Citation, DOI and article data
Axial spondyloarthrititis (SpA) is a clinical subset of the seronegative spondyloarthritides that present primarily with back pain and morning stiffness. There is a long delay, on average 14 years, between symptoms onset and diagnosis 1.
The prevalence of axial SpA is ~1% 1. Age of onset is in the 3rd and 4th decades 2.
Assessment of SpondyloArthritis International Society (ASAS) criteria for the diagnosis of axial spondyloarthropathy 1:
- ≥3 months of back pain and age of onset ≤45 years
- sacroiliitis on imaging and ≥1 clinical feature or HLA-B27 and ≥2 clinical features
- clinical features
- inflammatory back pain: insidious onset; improvement with exercise but not with rest; night pain; morning back stiffness ≥30 minutes; alternating gluteal pain 2
- heel enthesitis
- Crohn disease
- good response to NSAIDs (absent pain) 24-48 hours after a full dose 2
- family history of SpA
- elevated CRP
Imaging forms an important part of the work-up as the clinical features are somewhat non-specific 2. Radiographic evidence of SpA will be present in ~50% of patients at initial diagnosis. Some will progress to having radiographic evidence whilst others will never have radiographic evidence of SpA 1.
Sacroiliac joint x-rays are the first-line modality. Definite radiographic sacroiliitis is characterized by the New York Criteria as bilateral grade 2 or unilateral grade 3 2.
Sacroiliac joint MRI is the second line modality. See ASAS sacroiliitis classification system for details.
- 1. Tsoi C, Griffith J, Lee R, Wong P, Tam L. Imaging of Sacroiliitis: Current Status, Limitations and Pitfalls. Quant Imaging Med Surg. 2019;9(2):318-335. doi:10.21037/qims.2018.11.10
- 2. Poddubnyy D. Classification Vs Diagnostic Criteria: The Challenge of Diagnosing Axial Spondyloarthritis. Rheumatology (Oxford). 2020;59(Suppl4):iv6-iv17. doi:10.1093/rheumatology/keaa250