A joint ASAS/SPARTAN initiative proposes revised diagnostic criteria for axial spondyloarthritis

The 2009 ASAS criteria for the diagnosis of axial spondyloarthritis are based on radiographic imaging/MRI, as well as genetic and clinical features of the disease, and have a sensitivity and specificity of 82.9% and 84.4%, respectively [1]. Prof. Walter P. Maksymowych (University of Alberta, AB, Canada) presented the results of CLASSIC, a combined initiative of ASAS and SPARTAN aimed at validating the performance of the 2009 ASAS criteria [2].

Participants were included in the Classification in Axial Spondyloarthritis Inception Cohort Study (CLASSIC) if they were referred to a rheumatologist with undiagnosed chronic back pain occurring before 45 years of age, with ≥3 months' duration, and with suspicion of axial spondyloarthritis [2]. Global assessments were conducted to validate the criteria using clinical assessment, laboratory analyses, pelvic radiographs, local MRI, and a centralised review of imaging data. A prespecified sensitivity of ≥75% and specificity of ≥90% was used to select diagnostic criteria. A total of 1,015 participants from 61 centres in 27 countries were included.

Following central review of data, 36.4% of participants in the cohort were diagnosed with axial spondyloarthritis. Several diagnostic models were proposed based on imaging, genetic, and clinical criteria. The model reaching the highest specificity (sensitivity of 79.5% and specificity of 90.4% for local readers) was based on a score ≥11, calculated as the sum of the following:

• MRI indicating axial spondyloarthritis (8) or radiographic sacroiliitis (7)
• HLA-B27 positivity (4)
• Inflammatory back pain (3)
• Peripheral arthritis (1)
• Inflammatory bowel disease (1)
• Acute anterior uveitis (1)
• Heel enthesitis (1)
• Elevated C-reactive protein (1)
• Psoriasis (1)

The adoption of these revised criteria was voted on by joint ASAS-SPARTAN members and was accepted by 158 votes in favour, 151 against, and 9 abstentions.

1. Maksymowych WP, et al. Ann Rheum Dis. 2009;68(6):777-83.
2. Maksymowych WP, et al. The assessments in Spondyloarthritis International Society (ASAS) and Spondyloarthritis Research and Treatment Network (SPARTAN) revised classification criteria for axial spondyloarthritis: Development and validation in the Classification in Axial SpA Inception Cohort Study. ACR Convergence, 24–29 October 2025, Chicago, IL, USA.

Medical writing support was provided by Mihai Surducan, PhD.

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Posted on 29 October 2025