Citation, DOI, disclosures and article data
Citation:
Grieve J, Yap J, Hacking C, et al. Undifferentiated spondyloarthritis. Reference article, Radiopaedia.org (Accessed on 13 Mar 2025) https://doi.org/10.53347/rID-43414
Undifferentiated spondyloarthritis (uSpA), also known as undifferentiated arthritis, is a non-specific mono- or polyarthropathy that lacks the clinical, serological and radiological features that would allow specific diagnosis. It often turns out to be an early presentation of a more well-known form of arthritis.
The prevalence of undifferentiated spondyloarthritis is estimated at ~1% 4.
Back pain, enthesitis, and peripheral arthritis are common, as well as extra-skeletal manifestations such as dactylitis and fatigue 1.
Depends on the underlying cause. Most cases reveal themselves to be either:
Markers
Only 50% of presentations have abnormal levels of acute-phase reactants (CRP, ESR), and only 10% are positive for rheumatoid factor despite many eventually declaring themselves as rheumatoid arthritis 3.
Treatment and prognosis
A specific diagnosis is usually reached within three months, commonly:
A small number will remain "undifferentiated", and ~45% will recover without a more specific diagnosis 1.
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1. Thabet MM, Huizinga TW, van der Heijde DM, van der Helm-van Mil AH. "The prognostic value of baseline erosions in undifferentiated arthritis. Arthritis Res Ther." 2009;11(5):R155. Epub 2009 Oct 15.
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2. Lukas C, Combe B, Ravaud P, Sibilia J, Landew R, van der Heijde D. "Favorable effect of very early disease-modifying antirheumatic drug treatment on radiographic progression in early inflammatory arthritis: Data from theÉtude et Suivi des polyarthrites indifférenciées récentes (study and followup of early undifferentiated polyarthritis)." Arthritis Rheum. 2011 Jul;63(7):1804-11.
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3. Krabben A, Huizinga TW, van der Helm-van Mil AH. Undifferentiated arthritis characteristics and outcomes when applying the 2010 and 1987 criteria for rheumatoid arthritis. Ann. Rheum. Dis. 2011;71 (2): 238-41. doi:10.1136/annrheumdis-2011-200205 - Pubmed citation
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4. Zochling J, Brandt J, Braun J. The current concept of spondyloarthritis with special emphasis on undifferentiated spondyloarthritis. Rheumatology (Oxford). 2005;44 (12): 1483-91. doi:10.1093/rheumatology/kei047 - Pubmed citation
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5. Paramarta JE, De Rycke L, Ambarus CA et-al. Undifferentiated spondyloarthritis vs ankylosing spondylitis and psoriatic arthritis: a real-life prospective cohort study of clinical presentation and response to treatment. Rheumatology (Oxford). 2013;52 (10): 1873-8. doi:10.1093/rheumatology/ket239 - Pubmed citation
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