Can radial bone mineral density and quantitative ultrasound measurements reduce the number of women who need axial density skeletal assessment?

The purpose of this study was to investigate the clinical usefulness of forearm bone mineral density (BMD) and speed of sound (SOS) at the phalanx and radius as pre-selection tests to identify women with low BMD at the axial skeleton. BMD was measured by dual-energy X-ray absorptiometry (DXA) in the forearm, lumbar spine and femoral neck. SOS at the radius and phalanx was measured using a multisite quantitative ultrasound (QUS) device. Measurements were performed on 524 consecutive women referred for the assessment of BMD. Women with a T-score < -1 and T-score <= -2.5 at either spine or femoral neck were identified, and T-score cut-off values for the forearm DXA and QUS variables were determined. Cut-off values for the forearm BMD estimated to detect normal women and those with T-score < -1 at the axial skeleton identified a total of 82% of subjects with 91% certainty. Cut-off values for the forearm BMD determined to detect women with T-score >-2.5 and those with osteoporosis allowed the identification of 62% of the study population with 90% certainty. Cutoff values for the phalangeal and radial SOS estimated to detect normal women and those with T-score < -1 at the axial skeleton identified a total of 49% and 1% of subjects, respectively. Cut-off values estimated for QUS variables to detect women with T-score >-2.5 and those with osteoporosis at the axial skeleton either failed to detect subjects with sufficient certainty (phalangeal SOS) or detected a negligible percentage of patients (radial SOS). In conclusion, forearm BMD may be used as a pre-selection test to identify women with low BMD at the axial skeleton, thus enabling reduction of the number of women who need axial BMD assessment. SOS of the phalanges and radius appears to have less value in the detection of the women with low axial BMD.