An Important Consideration in Ankylosing Spondylitis

Jonathan Kay, MD


September 24, 2015

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Hello. I'm Dr Jonathan Kay, professor of medicine and director of clinical research in the Division of Rheumatology at UMass Memorial Medical Center in the University of Massachusetts Medical School, both in Worcester, Massachusetts.

Back pain is a common symptom among patients presenting to see a rheumatologist, but not all patients have mechanical back pain. In fact, 2-3 million individuals in the United States have inflammatory back pain. They present with back pain that is most pronounced upon first awakening, and it occasionally awakens them from sleep. Their pain improves as the day progresses and is better with exercise rather than worse.

Typically, inflammatory back pain evolves into evidence of sacroiliitis on plain radiographs. However, not all patients with axial spondyloarthritis (axSpA) have evidence of sacroiliac joint change that would meet the modified New York criteria for ankylosing spondylitis.

MRI is a more sensitive technique where evidence of osteitis is evident on short tau inversion recovery (STIR) images. This increased signal indicates inflammation in bone that is a precursor, in many cases, of sacroiliac joint destruction.

Currently, there is no tumor necrosis factor (TNF) inhibitor indicated by the US Food and Drug Administration (FDA) for the treatment of nonradiographic axSpA (nr-axSpA).

TNF inhibitors are a very effective treatment for inflammatory back pain patients who do not respond adequately to nonsteroidal anti-inflammatory drugs. However, TNF inhibitors are not available to patients with nr-axSpA in the United States.

In the European Union, adalimumab, etanercept, and golimumab have been approved for the treatment of nr-axSpA. However, because the FDA considers ankylosing spondylitis and nr-axSpA to be two different diseases, these agents are indicated only for treatment of patients who show evidence of sacroiliac joint destruction.

Since one third to one half of patients with nr-axSpA do not progress to develop plain radiographic evidence of sacroiliitis, it is important that we consider this syndrome as a spectrum of disease.

AxSpA can include patients with both nonradiographic and radiographic disease. In future studies of disease-modifying drugs and biologic agents, it is important that we be inclusive of all patients with axSpA so that we can offer effective therapies to everyone.

I thank you for your attention and look forward to seeing you again on Medscape.


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