A low prevalence and incidence of vertebral fractures has been reported in a cohort of patients with early spondyloarthritis (SpA), according to the results of a longitudinal prospective study that were published in the Annals of the Rheumatic Diseases.

The researchers sought to evaluate the incidence of radiographic vertebral fractures over 5 years in patients with early SpA. They theorized that the prevalence of vertebral fractures in this population is lower than the prevalence reported in prior studies, particularly in patients with early disease. The study enrolled patients from the DESIR cohort with inflammatory back pain, which is highly suggestive of axial SpA. All radiographs from the DESIR cohort were assessed at a central facility by a single investigator. The prevalence and incidence of vertebral fractures, along with vertebral deformities, at baseline and 5 years were assessed.

A total of 708 patients with inflammatory back pain that was highly suggestive of axial SpA were included in the study. Overall, 694 patients had spinal x-rays at baseline; 432 also had x-rays at the 5-year visit. Average participant age was 34.3±8.7 and 53% were women.

The diagnosis of vertebral fracture was doubtful and needed adjudication in 19 participants (4.4%) and prevalent vertebral fractures were observed in 13 (3.0%), which were located at the thoracic spine. Of these, 12 were grade 1.

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At 5 years, 5 participants (1.15%) experienced an incident vertebral fracture. In these patients, 7 vertebrae were fractured, which were located mainly at the thoracic spine (6 of 7) and were mostly grade 1 (6 of 7).

The investigators concluded that the low prevalence and incidence of vertebral fractures reported in this cohort of patients might be explained by the differences in the characteristics of the population and the methods used for vertebral fracture assessment. Since deformities of vertebral bodies are frequent in patients with axial SpA, especially at the thoracic spine, some of these deformities may be misinterpreted as a fracture, leading to an overestimation of fracture prevalence. These findings should be taken into consideration when establishing a diagnosis of vertebral fracture.

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Reference

Sahuguet J, Fechtenbaum J, Molto A, et al. Low incidence of vertebral fractures in early spondyloarthritis: 5-year prospective data of the DESIR cohort [published online November 2, 2018]. Ann Rheum Dis. doi:10.1136/annrheumdis-2018-213922