In patients with early axial spondyloarthritis (axSpA), clinical disease activity, magnetic resonance imaging (MRI) spinal inflammation, enthesitis, and age are determinants of impaired spinal mobility, according to study results published in RMD Open.

Researchers sought to evaluate the determinants of impairment in spinal and hip mobility in patients with early axSpA. They analyzed 5-year longitudinal data from the DEvenir des Spondyloarthrites Indifférenciées Récentes (DESIR) cohort. Study participants were aged between 18 and 50 years and had a recent onset (>3 months or <3 years) of inflammatory back pain that was indicative of axSpA. Patients with a definitive diagnosis of axSpA, according to the treating rheumatologist, at the end of follow-up (month 60), were selected for the study. Mobility was assessed using the linear definition of Bath Ankylosing Spondylitis Metrology Index (BASMI), ranked on a scale of 0 to 10, with higher scores denoting worse mobility.

Researchers analyzed data from 644 patients and 5152 visits. Higher BASMI scores were independently and positively associated with Ankylosing Spondylitis Disease Activity Score C-reactive protein (ASDAS-CRP; adjusted B, 0.21; 95% CI, 0.15-0.28), enthesitis score (adjusted B, 0.02; 95% CI, 0.01-0.04), Bath Ankylosing Spondylitis Radiology Index (BASRI)-hips (adjusted B, 0.65; 95% CI, 0.31-1.00), MRI spinal inflammation score (adjusted B, 0.11; 95% CI, 0.04-0.19), and age (adjusted B, 0.02; 95% CI, 0.01-0.03). Better mobility, as measured by BASMI, was related to body mass index (adjusted B, -0.04; 95% CI, -0.06 to -0.01) and human leukocyte antigen B27 (HLA-B27) positivity (adjusted B, -0.24; 95% CI, -0.41 to -0.08).

Overall, all BASMI components were independently associated with MRI spinal inflammation and ASDAS-CRP, except for maximal intermalleolar distance, which is indicative of hip mobility and not found to be linked to spinal inflammation on MRI.


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Study limitations included the fact that the Berlin MRI scoring system and the modified

Stoke AS Spinal Score may not assess the full spectrum of MRI or radiographic lesions and the lack of inclusion of inter- and intra-reader reliability of mobility measures. 

Researchers concluded that the results of this study support the widespread use of ASDAS, with this index demonstrating a good association with all BASMI components. The early treatment of clinical symptoms of axSpA, reversible spinal inflammation, and enthesitis may provide important benefits with regard to recovery of mobility and attainment of improved patient outcomes.

Reference

Carvalho PD, Ruyssen-Witrand A, Fonseca J, Marreiros A, Machado PM. Determining factors related to impaired spinal and hip mobility in patients with axial spondyloarthritis: longitudinal results from the DESIR cohort. RMD Open. 2020;6(3):e001356. doi:10.1136/rmdopen-2020-001356