Predictors of bone mineral density and osteoporosis in patients attending a rheumatology outpatient clinic

The aim of this study was to evaluate determinants of bone mineral density (BMD) and osteoporosis in patients attending our rheurnatology outpatient clinic. A cross-sectional analysis of 320 patients with rheumatism (248 noninflammatory and 72 inflammatory arthropathies) was done. Bone mineral density was measured in the lumbar spine (posteroanterior and lateral views) using dual-energy X-ray absorptiometry. Single and multiple analyses were used to assess associations between BMD and potential risk factors including age, height, weight, body mass index (BMI), alkaline phosphatase (ALP), calcium (Ca), phosphorous (P), magnesium (Mg), spot urine calcium/creatinine (Ca/Cr) ratio, erythrocyte sedimentation rate (ESR), G reactive protein (CRP), total cumulative dose and mean daily dosage of prednisolone, and duration of therapy. In these patients, there were significant correlations between BMD and age (r=-0.372, P=0.000), height (r=0.308, P=0.000), weight (r=0.145, P=0.011), and ALP (r=-0.262, P=0.000). By multiple regression analysis, age and ALP were found to be significant predictors of BMD (r(2) =0.253, P<0.01). Two hundred eighty-three of the patients had osteoporosis. Multiple logistic regression analysis showed that age and ALP were significant determinants for osteoporosis. These observations suggest that age and ALP were the major determinants of BMD and osteoporosis in these patients, suggesting a contribution of increased bone metabolism to loss of bone in cases of rheumatism.