Associations between spondyloarthritis features and MRI findings: A cross-sectional analysis of 1020 patients with persistent low back pain

OBJECTIVES: The Assessment of SpondyloArthritis international Society (ASAS) has previously published criteria for spondyloarthritis (SpA). The objectives in the current study were in a low back pain (LBP) cohort, including an unknown proportion of SpA patients, to: 1) estimate the prevalence of clinical features and MRI findings included in ASAS criteria, and 2) explore the associations between clinical features and MRI findings.

METHODS: Patients aged 18-40 years with persistent LBP referred to an outpatient spine clinic were included. Information on clinical features (incl. HLA-B27 and CRP) and MRI findings of the spine and sacroiliac joints (SIJ) were collected.

RESULTS: Of 1020 included patients, 537(53%) had minimum one clinical feature. Three clinical features were common; inflammatory back pain, good response to NSAID and family disposition (15-17% each). MRI sacroiliitis, according to ASAS definition, was present in 217(21%) patients. Of those, 91(42%) had bone marrow oedema (BMO) at the minimum requirement according to ASAS (low BMO score). HLA-B27, peripheral arthritis, good response to NSAID, and preceding infection associated independently with SIJ MRI findings (OR range 1.9-9.0). The remaining eight clinical features did not associate positively with MRI-findings. Importantly, only age associated independently with low BMO score at the SIJ (OR 1.1 per year).

CONCLUSION: In this population, 53% had minimum one clinical feature and 21% had sacroiliitis according to ASAS; furthermore, the associations between the clinical and imaging domains were inconsistent. The results indicate a need for further investigation of the importance of these findings in spondyloarthritis, including investigation of the minimum requirements for defining MRI sacroiliitis. This article is protected by copyright. All rights reserved.