How does quantitative ultrasound compare to dual X-ray absorptiometry at various skeletal sites in relation to the WHO diagnosis categories?

The World Health Organisation (WHO) has proposed a set of guidelines for th e diagnosis of osteoporosis in adult women based on a measurement of bone m ineral density (BMD) expressed as the number of SD below young adult mean ( t-score). In this study, we investigated the number of subjects classified as either osteopenic or osteoporotic according to these guidelines using du al X-ray absorptiometry (DXA), at the hip, at the spine and at the lower fo rearm and quantitative ultrasound (QUS), at the heel. A total of 247 men, 2 09 postmenopausal women and 195 premenopausal women were included in the st udy. Furthermore, the study provides the first normative data showing the i nfluence of sex, age and menopause on broadband ultrasound attenuation (BUA ) and speed of sound (SOS), as measured by the DTU-one imaging ultrasound s canner. The difference between the number of patients classified into eithe r diagnosis group by the investigated parameters is large ranging from 25.9 % of the women being diagnosed as osteopenic by BUA at the heel to 43.0% by BMD at the femoral neck. For men, the same range is from 20.5% by BUA to 4 4.1% by BMD at the femoral neck. For the classification into the osteoporot ic group, the range is from 2.5% by intertrochanteric BMD to 24.4% by BMD a t Ward's triangle for women and from 0% by SOS to 29.0% by BMD at Ward's tr iangle for men. Using total hip BMD as the reference parameter to categoriz e the subjects as normal, osteopenic or osteoporotic, the agreement of the other parameters with this classification is assessed in terms of sensitivi ty and specificity. We conclude that there are significant differences in t he classification of osteoporosis/osteopenia depending on the site measured and the technique used for the bone mass assessment. Furthermore, we sugge st that development of technique and site specific cut-off values may incre ase the accuracy of the classification of osteoporosis/osteopenia in both m en and women.