Bone mineral density in patients with symptoms suggestive of spondyloarthritis

Patients with axial spondyloarthritis (axSpA) have an increased risk of osteoporosis related to inflammation. We evaluate the performance of low bone mineral density (BMD) in diagnosis of axSpA for patients with symptoms suggestive of the disease. A low BMD (T ≤ -2) could be an additional tool for the diagnosis of axSpA.

Diagnosis of axial spondyloarthritis (axSpA) can be challenging, especially in the absence of radiographic abnormalities. Patients with axSpA have an increased risk of osteoporosis related to inflammation. This study evaluated the performance of low bone mineral density (BMD) in diagnosis of axSpA for patients with symptoms suggestive of the disease.

Medical files of patients that visited a tertiary centre for symptoms suggestive of axSpA were reviewed. Two hundred and sixty-seven patients were classified in confirmed axSpA or unconfirmed axSpA according to the diagnosis of a senior rheumatologist. BMD measurements results and percentage of patients with a low BMD (T ≤ -2) at either spine or hip were compared between the two groups. Diagnostic performances of low BMD (specificity, sensitivity, positive, negative predictive values and positive likelihood ratio (LR+)) were assessed.

Compared to patients with unconfirmed axSpA (n = 74), patients with confirmed axSpA (n = 193) had similar age, were more frequently male, with positive HLA B27, higher disease duration and higher C-reactive protein (CRP). Low BMD was more frequent at spine and hip, in patients with confirmed (40.3%) than unconfirmed axSpA (24.6%, p = 0.021). The LR+ of low BMD for an axSpA diagnosis was 2.60 and 3.12 at the spine and hip. In the subgroup of patients without any radiographic abnormalities (n = 128), the LR+ of low BMD for an axSpA diagnosis was 2.90 and 2.54 at the spine and hip.

In patients with symptoms suggestive of axSpA, a low BMD (T ≤ -2) could be an additional tool for the diagnosis of axSpA.