Abstract
Objective To investigate whether the trabecular bone loss is longitudinally associated with disease activity measures in patients with axial spondyloarthritis (axSpA).
Methods Data from patients enrolled in the Incheon Saint Mary’s axSpA prospective observational cohort were evaluated. Trabecular bone loss was assessed using the trabecular bone score (TBS). The relationship between TBS and disease activity measures (Ankylosing Spondylitis Disease Activity Score [ASDAS], Bath Ankylosing Spondylitis Disease Activity Index [BASDAI], erythrocyte sedimentation rate [ESR], and c-reactive protein [CRP]) was investigated using generalized estimating equations (GEE) models.
Results Four year follow-up data from 240 patients (80% males, mean age 37 ± 12 years) were evaluated. At baseline, higher disease activity according to ASDAS-ESR and ASDAS-CRP showed a trend towards lower TBS (p = 0.003 and p = 0.016, respectively). The univariate GEE analyses showed a significant association between TBS and disease activity measures over time, with the exception of BASDAI. Univariate analysis showed a longitudinal association between TBS and age, smoking, and spinal structural damage. In the multivariate GEE analysis, ASDAS-ESR, ASDAS-CRP, ESR, and CRP were longitudinally associated with TBS after adjusting for confounding factors. ASDAS scores and inflammatory markers were longitudinally associated with TBS in patients with ankylosing spondylitis (AS, 79%), but not in patients with nonradiographic axSpA (nr-axSpA). BASDAI showed no relationship with TBS in either the AS or nr-axSpA groups.
Conclusion Trabecular bone loss in axSpA patients, as assessed using the TBS, shows a longitudinal association with ASDAS scores and inflammatory markers.