The prevalence of vertebral fractures in spondyloarthritis: relation to disease characteristics, bone mineral density, syndesmophytes and history of back pain and trauma

Introduction: An increased risk of vertebral fracture (VF) is one of the extra-articular manifestations of spondyloarthropathy (SpA). The prevalence of moderate to severe VFs visualized by radiography (Rx) in patients with SpA in daily practice is unknown until imaging of the full spine is available, as most VFs do not present with clinical signs and symptoms of an acute fracture. Methods: We evaluated the prevalence of VFs (>25 % loss in height) on available Rx and dual-energy X-ray absorptiometry (DXA) images in 390 consecutive patients with SpA in daily practice. We assessed their association with disease characteristics, bone mineral density, the modified Stoke Ankylosing Spondylitis Spinal Score, and history of trauma. Results: Forty-six patients (11.8 %) had Rx VF (56.4 % men, 93.5 % in the thoracic spine), and 44.5 % had multiple VFs. Compared with patients without VF, patients with VF were older (52.2 vs. 47.3 years, p <0.01; range 25-84 years), had lower femoral neck T-scores (-1.1 vs. -0.7; p <0.05), and had a marginally higher modified Stoke Ankylosing Spondylitis Spinal Score (11.7 vs. 7.0; p = 0.06). Among patients with VFs, 15.2 % had a history of trauma with acute back pain (p <0.001 vs. no VF). The reliability of DXA for diagnosing radiographic VFs was high (kappa 0.90). Conclusions: Moderate to severe VFs are found in more than 10 % of patients with SpA before the age of 40 years in 5 % of women and 9 % in men. Most VFs are located in the thoracic region, are related to low femoral neck bonemineral density and to stiffening of the spine, and are only rarely related to trauma history. DXA is a useful alternative for diagnosing VFs.