Does the combination of quantitative ultrasound and dual-energy X-ray absorptiometry improve fracture discrimination?

The widespread availability of quantitative ultrasound (QUS) and X-ray abso rptiometry densitometers raises the question of whether a combination of QU S and bone mineral density (BMD) measurements could provide a clinically us eful method of enhancing the prediction of fracture risk. The aim of this s tudy was to examine whether a combination of axial BMD and calcaneal QUS me asurements can enhance fracture discrimination compared with either method alone. The study population consisted of 154 postmenopausal women with a hi story of atraumatic fracture at the spine, hip or forearm and 221 healthy p ostmenopausal women with no clinical risk factors for osteoporosis. Subject s had dual-energy X-ray absorptiometry (DXA) measurements of the lumbar spi ne (LS), femoral neck (FN) and total hip (THIP) and calcaneal broadband ult rasound attenuation (BUA) and speed of sound (SOS) measurements on the Holo gic Sahara (SAH) and Osteometer DTUone (DTU). Z-scores were calculated usin g the mean and SD obtained from the healthy postmenopausal group. Logistic regression analysis yielded odds ratios for BMD measurements at the LS, FN and THIP of 2.2, 2.2 and 2.3, respectively. The odds ratios obtained for QU S measurements ranged from 2.5 for DTU BUA to 3.3 for SAH SOS. While these odds ratios for QUS measurements were higher than those obtained for BMD me asurements, the differences were not statistically significant. When the od ds ratios for QUS were adjusted for BMD at the spine and hip, the odds rati os remained significant in all cases indicating that QUS and BMD variables contribute independently to fracture discrimination. When the BMD-adjusted odds ratios were compared with those for QUS alone, they were slightly lowe r but not significantly so. When the QUS measurements were adjusted for THI P BMD, the odds ratios for QUS tended to be lower than when adjusted for LS and FN BMD. The Z-scores for each of the QUS measurement variables were co mbined with spine or hip Z-scores. Logistic regression analysis of the QUS and BMD combined Z-scores yielded slightly higher odds ratios of approximat ely 3.1 (compared with 2.9 obtained for QUS alone) and increases in the are a under the curve of approximately 2%. However, these increases were not cl inically significant. In conclusion, the combination of axial BMD and calca neal QUS measurements did not significantly improve fracture discrimination compared with either method alone.