determine whether Walk with Ease Australia will support people in the community with OA in increasing physical activity and improving symptoms.