Prevalence of and risk factors for low bone mineral density and vertebral fractures in patients with systemic lupus erythematosus

OBJECTIVE: To examine the prevalence of and risk factors for low bone mineral density (BMD) and vertebral fractures in patients with systemic lupus erythematosus (SLE). METHODS: We studied 107 SLE patients. Demographic and clinical data were collected, and radiographs of the thoracic and lumbar spine and BMD measurements by dual x-ray absorptiometry were performed. Vertebral deformities were scored according to the method of Genant et al: fractures were defined as a reduction of > or = 20% of the vertebral body height. Osteoporosis was defined as a T score less than -2.5 SD and osteopenia as a T score less than -1.0 SD in at least 1 region of measurement. RESULTS: Osteopenia was present in 39% of the patients and osteoporosis in 4% (93% female; mean age 41.1 years). In multiple regression analysis, low BMD in the spine was associated with a low body mass index (BMI), postmenopausal status, and 25-hydroxyvitamin D deficiency. Low BMD in the hip was associated with low BMI and postmenopausal status. At least 1 vertebral fracture was detected in 20% of the patients. Vertebral fractures were associated with ever use of intravenous methylprednisolone and male sex. CONCLUSION: Risk factors for low BMD in SLE patients are low BMI, postmenopausal status, and vitamin D deficiency. While osteoporosis defined as a low T score was found in only 4% of the patients, osteoporotic vertebral fractures were detected in 20%. The high prevalence of low BMD and vertebral fractures implies that more attention must be paid to the prevention and treatment of osteoporosis and fractures in SLE.