New International axSpA Classification Criteria: Why They Matter to Patient Organisations
Researchers from the Assessment of SpondyloArthritis International Society (ASAS) and the Spondyloarthritis Research and Treatment Network (SPARTAN) have developed revised classification criteria for axial spondyloarthritis (axSpA). First presented at ACR Convergence 2025 and highlighted again at EULAR 2026, the new criteria represent an important development for the global axSpA community.
These revised classification criteria are designed for research, rather than for diagnosing patients in the clinic. They help researchers identify people with axSpA for clinical studies and trials.
The original ASAS classification criteria were published in 2009 and have been widely used internationally for more than 15 years. However, during that time, concerns were raised that some people without axSpA could potentially meet the criteria and be included in research studies. Because chronic back pain is common in the general population and can lead to a mis – or ‘over’ – diagnosis, ASAS and SPARTAN undertook a comprehensive review to improve the accuracy of patient selection for research.
The revised criteria were developed using data from the international CLASSIC study, which involved more than 1,000 people with undiagnosed chronic back pain suggestive of axSpA. Compared with the previous criteria, they place greater emphasis on imaging findings, particularly MRI evidence of inflammation and structural changes in the sacroiliac joints, alongside key clinical and biological features associated with the disease. The result is improved specificity while maintaining good sensitivity, helping researchers identify more clearly defined study populations.
At first glance, classification criteria may seem like a technical topic with limited relevance to patients. However, they play an important role in shaping the research evidence that ultimately influences future diagnosis, treatment and care.
So why should patient organisations care?
Because the criteria used in research influence the evidence base that shapes future care. More accurate classification criteria can help ensure that clinical trials include people who genuinely have axSpA, leading to more reliable findings about treatment effectiveness, disease progression and unmet patient needs. Better research today can contribute to better care tomorrow, and avoid people being wrongly diagnosed.
Most importantly, patient organisations have a vital role in ensuring that future research focuses on outcomes that matter to people living with axSpA, including pain, fatigue, quality of life, mental wellbeing, work participation and access to effective treatments.
The revised criteria are a reminder that our understanding of axSpA continues to evolve. Through collaboration between researchers, clinicians and patient organisations, the goal remains the same: generating better evidence and improving the lives of people living with axSpA worldwide.
References
1. Maksymowych WP, van der Heijde D, Caplan L, et al. The Assessment of Spondyloarthritis International Society (ASAS) and Spondyloarthritis Research and Treatment Network (SPARTAN) Revised Classification Criteria for Axial Spondyloarthritis: Development and Validation in the Classification of Axial SpA Inception Cohort Study (CLASSIC). Presented at ACR Convergence 2025.
2. EULAR 2026 Congress. Updated ASAS-SPARTAN Classification Criteria for Axial Spondyloarthritis and Updated Recommendations on Imaging in Spondyloarthritis. Presented at EULAR Congress 2026, London.
3. Maksymowych WP. Redefining the Diagnosis of Axial Spondyloarthritis: The ASAS-SPARTAN 2025 Classification Criteria. Conference interview and discussion of the rationale, methodology and implications of the revised criteria. touchIMMUNOLOGY, 2025.
4. Assessment of SpondyloArthritis International Society (ASAS). ASAS Classification Criteria for Axial Spondyloarthritis (2009). Original classification criteria on which the revised criteria were based. (Referenced in discussions of the 2025 revision.)
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