ASAS Definition for Positive MRI-Sacroiliitis Effective for axSpA Recognition

ankylosing spondylitis
ankylosing spondylitis
The definition of a positive MRI-sacroiliitis is effective for recognizing axial spondyloarthritis and is better than the definition for a positive MRI-spine.
This article is part of Rheumatology Advisor’s 2017 in-depth coverage of ACR, which took place in San Diego, CA. Our staff will be reporting on the latest treatment advancements and research initiatives for spondyloarthritis. Click here to read more of Rheumatology Advisor‘s conference coverage.

SAN DIEGO — The definition of a positive magnetic resonance image (MRI)-sacroiliitis attributed by the Assessment of Spondyloarthritis International Society (ASAS) is effective for recognizing axial spondyloarthritis (axSpA) and is better than the definition for a positive MRI-spine, according to a study presented at the American College of Rheumatology 2017 Annual Meeting, held November 3-8 in San Diego, California.

According to the investigators of this study, “[O]nly scarce data are available regarding the prevalence of MRI inflammatory lesions of the sacroiliac joints (SIJ) or the spine suggestive of [axSpA] in patients with recent onset mechanical chronic back pain.”

Study investigators examined MRIs of the SIJ and spine of non-axSpA patients with chronic back pain (n=98), specifically evaluating the presence of inflammatory lesions indicative for axSpA. Investigators compared these data with MRIs of patients with a recent axSpA diagnosis (n=100). Investigators obtained a cohort matched for age.

Among MRIs of the SIJ, significantly more patients with axSpA vs non-axSpA had at least 1 inflammatory lesion (40.0% vs 25.3%, respectively; P =.028). The investigators found that the MRI-sacroiliitis attributed by the ASAS had high specificity and a positive likelihood ratio for axSpA. Irrespective of the applied definition of a positive MRI for the SIJ, performances were poor and presented with positive likelihood ratios <2.

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The investigators believe that these findings support “the idea of not including a positive MRI of the spine in the ASAS classification criteria.”

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Molto A, Gossec L, Foltz V, et al. Inflammatory lesions of the sacroiliac joints, but not of the spine, are of high utility for recent onset axial spondyloarthritis recognition. Presented at: American College of Rheumatology (ACR)/Association of Rheumatology Health Professionals (ARHP) Annual Meeting; November 3-8, 2017; San Diego, CA. Abstract 588.