Prevalence and risk factors of osteoporosis in female SLE patients-extended report

To determine the frequency of osteoporosis and possible risk factors of low bone mineral density (BMD) in women with systemic lupus erythematous (SLE) in western Sweden. In addition, to evaluate if adequate anti-osteoporotic treatment was provided.

BMD was measured at radius, lumbar spine and hip by dual X-ray absorptiometry (DXA). An 'expected' control BMD was calculated for each patient. Simple and multiple linear regression analyses were performed to determine associations between BMD and demographic and disease-related variables.

One hundred and sixty-three women were included. Median age was 47 (20-82) yrs, 89 (55%) were post-menopausal and 85 (52%) were taking glucocorticosteroids. BMD was significantly reduced in all measured sites compared with expected BMD. Thirty-seven (23%), 18 (11%) and 6 (4%) of the patients were osteoporotic in at least one, two and three or more measured locations. Bisphosphonates were used by 23 (27%) of patients taking glucocorticosteroids and 13 (35%) with osteoporosis. High age and low weight or BMI were associated with low BMD in all measured sites. In total hip, high SLICC/American Collage of Rheumatology (ACR), ESR and 'combinations of DMARD' were additional markers of low BMD. High S-creatinine was associated with low BMD in lumbal spine whereas high S-creatinine and CRP were markers in radius.

Women with SLE are at greater risk of osteoporosis compared with controls and few are treated adequately. Factors associated with low BMD in SLE are high age and low weight but also markers of inflammation, impaired kidney function and disease damage, however glucocorticosteroids were not associated.