The Association Between Age and Clinical and Radiological Activity in Axial Spondyloarthritis

Objective: To investigate the associations between age and clinical and radiological disease activities in axial SpA. Methods: One hundred and twenty-one patients fulfilling the Assessment of SpondyloArthritis International Society Classification Criteria for axial SpA were included in analyses. Patient demographics, disease activity and radiographic scores, as well as magnetic resonance imaging (MRI) with diffusion weighted imaging derived apparent diffusion coefficient values (DWI(ADC)), were compared between patients aged > 40 and [Formula: see text] 40 years at a cross-sectional level. Variables with significant differences in univariate analyses were used as dependent variables in multivariate linear regression models adjusted for potential confounding/contributing factors. Results: Multivariate analysis showed that increasing age was significantly associated with higher Bath Ankylosing Spondylitis Functional Index (B = 0.04, p < 0.01) and Bath Ankylosing Spondylitis Metrology Index scores (B = 0.04, p < 0.01); as well as higher modified Stoke Ankylosing Spondylitis Spine Score (B = 0.41, p < 0.01). On MRI, increasing age was associated with a lower DWI(ADC) (B = (-0.01), p < 0.01) of the SI joints, but higher DWI(ADC) values of the axial spine (B = 0.01, p = 0.01). Conclusion: Increasing age in SpA was associated with greater functional impairment and structural damage, more inflammation of the axial spine, but less inflammation of the SI joints. Our findings are consistent with the traditional belief that SpA is an “ascending disease” and highlights the importance of different modalities of MRI in the diagnosis and disease monitoring of SpA.