The prevalence of vertebral fractures in mild ankylosing spondylitis and their relationship to bone mineral density

Open Access
Publisher Website
Google Scholar
Abstract
Objective. To determine bone mineral density (BMD) in patients with mild ankylosing spondylitis (AS), to establish the prevalence of vertebral fractures and fracture risk in these patients, and to determine the relationship between BMD and vertebral fractures. Methods. Sixty-six men with mild AS were studied. BMD of the lumbar spine and femoral neck was measured by dual X-ray absorptiometry (DXA) and radiographs of the thoracic and lumbar spine were obtained in all subjects. From the radiographs, vertebral fractures were characterized by a morphometric technique using established criteria. Thirty-nine healthy male subjects aged 50–60 yr, recruited from primary care registers, had spinal radiographs performed and served as controls for vertebral fractures. Results. In patients with AS, BMD was reduced in both the lumbar spine 0.97 (0.1) g/cm2 [T score −1.10 (1.3), 95% confidence interval (CI) −0.50, +0.14] and femoral neck 0.82 (0.1) g/cm2 [T score −1.40 (1.2), 95% CI −0.51, +0.09]. There was no correlation between BMD of either the lumbar spine or femoral neck and duration of disease in patients with AS. Eleven of 66 (16.7%) patients with AS had a vertebral fracture, compared with one of 39 (2.6%) controls; odds ratio 5.92 (95% CI 1.4, 23.8). AS patients with fractures were not significantly older (mean age 41.4 vs 37.8 yr, P=0.17), but had significantly longer disease duration (12.4 vs 9.3 yr, PConclusions. Spinal and hip osteopenia and vertebral fractures are a feature of mild AS. However, there was no correlation between BMD and vertebral fractures in these patients. AS patients with mild disease had a higher risk of fractures compared with the normal population and this increased with the duration of disease.