Twenty-five studies (n=6,676) were included in the review. The studies evaluated a number of parameters: broadband ultrasound attenuation (11 studies, n=2,519), speed of sound (4 studies, n=989), velocity of sound (4 studies, n=770), quantitative ultrasound index (11 studies, n=3,054) and stiffness parameter (4 studies, n=1,729).
Study quality (for studies that evaluated the quantitative ultrasound index parameter).
All of the included studies enrolled participants prospectively and 3 studies selected patients either consecutively or by random sampling. All studies had 30 or more participants with and without DXA-defined osteoporosis, and had completion rates greater than 90%. Most studies did not report the time elapsed between ultrasound and DXA, and no study reported that the ultrasound and DXA results were assessed independently.
The AUC was 0.76 (95% CI: 0.72, 0.79) for the quantitative ultrasound index parameter (11 studies), 0.77 (95% CI: 0.73, 0.81) for broadband ultrasound attenuation (11 studies), 0.74 (95% CI: 0.71, 0.77) for speed of sound and velocity of sound (4 studies), and 0.79 (95% CI: 0.71, 0.86) for stiffness (4 studies).
Subgroup analyses for the quantitative ultrasound index parameter gave an AUC of 0.76 (95% CI: 0.70, 0.82) for studies of women only, and an AUC of 0.75 (95% CI: 0.66, 0.82) for studies of postmenopausal women only.
Pre- and post-test probabilities of DXA-defined osteoporosis were tabulated by age group (50 to 59 years, 60 to 69 years, 70 to 79 years, and 80 years or older), and for three ultrasound T-score thresholds. For example: at a pre-test probability of 22% (65-year-old white woman at average risk), the post-test probability was 34% (95% CI: 26, 41) after a positive test and 10% (95% CI: 5, 12) after a negative test, using a T-score threshold of -1.