Comparison of the Achilles Express ultrasonometer with central dual-energy X-ray absorptiometry

BACKGROUND: Quantitative ultrasound (QUS) devices provide portable, easy-to-operate, low-cost options for point-of-care screening of bone mineral density (BMD). Community pharmacists should be aware of the precision, sensitivity, and specificity of these devices prior to their purchase. OBJECTIVE: To determine the precision, sensitivity, and specificity of the Achilles Express ultrasonometer compared with central dual-energy X-ray absorptiometry (cDXA) as well as its utility as a bone density screening device in the community pharmacy setting. METHODS: A prospective study in a community pharmacy and outpatient ambulatory clinic was conducted with 2 groups of white women. Group 1 participants were 25-35 years of age (young, healthy), and those in Group 2 were 45 years of age or older (postmenopausal). BMD assessments of the spine and the nondominant wrist and hip were performed using cDXA. Assessments of the heel were performed using the Achilles Express, a QUS device. The main outcome measures were correlation of t-scores between cDXA and QUS measurements using the Pearson correlation test. RESULTS: Twenty-two (30 +/- 4 years of age) and 31 (55 +/- 17 years of age) women were enrolled into Groups 1 and 2, respectively. Significant correlations between QUS and hip and spine cDXA t-scores were found in both groups. Correlation coefficients for QUS versus hip cDXA were 0.51 (95% CI 0.11 to 0.77) and 0.70 (95% CI 0.46 to 0.85) in Groups 1 and 2, respectively. Correlation coefficients for the QUS versus spine cDXA were 0.64 (95% CI 0.31 to 0.84) and 0.60 (95% CI 0.31 to 0.79) in Groups 1 and 2, respectively. The QUS device has a sensitivity level of 88% and specificity of 71% to detect a hip cDXA t-score of less than-1. CONCLUSIONS: The Achilles Express ultrasonometer is a reasonable screening tool to detect low BMD in postmenopausal women.