High Prevalence of Asymptomatic Vertebral Fractures in Chinese Women with Systemic Lupus Erythematosus

Objective. To investigate the prevalence of vertebral fractures and to identify risk factors associated with vertebral fractures in Chinese women with systemic lupus erythematosus (SLE). Methods. One hundred fifty-two consecutive patients with SLE were recruited in this cross-sectional study. Bone mineral density (BMD) measurements of the hip and spine were performed using the same dual energy X-ray absorptiometry (DEXA). Lateral radiographs of the spine (T5-L4) were assessed for vertebral fractures using a method described by Genant. Inflammatory and biochemical markers included C-reactive protein, receptor activator of nuclear factor-kappa B ligand, serum B-CrossLaps assay for C-terminal telopeptides of type I collagen, and osteoprotegerin (OPG). Results. Asymptomatic vertebral fractures Occurred in 20.4% of patients with SLE. Univariate analyses of variables associated with fractures were older age, higher body mass index (BMI), lower BMD spine, lower BMD hips, higher serum C3 and C4, longer estrogen exposure, higher levels of OPG, and the use of sunscreen. Multivariate analysis showed older age (p = 0.017), higher BMI (p < 0.036), and lower BMD of the spine were significantly associated with vertebral fractures in the thoracic and/or himbar spine (odds ratio 1.068, 1.166. 0.005; p = 0.018, p = 0.025, p = 0.003, respectively). Conclusion. Asymptomatic vertebral fractures occur in 20.4% of patients with SLE and 30% of these patients have normal BMD. The Current method using DEXA to predict the presence of vertebral fracture has limited value and there is a need for assessment of bone quality. Vertebral morphometry in patients with SLE is recommended and early therapeutic intervention is necessary to prevent vertebral fractures in patients with SLE. (First Release July 15 2009; J Rheumatol 2009; 36:1646-52; doi: 10.3899/jrheum.081337)