Session Type: ACR Concurrent Abstract Session
Session Time: 9:00AM-10:30AM
Background/Purpose: The ASAS definition of a positive MRI is solely based on inflammation in the sacroiliac joints (SI), although spinal inflammatory lesions on MRI suggestive of axial Spondyloarthritis (axSpA) may also occur. It is not well established yet how often inflammation in the spine is present in absence of inflammation in the SI and consequently if it is useful to change the definition of a positive MRI to include inflammation in the spine. The aim is to analyze the prevalence of spinal inflammation on MRI in patients with chronic back pain at baseline, and to evaluate the yield of adding MRI-spine as imaging criterion in the ASAS classification criteria for axSpA.
Methods: The SPACE-cohort includes patients with chronic back pain (≥3 months, ≤2 years, onset <45 years) in six participating Rheumatology centers. All available baseline radiographs (X-SI), MRI of SI (MRI-SI) and spine (MRI-spine) were independently scored by 3 well-calibrated readers for each method. MRI-SI was scored according to the ASAS definition. Bone marrow edema suggestive of axSpA was assessed in the entire spine and only counted if visible on ≥2 consecutive slices. For the definition of a positive MRI-spine two cut-off values for inflammatory lesions were used: ≥3 inflammatory lesions (ASAS consensus definition) and ≥5 inflammatory lesions (defined as the optimal cut-off value). All modalities were considered positive if 2/3 readers agreed.
Results: All patients with X-SI, MRI-spine, and MRI-SI available at baseline (n=487) were included in the analysis. Of the 487 patients, 73 (15.0%) patients had a positive MRI-SI, of which 23/73 (31.5%) patients had a positive MRI-spine (≥3 inflammatory lesions) and 17/73 (11.4%) patients had a positive MRI-spine defined by ≥5 inflammatory lesions. In total, 50/414 (12.1%) and 18/414 (4.3%) patients with negative MRI-SI had a positive MRI-spine according to ≥3 and ≥5 inflammatory lesions, respectively. Addition of MRI-spine to the classification criteria by ≥5 inflammatory lesions would lead to classification of 16 additional patients via the imaging arm, with 8 patients already fulfilling the clinical arm. The newly classified patients (n=8) had a mean number (SD) of SpA-features of 1.5 (1.1) of whom 3/8 (37.5%) were HLA-B27 positive. Furthermore, one patient had inflammatory bowel disease and two patients were positive for peripheral arthritis. Most reported SpA-features were inflammatory back pain, good response to NSAIDs, and positive family history for SpA.
Conclusion: In this cohort, a positive MRI-spine in the absence of sacroiliitis on MRI was rarely seen. Addition of MRI-spine as an imaging criterion to the ASAS axSpA criteria had a low yield in number of classifications, and included mostly patients with a low probability of having axSpA. Therefore, performing MRI of the spine is of little value in the classification of patients with short duration CBP and suspicion of axSpA.
To cite this abstract in AMA style:Ez-Zaitouni Z, Bakker P, van Lunteren M, van den Berg R, Reijnierse M, Fagerli KM, Ramonda R, Landewé R, Jacobsson LTH, van Gaalen F, van der Heijde D. Adding MRI of the Spine to the ASAS Classification Criteria for Axial Spondyloarthritis, Redundant or Beneficial? Results from the Spondyloarthritis Caught Early (SPACE)-Cohort [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/adding-mri-of-the-spine-to-the-asas-classification-criteria-for-axial-spondyloarthritis-redundant-or-beneficial-results-from-the-spondyloarthritis-caught-early-space-cohort/. Accessed November 25, 2020.
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