Background In patients with axial spondyloarthritis (axSpA), the relationship between inflammatory lesions on MRI and clinical disease activity (DA) measures is still unclear, especially at the early stages of the disease.
Objectives To investigate the relationship between inflammatory lesions in sacroiliac joints on magnetic resonance imaging (MRI-SI) and clinical disease activity measures in patients with axSpA.
Methods Patients with inflammatory back pain of maximum 3 years and suspicion of SpA by the rheumatologist were included in the DESIR cohort. Two-year follow-up data from 474 patients fulfilling ASAS axSpA criteria with MRI-SI at baseline, 1- and 2-years were analysed. The relationship between MRI-SI (SPARCC) and ASDAS, BASDAI, patient's global DA, night pain, CRP and ESR was investigated using cross sectional (correlation-coefficients at baseline) and longitudinal (GEE using 2-year follow-up data) analyses. Model fit was assessed with the QIC.
Results The relationship between clinical DA measures and MRI-SI was shown to be different for males and females and analyses are therefore presented stratified for gender. Cross-sectional analysis: In males, a significant positive correlation with MRI-SI was found for ASDAS (r =0.19), ESR (r=0.31) and CRP (r=0.36) but not for BASDAI or pain. In females, a positive correlation was found for ESR and CRP at baseline while negative correlations were found for the remaining measures. Longitudinal analysis: In males, a statistically significant relationship with MRI-SI was found for all clinical DA measures except BASDAI (Table); ASDAS (beta parameter estimate (95%CI): 2.41 (1.13-3.69), pain at night: 0.50 (0.04-0.95) and global DA assessment: 0.45 (0.06-0.84), ESR: 0.18 (0.01-0.35) and CRP: 0.15 (0.03-0.28)]. In females, there was no significant relationship.
Conclusions In patients with axSpA, inflammation on MRI-SI is related to clinical disease activity measures only in males. Moreover, the measures that best relate to MRI are acute phase reactants and ASDAS.
Disclosure of Interest None declared