Date and Time
March 9, 2005
1:30 PM - 3:00 PM

Availability
Open to the public
No RSVP required

Speaker
Smita Nayak

Context: Dual-energy x-ray absorptiometry (DXA) is widely used for the diagnosis of osteoporosis; however, there is increased interest in the use of quantitative ultrasound technology for osteoporosis screening.

Purpose: To determine the sensitivity and specificity of calcaneal quantitative ultrasound for identifying patients who meet the World Health Organization (WHO) diagnostic criteria for osteoporosis, using DXA as the reference standard, and to determine posttest probabilities of DXA-determined osteoporosis from quantitative ultrasound results.

Data Sources: Researchers searched MEDLINE (1966-2004), EMBASE (1993-2004), Cochrane (1952-2004), and Science Citation Index (1945-2004) databases.

Study Selection: The researchers included English-language articles that evaluated the accuracy of calcaneal quantitative ultrasound for identifying adult patients with DXA T-scores of less than -2.5 at the hip or spine; had at

least 20 study participants; and presented sensitivity and specificity.

Data Extraction: Two authors independently reviewed articles and abstracted

data onto pre-tested abstraction forms.

Data Synthesis: The researchers determined summary estimates of sensitivity and

specificity at each quantitative ultrasound threshold and used these summary estimates in a weighted least squares regression to predict sensitivity and specificity as functions of threshold. They calculated post-test probabilities of DXA-determined osteoporosis for a variety of pre-test probabilities and thresholds. For example, if women aged 60-69 at average risk for osteoporosis were screened with quantitative ultrasound at a T-score threshold of -0.50, one would expect 29% of women with positive results and 7% of women with negative results to have DXA-diagnosed osteoporosis.

Conclusions: Although calcaneal quantitative ultrasound can rule out DXA-determined osteoporosis with reasonable certainty in populations with low pretest probabilities of DXA-determined osteoporosis, it has a high false positive rate. Calcaneal quantitative ultrasound is less useful for screening populations with high pretest probabilities of DXA-determined osteoporosis.