“We define AS [ankylosing spondylitis] when there is radiographic evidence of sacroiliitis,” Dr. Khan said. “But that has been one of the most important reasons why this disease is not diagnosed for about five to nine years. That delayed diagnosis is totally unacceptable.”
He said there’s a need for better recognition of axial SpA by rheumatologists in the U.S.
A 2013 study found that 124 out of 514 patients, or 24%, who were between 18 and 44 years old and were seen with chronic back pain, actually had axial SpA but were undiagnosed by rheumatologists even though they met the criteria of the Assessment of SpondyloArthritis International Society.7
A recent study using data from the National Health and Nutrition Examination Survey found an overall prevalence of axial SpA to be 0.9% to 1.4% in the U.S.8
“These diseases are at least as common, if not more common, than rheumatoid arthritis,” he said. “We see many more patients with rheumatoid arthritis [than] we see with spondyloarthritis. The reason is ascertainment bias. These patients don’t come to see us.”
Another, older study concluded that 5% of chronic back pain sufferers may have AS or a mild form of AS that might never progress to definite ankylosis, but for whom treatment as if they have AS would be of benefit.9
Dr. Khan said we need to develop different strategies, such as a simple referral model used in Germany. There, someone with chronic back pain, with the first symptoms arising at age 45 or earlier, and for whom there are signs that the pain is inflammatory is referred immediately to a rheumatologist. That way, patients at risk of AS get into the proper hands more quickly.
“Let the rheumatologist decide what kind of imaging should be done, when and if testing for HLA-B27 is needed,” Dr. Khan said.
In a Dutch model, more red flags are considered, and preselection by primary care providers is recommended if a combination of at least three features from a menu of symptoms are present.
The longer disease goes undiagnosed and untreated, the worse the prospects for a better outcome.
“In the individual patient the effect of anti-TNF therapy on radiographic progression depends on the relative number of ‘acute’ vs. ‘mature’ inflammatory lesions,” Dr. Khan said. “Early diagnosis is a prerequisite for advances in disease modification. The earlier you control the disease, the earlier you treat osteitis, then that transformation into the osteoproliferative phase may not occur, and, therefore, one would prevent spine fusion,” he said.
