Highlights
- The CHAIN intervention (cycling and education) resulted in a statistically significant improvement in Hip Disability and Osteoarthritis Outcome Score (HOOS) ADL subscale compared to usual physiotherapy care (p=0.0023).
- The adjusted mean difference between groups was 6.9 points, narrowly missing the predefined minimum clinically important difference (MCID) of 7.4.
- Economic analysis revealed an incremental cost-effectiveness ratio (ICER) of £4,092 per QALY, well within the UK NICE threshold for value.
- Community-based group exercise programs offer a feasible and safe alternative to traditional hospital-centered physiotherapy for hip osteoarthritis management.
Background: The Burden of Hip Osteoarthritis
Osteoarthritis (OA) of the hip remains a primary driver of chronic disability and healthcare expenditure globally. In the United Kingdom, hip OA significantly impacts the quality of life for millions, often leading to reduced mobility, chronic pain, and eventually, the need for total hip arthroplasty. Current clinical guidelines, including those from the National Institute for Health and Care Excellence (NICE), emphasize the importance of therapeutic exercise and education as first-line treatments. However, the delivery of these interventions varies widely, often alternating between individual hospital-based physiotherapy and self-managed home exercise programs.
The Cycling and Hip Pain (CHAIN) intervention was developed to address these delivery challenges by utilizing community leisure facilities and a group-based format. By combining targeted education with progressive static cycling, the program aims to improve joint function and patient self-efficacy. The Clinical and Cost-Effectiveness of a Cycling and Education Intervention versus Usual Physiotherapy Care (CLEAT) trial was designed to rigorously evaluate whether this community-based model could outperform standard physiotherapy practices within the National Health Service (NHS) framework.
The CLEAT Trial: Study Design and Methodology
CLEAT was a pragmatic, single-center, randomized controlled trial conducted in Bournemouth, UK. The trial recruited 221 participants aged 18 and older who met the primary-care criteria for exercise referral due to activity-related hip pain and stiffness. For younger participants (18–45 years), radiographic confirmation of OA was required to ensure diagnostic accuracy. Participants were randomized 1:1 to either the CHAIN intervention or usual physiotherapy care.
The Interventions
The CHAIN group participated in an 8-week program held at a local leisure center. Each session included 30 minutes of education focusing on OA management, followed by 30 minutes of supervised static cycling. The cycling component was progressive, tailored to individual tolerances. In contrast, the usual care group received standard physiotherapy, which typically involved one-to-one sessions at a local hospital or via telephone, reflecting the pragmatic nature of the trial and the standard of care at the time.
Primary and Secondary Endpoints
The primary outcome measure was the difference in the Hip Disability and Osteoarthritis Outcome Score (HOOS) activities of daily living (ADL) subscale at 10 weeks post-treatment. Secondary outcomes included pain scores, quality of life (EQ-5D-5L), and a comprehensive economic evaluation from the perspective of the NHS and personal social services.
Clinical Outcomes: Does Cycling Outperform Usual Care?
The trial findings, published in The Lancet Rheumatology, indicate a clear statistical advantage for the CHAIN intervention. Between February 2020 and April 2023, 110 participants were assigned to the CHAIN group and 111 to usual care. The mean age was 64.4 years, with a demographic profile reflecting the local population (98% White).
Functional Improvements
Participants in the CHAIN group saw their mean HOOS ADL scores rise from 60.8 at baseline to 73.5 at the 10-week mark. Those in the usual care group improved from 59.3 to 65.4. After adjusting for baseline variables, the mean difference between the groups was 6.9 points (95% CI 2.5–11.2; p=0.0023). While this confirms a statistically significant benefit for the cycling intervention, it is noteworthy that the difference fell slightly short of the pre-defined MCID of 7.4 points.
Safety and Adverse Events
Safety data were encouraging. No treatment-related serious adverse events were reported in either group, suggesting that progressive static cycling is a safe modality even for patients with significant joint symptoms and varying levels of baseline fitness.
Economic Evaluation: A Cost-Effective Community Solution
One of the most compelling aspects of the CLEAT trial is its economic analysis. In an era of constrained healthcare budgets, the scalability of interventions is as critical as their clinical efficacy. The CHAIN intervention was found to be highly cost-effective, costing approximately £4,092 per quality-adjusted life year (QALY) gained. This figure is substantially lower than the £20,000 to £30,000 threshold typically utilized by NICE to determine the value of medical interventions in the UK. This suggests that transitioning hip OA management from hospital-based individual physiotherapy to community-based group cycling programs could provide significant value for money while freeing up specialized hospital resources.
Critical Interpretation and Clinical Implications
The CLEAT trial provides high-quality evidence supporting the shift toward community-based, group-led rehabilitation models. The success of the CHAIN intervention can likely be attributed to several factors beyond the mechanical benefits of cycling. The group format fosters social support and peer learning, while the educational component empowers patients with the knowledge to manage their condition long-term.
The MCID Nuance
Clinicians must weigh the statistical significance against the fact that the 6.9-point difference did not meet the 7.4-point MCID. However, MCID thresholds are often debated and can vary across different patient populations. The lower bound of the confidence interval (2.5) and the upper bound (11.2) suggest that while some patients may experience modest gains, others may see improvements that far exceed the clinical importance threshold. Given the low cost and safety profile, the ‘near-miss’ of the MCID may not be a deterrent for implementation.
Limitations and Generalizability
The study’s primary limitations include its single-center design and the lack of ethnic diversity among participants, which may limit the generalizability of the findings to more diverse urban populations. Furthermore, the 10-week follow-up provides insight into short-term gains, but the durability of these benefits over 12 to 24 months remains to be seen. Further research should focus on long-term adherence to cycling and the potential for these programs to delay the need for surgical intervention.
Conclusion
The CLEAT trial demonstrates that a community-based cycling and education program is superior to usual physiotherapy care for improving functional outcomes in patients with hip osteoarthritis. With a favorable safety profile and exceptional cost-effectiveness, the CHAIN model offers a scalable solution for health systems grappling with the rising burden of musculoskeletal disease. As healthcare moves toward more personalized yet community-integrated care, programs like CHAIN provide a blueprint for effective, patient-centered chronic disease management.
Funding and Clinical Trial Information
This study was funded by the National Institute for Health and Care Research (NIHR) for Patient Benefit Programme. The trial is registered with ISRCTN, number ISRCTN19778222.
References
Wainwright TW, Immins T, Docherty S, et al. Clinical and cost-effectiveness of a cycling and education intervention versus usual physiotherapy care for the treatment of hip osteoarthritis in the UK (CLEAT): a pragmatic, randomised, controlled trial. Lancet Rheumatol. 2025;7(11):e764-e775. doi:10.1016/S2665-9913(25)00102-X