Background/Purpose: Classification of non-radiographic axial spondyloarthritis (nr-axSpA) requires the presence of Assessment of Spondyloarthritis international Society (ASAS) criteria for AxSpA, without radiologic evidence of sacroiliitis according to the modified New York Criteria. Existing evidence is limited relating to diagnostics in a real-world setting. The aim of this analysis was to investigate how patients are being classified as nr-axSpA in a real-world consulting sample.

Methods: Data were taken from the 2014 nr-axSpA Disease Specific Programme a cross-sectional, multi-national survey of nr-axSpA patients and their rheumatologists conducted in France, Germany, Italy, Spain and the UK. Physicians were asked to recruit their next 2 consecutive, consulting nr-axSpA patients. Inclusion in the survey was based on diagnosis of nr-axSpA by the rheumatologist, regardless of how the patient was actually diagnosed. No specific classification criteria were required. Physicians completed patient record forms containing patient demographics, clinical measurements and symptomology at diagnosis and criteria used to classify the patient with nr-axSpA. Observations were weighted to ensure findings were more representative of the patient population. The weight was applied when calculating all percentages, means and SDs.

Results: A total of 631 patients were included in the analysis (mean age 41.8±12.0 [SD], 70.4% male). Physicians reported that in over half (52.5%) of their patients, the nr-axSpA diagnosis was made using the ASAS criteria, however, 29.5% were diagnosed without any form of classification criteria. The majority (93.7%) of patients had inflammatory back pain (IBP) at diagnosis, while 21.7% had enthesitis, 3.4% had uveitis, 9.4% had dactylitis and 2.9% had psoriatic skin lesions. A family history of Ankylosing Spondylitis (AS) was reported in 18.5% of patients. Mean time since diagnosis was 51.6±59.9 months, while 17.4% of patients were 45 or older at onset of disease. Evidence of sacroiliitis was identified at diagnosis via X-ray or magnetic resonance imaging in 69.1% of patients. Only 149 patients had further information reported regarding sacroiliitis at diagnosis; 56.7% had IBP at diagnosis and sacroiliitis either grade ≥2 bilaterally or grade ≥3 unilaterally, fulfilling the classification for an AS diagnosis. 

Conclusion: While there are guidelines in place to aid the classification of nr-axSpA, in real-world practice it appears that there remains some inconsistency in how physicians classify the condition. Under-use of the recommended guidelines suggests an unmet need in accurate classification of nr-axSpA and therefore optimal treatment decisions for patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/standards-for-the-classification-of-non-radiographic-axial-spondyloarthritis-a-european-real-world-study/