19 November, 2012:
A total of 2341 postmenopausal women were recruited in five centers in Italy during 2006 and 2007 for quantitative ultrasound (QUS) measurement at the phalanges during a screening program for osteoporosis . Two ultrasound parameters were collected: amplitude-dependent speed of sound (AD-SoS) and ultrasound bone profile index (UBPI). Women were then re-contacted in 2010 (n = 2211) and were asked about fracture occurrence during the period since previous QUS measurement. The mean age of the recruited women was 60.9 ± 10.0 years, the mean age at menopause was 49.3 ± 4.4 years, and the mean body mass index (BMI) was 26.5 ± 4.6 kg/m2. A total number of 108 new major osteoporotic fractures occurred during the 3-year period, of which 23 were hip fractures and 51 were vertebral fractures. The relative risk (RR) per standard deviation (SD) decrease for major fractures was 1.77 (95% confidence interval (CI) 1.59–1.97) for AD-SoS and 2.06 (95% CI 1.78–2.37) for UBPI. When corrected for age, BMI, and age at menopause, the RRs were still significant and equal to 1.44 (95% CI 1.26–1.65) for AD-SoS and 1.67 (95% CI 1.39–2.00) for UBPI. The RR for vertebral fractures was 1.63 (95% CI 1.41–1.88) for AD-SoS and 1.73 (95% CI 1.44–2.08) for UBPI. The RR for hip fractures was 1.92 (95% CI 1.55–2.37) for AD-SoS and 2.68 (95% CI 1.86–3.86) for UBPI. Thus, this study showed that ultrasound parameters AD-SoS and UBPI were able to significantly predict future major fractures in a prospective cohort of more than 2000 postmenopausal women.
Quantitative ultrasound of the bone provides information not only about bone density but also on architecture and elasticity. It is a radiation-free technique, relatively inexpensive and easily transportable. Measurements at the fingers take only a few minutes. Theoretically, it seems to be the ideal modality for assessing bone strength, yet dual-energy X-ray absorptiometry (DXA), a much more expensive and time-consuming examination, is the gold standard recommended by health authorities and guidelines and is an important component of the FRAX risk assessment tool [2,3]. There could be several reasons for the existing inferiority of QUS versus the traditional DXA measurement. QUS examinations could be performed in several sites, which raises the question whether measurements at various peripheral sites (heel, finger, wrist) are similar in regard to their predictive values for vertebral and hip fractures. Other arguments relate to the accuracy of QUS when tested head-to-head with DXA, and to the efficacy of QUS, both as a screening tool and for monitoring the consequences of treatment, as compared to DXA.