Nonradiographic axSpA remains under-reported, underdiagnosed in the US
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Nonradiographic axial spondyloarthritis may be under-diagnosed in the U.S. because inflammatory back pain, a key component of this condition, is often not diagnosed appropriately, according to data presented at the virtual ACR State-of-the-Art Clinical Symposium.
“The prevalence of chronic back pain in the U.S. is nearly 20%,” John Reveille, MD, of The University of Texas Health Science Center at Houston, said in his presentation. “But the overwhelming majority of patients with chronic back pain are never actually seen by a rheumatologist.”
The clinical community, including rheumatology, is still learning about nonradiographic axial spondyloarthritis, according to Reveille. These patients experience chronic inflammatory back pain that begins before age 45 but does not appear as sacroiliitis on imaging. While more men experience radiographic axial spondyloarthritis, also known as ankylosing spondylitis, women are more likely to fall into the nonradiographic category.
Reveille cited data from the 2009-2010 National Health and Nutrition Examination Survey (NHANES) showing that 89.1% of 5,103 people surveyed had back pain, 19.4% had chronic back pain, and many of them aged in their 20s and 30s with chronic inflammatory back pain. “This is a huge problem,” he said.
Despite these prevalence rates, other parameters of spondyloarthritis, such as HLA-B27 mutation or sacroiliitis on imaging, were more likely than inflammatory back pain to have a patient referred to rheumatology. “Basically, inflammatory back pain was not previously a high prevalence of referral to rheumatology,” Reveille said.
There is a large body of information on back pain in the primary care, pain management and orthopedics literature, but with one large gap, according to Reveille. “This concept of inflammatory back pain is localized to the rheumatology community,” he said, and added that these other specialties do not “even consider inflammatory back pain as an independent entity.”
Reveille then explained why this is a problem for patients with nonradiographic axial spondyloarthritis. “Insurance data show that only 14.1% of people who sought a doctor for back pain have seen a rheumatologist,” he said. “It gets worse in patients aged 21 to 44, which is the age spondylitis is most likely to occur, where only 9% of those patients have seen a rheumatologist.”
In short, patients with possible nonradiographic axial spondyloarthritis are likely not receiving appropriate care.
That said, a number of questions about nonradiographic axial spondyloarthritis remain unanswered. The most important of these is whether nonradiographic patients will ultimately progress to radiographic disease at all, or whether the nonradiographic and radiographic disease states are independent entities.
Another question pertains to progression. Reveille suggested that some data may indicate that it can take 10 years for a patient to progress from inflammatory back pain to sacroiliitis on imaging, but even he believes that time is not necessarily a factor. “A number of cohorts have shown that male sex and elevated C-reactive protein were the best predictors of who would go on to develop radiographic axSpA,” he said.
All of this leads to a conclusion from a study published in The Permanente Journal by Curtis and colleagues, who suggested that there is “substantial under-recognition of these conditions in standard rheumatology clinical practice,” Reveille said.
Reference:
Reveille JD. Nonradiographic Spondyloarthritis in Your Clinic. Presented at: American College of Rheumatology State-of-the-Art Clinical Symposium. May 16-17, 2020 (virtual meeting).
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