Baseline MRI inflammation is not a determinant of 5-year bone mineral density loss in patients with early spondyloarthritis

• Half of patients have a BMD loss at any site at 5 years. • Baseline MRI inflammation is not associated with 5 year-BMD loss in early SpA patients. • TNF blockers have protective effect on bone loss at 5 years. The aim of this study was to assess the effect of baseline inflammation on Magnetic Resonance Imaging (MRI) on the change in Bone Mineral Density (BMD) over 5 years in patients with early spondyloarthritis (SpA). From the patients of the DESIR cohort (an early axial SpA cohort), patients with BMD data at both baseline and 5 years, and baseline spine and sacroiliac joints MRI were included. Inflammation was assessed with the SpondyloArthritis Research Consortium of Canada (SPARCC) spine score. Significant BMD loss was defined by a change of > 0.03 g/cm 2 . No patients had received TNF blockers before inclusion in the cohort. Univariate and multivariable prognostic analyses were performed. An inverse propensity score weighting method was used to handle confounders. One hundred and eighty-three patients were included (mean age 33.9 ± 8.7 years, 58.5% men). A significant bone loss was reported in 51% ( n = 92) of patients at either lumbar spine or hip. Fourteen (7%) patients had low BMD (Z-score < −2) at the end of the follow-up vs. 28 (15%) at baseline. In multivariable analysis, age was a protective factor of 5 year-BMD loss at any site (OR = 0.96, 95% CI [0.93–0.99]). Baseline MRI inflammation has no significant effect on BMD change at any site (OR= 0.84, 95% CI [0.46–1.53]). Half of patients with early SpA have a significant bone loss at either lumbar spine or hip over 5 years. Baseline MRI inflammation is not a determinant of this bone loss.