Prevalence and risk factors of vertebral compression fractures in female SLE patients

INTRODUCTION: Our objective was to determine the frequency of and factors associated with prevalent vertebral compression fractures in female systemic lupus erythematosus (SLE) patients attending rheumatologists in western Sweden. METHODS: In this cross sectional study 150 women were included. They were examined with x-ray of thoracic and lumbar spine (Th4 to L4). A reduction of at least 20% of any vertebral height, assessed by Genant's semiquantitative method, was defined as a fracture. Bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (DXA). RESULTS: Median patient age was 47 years (20 to 82) and disease duration 11 years (1 to 41). Only 6 (4%) women had a history of clinical compressions whereas 43 (29%) had at least one radiological fracture each. The patients with at least one fracture at any site were characterized by older age (P < 0.001), being postmenopausal (P < 0.01), higher Systemic Lupus International Collaborative Clinics Damage Index (P < 0.05), lower BMD total hip and femoral neck (P < 0.05), more peripheral fractures (P < 0.01), medication with bisphosphonates (P <0.05) and calcium and vitamin D3 (P < 0.05). There were no significant differences regarding current or cumulative glucocorticosteroid dose between the groups. In logistic regression analyses high age remained as a risk factor of at least one vertebral fracture at any site whereas low BMD in total hip was associated with vertebral fracture in the lumbar spine. CONCLUSIONS: Radiological compression fractures are common but seldom diagnosed in SLE patients. High age and low BMD in total hip, but not in spine, was associated with vertebral fractures.