Identifying osteoporosis in a primary care setting with quantitative ultrasound: relationship to anthropometric and lifestyle factors

Abstract

Dual-energy X-ray absorptiometry (DXA), the "gold standard" for diagnosis of osteoporosis, is not recommended for population screening, and thus quantitative ultrasound (QUS) of the calcaneus is gaining popularity. The aim of the present study was to evaluate the relationship between QUS values and anthropometric and lifestyle factors, and to assess the diagnostic performance of QUS in predicting DXA-defined osteoporosis. Eight hundred and thirty-two women and 87 men aged 40-88 years were included in the study. Anthropometric measurements, the questionnaire, and QUS and DXA measurements were performed by trained physicians. Both QUS and DXA T-scores were lower for women than for men. Postmenopausal women had significantly lower QUS T-scores compared to premenopausal women (P < 0.001). Age over 50, female sex, sedentary lifestyle, fracture history, presence of chronic disease, and > or =5 years since menopause were associated with QUS T-scores lower than -1.00 by multivariate analysis. Low QUS T-scores were related to lack of direct sun exposure, high parity, fair skin color, and no education by univariate analysis (P < 0.005). A weak correlation was found between calcaneal QUS and DXA T-scores at lumbar spine (r = 0.310, P < 0.001) and femoral neck (r = 0.288, P < 0.001). The sensitivity and specificity of the QUS test were 73.7% and 57.4%, respectively, regarding the identification of osteoporotic patients. Lower QUS T-scores were associated with several osteoporotic risk factors, and the sensitivity and specificity of QUS for predicting DXA-defined osteoporosis were at optimum values at ages between 50 and 59 years. We conclude that, even though the accuracy of QUS for predicting DXA-defined osteoporosis is not remarkably high, it can be applied to identify subjects at risk in this age group in developing countries and rural districts who should be the focus of fracture prevention.