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With proper application of any strategy described here, a rheumatologist will need to see 2 to 3 patients with chronic back pain to identify one patient with axSpA. Specific aspects of uveitis and the presence of non-radiographic axSpA are helpful clues.
Chronic inflammatory back pain is a hallmark of axial spondyloarthritis (axSpA) but not every patient with back pain will have axSpA. Trouble is, it’s often hard to distinguish which patients may be at greatest risk for actually having this disorder.
As many as 25% of people in the general population have chronic back pain, but only 5% of them turn out to have axSpA. While there are specific criteria for axSpA, many patients continue to be inappropriately referred to rheumatologists, notes a recent review of screening strategies published online in Clinical Rheumatology.
Conversely, studies show that 24% of patients who fulfill the criteria for axSpA may not be recognized by rheumatologists -- and half of axSpA patients have non-radiographic disease, the reviewers comment.
The Assessment of SpondyloArthritis International Society (ASAS) classification criteria plus MRI helps diagnose many axSpA patients before there’s radiographic evidence of disease.
Still, there’s a “significant” delay of 8 to 11 years in the diagnosis of axSpA, comment Atul A. Deodhar, MD, Professor of Medicine at the Oregon Health Sciences University in Portland and Abhijeet Danve, MD, a Research Fellow at the University of Nebraska Medical Center, authors of the review.
Even though axSpA is as prevalent as RA, awareness of the disorder is much lower in the medical community, they note. So steps are clearly needed in screening patients.
Teasing apart specific aspects of classification criteria and educating those providers most likely to refer patients –- pain specialists, physical therapists, for example -– may enable more axSpA patients to be correctly referred, so diagnosis and treatment can begin earlier.
Eyes on the Criteria
Inflammatory back pain is one of the most common reasons for referral, notes the review, but IBP by itself is non-specific; less than a third of axSpA patients can be identified using this single criteria -- so IBP should be only one of several parameters.
Current criteria for axSpA include chronic back pain for more than 3 months in people younger than age 45 with one or more typical spondyloarthritis features (eg, sacroiliitis seen on imaging).
Even using these criteria, only 35% to 45 % of patients referred to rheumatologists by other clinicians are found to have axSpA.
Adding HLA-B27 testing and other factors doesn’t change that picture much.
"The presence of HLA-B27, family history of AS or axSpA, good response to NSAIDs, and extra-articular manifestations of SpA (psoriasis, inflammatory bowel disease, and uveitis)... Enthesitis, dactylitis, and inflammatory arthritis have high specificity but low sensitivity and, hence, may not be very useful for screening,” comment Danve and Deodhar.
“It’s likely premature to use extensive genetic testing (other than HLA-B27) for diagnosis,” add the authors of a second online in Clinical Rheumatology, examining biomarkers for axSpA. “The problem is that no individual biomarkers have been reproducibly shown to assess disease activity or predict outcome” -- much less have specificity in making a diagnosis.
What would be useful additions?
Specific aspects of uveitis and the presence of non-radiographic axial spondyloarthritis (nr-axSpA) may help better distinguish patients with possible axSpA.
“The ‘phenotype’ of the uveitis characteristic of ankylosing spondylitis (sudden onset, anterior, unilateral, recurrent, more often male) may differ from the phenotype often seen with either psoriatic arthritis or inflammatory bowel disease (insidious onset, anterior and intermediate, bilateral, chronic, and/or more often female),” say the authors of another online study in the same issue of Clinical Rheumatology.
Increased awareness of those factors among non-rheumatologists as well as rheumatologists would aid diagnosis and enable better referrals.
“Patients with acute anterior uveitis and inflammatory bowel disease have a much higher risk of developing axSpA compared to general population, so those patients with these diseases could be potential candidates for screening for presence of axSpA in ophthalmology and gastroenterology clinics. Also, patients with psoriasis have a 30% chance of developing psoriatic arthritis, and a large percentage of these are at an increased risk of developing axSpA,” note Danve and Deodhar.
Traditional notions that women are less likely to have axSpA should be discarded, they say.
“It has been recognized that women develop nr-axSpA with the same frequency as men, but they less commonly progress to radiographic disease,” they write. “Therefore we feel it is important to educate the referring providers regarding women being equally at risk as men in developing axSpA so that both men and women with chronic back pain will be appropriately screened.”
1. Danve A, Deodhar A. Screening and referral for axial spondyloarthritis-need of the hour. Clinical Rheumatology. 2015;34(6):987-0993.Online: 07 May 2015. DOI 10.1007/s10067-015-2958-2 http://link.springer.com/article/10.1007/s10067-015-2958-2
2. Reveille JD. Biomarkers for diagnosis, monitoring of progression, and treatment responses in ankylosing spondylitis and axial spondyloarthritis. Clinical Rheumatology. 2015;34(6):1009-1018. Online 05 May 2015. DOI 10.1007/s10067-015-2949-3 http://link.springer.com/article/10.1007/s10067-015-2949-3
3. Rosenbaum JT. Uveitis in spondyloarthritis including psoriatic arthritis, ankylosing spondylitis, and inflammatory bowel disease. Clin Rheumatol. 2015;34(6):999-1002 May 8. http://link.springer.com/article/10.1007/s10067-015-2960-8 Online 05 May 2015. DOI 10.1007/s10067-015-2960-8. http://link.springer.com/article/10.1007/s10067-015-2960-8