Baseline MRI Inflammation Not a Determinant of BMD Loss in Spondyloarthritis

A majority of patients with early axial spondyloarthritis (SpA) experience significant loss of bone mineral density (BMD) at the lumbar spine or hip over 5 years, which is not attributed to inflammation at baseline magnetic resonance imaging (MRI), according to study results published in Joint Bone Spine.¹

Osteoporosis at the spine and hip is prevalent in early SpA. Results from an earlier cross-sectional study of patients with early axial SpA showed that inflammation of the spine diagnosed by bone marrow edema on MRI was significantly associated with low BMD at the spine and hip.²

The objective of this study was to assess the effect of baseline inflammation on MRI on 5-year changes in BMD in early SpA.

Researchers evaluated data of 183 patients (mean age, 33.9±8.7 years; 58.5% men) from the DEvenir des Spondylarthrites Indifférenciées Récentes (DESIR) cohort who had BMD measurements at baseline and at 5 years, as well as baseline MRI assessment. At baseline, researchers collected information about patients’ age, body mass index, osteoporosis risk factors, Bath Ankylosing Spondylitis Disease Activity Index, Ankylosing Spondylitis Disease Activity Score, and ongoing treatments. Patients also underwent an MRI of the spine and sacroiliac joints, and inflammation of these areas were assessed using methods from the SpondyloArthritis Research Consortium of Canada. 

Researchers defined significant loss of BMD as a decrease >0.03 g/cm² between baseline and 5 years. They performed the main analysis using univariate and multivariate logistic regressions and inverse propensity score weighting for secondary analysis.

Results indicated low BMD at baseline at any site in 28% of patients (n=15) and inflammation on MRI in 63% of patients (n=115). At 5 years, 51% of patients (n=92) experienced significant bone loss at either the lumbar spine or hip, and 7% of patients (n=14) had low BMD. The main analysis showed that age was the single variable with a protective effect against 5-year BMD loss at any site (odds ratio [OR], 0.96; 95% CI, 0.93-0.99). Baseline MRI inflammation was not associated with BMD loss at any site at 5 years (OR, 0.84; 95% CI, 0.46-1.53; P =.70). 

Study limitations included a low number of patients with BMD measurements at baseline and 5 years, despite the large size of the initial DESIR cohort (n=708); the lack of exclusion of selection bias; the lack of quality control of BMD measurements, and the hypothesis that changes in BMD may be related to change in MRI inflammation over time.

Study researchers concluded that 51% of patients with early axial SpA experience loss of BMD at any site at 5 years, and baseline MRI inflammation is not a determinant of BMD loss.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

References

1. Fechtenbaum M, Molto A, Roux C, Goupille P, Chevret S, Briot K. Baseline MRI inflammation is not a determinant of 5-year bone mineral density loss in patients with early spondyloarthritis [published online October 10, 2019]. Joint Bone Spine. doi:10.1016/j.jbspin.2019.09.016

2. Briot K, Durnez A, Paternotte S, Miceli-Richard C, Dougados M, Roux C. Bone edema on MRI is highly associated with low bone mineral density in patients with early inflammatory back pain: results from the DESIR cohort. Ann Rheum Dis. 2013;72:1914-1919.