Performance of quantitative ultrasound in the discrimination of prevalent osteoporotic fractures in a bone metabolic unit.

There is a growing interest in ultrasound evaluation of bone status as an alternative to the measurement with dual X-ray absorptiometry (DXA), due to its low cost, portability, and nonionizing radiation. The aim of our study was to investigate the relation among DXA, QUS, clinical, anthropometric, and lifestyle factors, and to determine QUS cutoff values in order to discriminate fractures in patients referred to the Bone Metabolic Unit at an Endocrinology Service. We studied 300 patients (281 females and 19 males; age 58 +/- 11 years) referred for evaluation of osteoporosis. In all cases we determined basic anthropometric parameters, a clinical history including previous osteoporotic fractures and risk factors for osteoporosis, and QUS parameters in calcaneus (Hologic Sahara), and BMD in lumbar spine (LS) and femoral neck (FN), by DXA (Hologic QDR 1000). Using the WHO densitometric criteria, 37, 46.7, and 16.3% of our population were osteoporotic, osteopenic, and normal, respectively. A QUI T-score </=-1.5 SD provided a sensitivity of 68.9% and a specificity of 64.7% for osteoporotic fracture discrimination and a sensitivity of 64.9% and a specificity of 74.1% for osteoporosis defined by WHO criteria using DXA. In the logistic regression, the presence of family history of fragility fractures (OR: 3.03; CI 95%: 1.3-7.03), a DXA T-score </=-2.5 (OR: 3.58; CI 95%: 1.66-7.73), and a QUI T-score </=-1.5 (OR: 2.56; CI 95%: 1.15-5.69) were independently associated with prevalent osteoporotic fractures. In conclusion, calcaneus ultrasound appears as a useful technique for the routine clinical practice, as its performance is similar to DXA for the discrimination of subjects with osteoporotic fracture.