Contact quantitative ultrasound: An evaluation of precision, fracture discrimination, age-related bone loss and applicability of the WHO criteria

The aim of this study was to assess a dry calcaneal quantitative ultrasound (QUS) device by examining: (i) short- and long-term precision; (ii) the ab ility of the ultrasound parameters to identify women with vertebral fractur es; (iii) age- and menopause-related bone loss; (iv) applicability of the W HO criteria in scan interpretation. The study group consisted of 422 health y women with no risk factors associated with osteoporosis (227 premenopausa l and 195 postmenopausal) and 93 women with one or more vertebral fractures . All women had calcaneal QUS and bone mineral density (BMD) measurements o f the lumbar spine and hip performed. Broadband ultrasound attenuation (BUA ) and speed of sound (SOS) measurements in the heel were combined and expre ssed as estimated heel BMD. Short-term precision studies yielded coefficien t of variations of 0.3% for SOS, 4% for BUA and 3.3% for estimated heel BMD . Standardized short-term precision values were approximately 0.2 SD. Long- term standardized precision errors ranged from 0.17 to 0.38 SD. All the QUS and BMD measurement parameters showed significant negative relationships w ith age in the postmenopausal group. Annual losses were 0.35 dB/MHz per yea r for BUA, 0.56 m/s per year for SOS and 0.002,g/cm(2) per year for estimat ed heel BMD. All the QUS and BMD parameters were able to discriminate betwe en healthy postmenopausal women and women with vertebral fracture. Age-adju sted odds ratios for each SD decline in QUS measurements were 3.63, 5.25 an d 4.79 for BUA, SOS and estimated heel BMD respectively. Corresponding odds ratios for BMD at the lumbar spine, femoral neck and total hip were 2.39, 2.51 and 2.95 respectively. When the QUS and BMD parameters were expressed as T-scores, estimated heel BMD showed the least age-related decline, while femoral neck BMD displayed the greatest decrease with age. The mean T-scor e and prevalence of osteoporosis (T < -2.5) for a Caucasian woman aged 60-6 5 years were -1.35 and 21% respectively for the lumbar spine compared with -0.59 and 2% for estimated heel BMD. In conclusion, this study revealed tha t contact ultrasound can detect age- and menopause-related influences on bo ne status and was able to discriminate between healthy individuals and wome n with vertebral fracture. However, the widely accepted threshold of a T-sc ore of less than -2.5 for the definition of osteoporosis may need modifying for the interpretation of QUS scans.