Diagnosing axSpA and AS in Primary Care

Primary healthcare providers often treat patients who suffer from rheumatic diseases, but as generalists, they can easily miss the signs for axial spondyloarthritis (axSpA) and ankylosing spondylitis (AS) and with a delayed diagnosis, comes delayed treatment.

In this article, we feature a review published in the June 30 issue of the New England Journal of Medicine in which Robert A. Colbert, M.D., Ph.D., a senior investigator with the National Institutes of Health, and colleagues, discuss the diagnosis and treatment of spondyloarthritis (axSpA) and ankylosing spondylitis (AS). Diagnosis is not always straightforward, they wrote.

“No single clinical feature, laboratory test or imaging result is either necessary or sufficient for the diagnosis. Referral to a rheumatologist should be considered for adolescents and young adults with unexplained back pain with a duration of more than 3 months,” the authors wrote.

Ankylosing spondylitis is an uncommon but well-established cause of chronic back pain. In its severest form, it can lead to the bony fusion of the vertebral joint. Ankylosing spondylitis is considered to be a subset of the broader and more prevalent axial spondyloarthritis, which affects the spine, pelvis and thoracic cage.

Few people who suffer from chronic low back pain in general have spondyloarthritis - approximately 0.9 to 1.4% of adults in the United States. And, only a subset of ankylosing spondylitis patients have inflammatory back pain (70-80%).

The symptoms usually begin with a dull inflammatory pain deep in the lower back or buttocks. It is often accompanied by morning back stiffness of 30 minutes or more, which diminishes with movement, but returns with inactivity. Some patients also have pain in the thoracic and cervical spine and more than 40% of patients report pain the chest, which often leads to unnecessary diagnostic tests for cardiovascular disease that could have been avoided had the source of pain been accurately diagnosed.

Classification Criteria

In 2009, the Assessment of SpondyloArthritis international Society (ASAS) penned classification criteria for axial spondyloarthritis that was based on imaging, clinical and laboratory criteria. The ASAS criteria addressed two subsets - nonradiographic axial spondyloarthritis and classic ankylosing spondylitis (i.e., radiographic axial spondyloarthritis).

The criteria for diagnosis included back pain for more than three consecutive months before 45 years of age; the presence of sacroiliitis confirmed on MRI or plain radiography, and at least one clinical or laboratory finding characteristic of spondyloarthritis. Or, the determination can be based on a positive result for HLA-B27 plus two clinical features of spondyloarthritis.

The role of imaging

MRIs are highly recommended. This technology can detect inflammation in the sacroiliac joints in patients with symptoms of ankylosing spondylitis "even when these joints do not appear to be abnormal on conventional radiography."

Plain radiography is recommended for the diagnosis of ankylosing spondylitis in patients with back pain for three months or more and who also have one or more clinical criteria.

Tools for assessing disease activity

The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Bath Ankylosing Spondylitis Functional Index (BASFI) are self-administered patient questionnaires. Other analysis tools include the Bath Ankylosing Spondylitis Metrology Index (BASMI), which is used to assess spinal mobility; and the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS), which is used to assess radiographic damage. The Ankylosing Spondylitis Disease Activity Score (ASDAS) has been adopted more recently.

Physical manifestations

Arthritis in peripheral joints or peripheral entheses is present in up to half of patients with ankylosing spondylitis. Peripheral arthritis, enthesitis, or dactylitis can also indicate spondyloarthritis with little or no axial involvement.

Acute anterior uveitis can occur in 30-40% of ankylosing spondylitis throughout their life.

Treatment goals

Treatment goals include reducing symptoms, improving and maintaining spinal flexibility and normal posture, reducing functional limitations, maintaining the ability to work, and decreasing the complications associated with axial spondyloarthritis.

For pain and stiffness, the first-line of treatment are NSAIDs, including selective inhibitors of cyclooxygenase 2. When NSAIDs fail, TNF inhibitors such as infliximab, etanercept, adalimumab, golimumab and certolizumab are recommended. TNF inhibitors have been associated with rapid, profound and sustained improvement for patients.

[[{"type":"media","view_mode":"media_crop","fid":"49844","attributes":{"alt":"","class":"media-image","id":"media_crop_9622663953697","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"6059","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","title":" ","typeof":"foaf:Image"}}]]

References:

"Ankylosing Spondylitis and Axial Spondyloarthritis."

 Joel D. Taurog, M.D., Avneesh Chhabra, M.D., and Robert A. Colbert, M.D., Ph.D.N Engl J Med 2016; 374:2563-2574June 30, 2016DOI: 10.1056/NEJMra1406182