A prediction rule obtained by using quantitative ultrasonographic (US) stiffness index and four clinical risk factors helped discriminate, with high sensitivity, women at higher versus those at lower risk for osteoporotic fracture, according to a study in the July issue of Radiology.
Idris Guessous, MD, from the department of internal medicine at Lausanne University Hospital in Lausanne, Switzerland and colleagues said that a prediction rule was computed by using data from a three-year, prospective multi-center study to assess the predictive value of heel-bone quantitative US in 6,174 Swiss women aged 70–85 years.
The researchers used quantitative US device to calculate the stiffness index at the heel. Baseline characteristics, known risk factors for osteoporosis and fall, and the quantitative US stiffness index were used to elaborate a predictive rule for osteoporotic fracture.
The investigators said they determined the predictive values by using a univariate Cox model and adjusted them with multivariate analysis.
Guessous and colleagues found that there were five risk factors for the incidence of osteoporotic fracture: older age ( >75 years), low heel quantitative US stiffness index ( <78 percent), history of fracture, recent fall and a failed chair test.
The authors wrote that score points assigned to the risk factors were as follows: age, 2 (3 if age > 80 years); low quantitative US stiffness index, 5 (7.5 if stiffness index < 60 percent); history of fracture, 1; recent fall, 1.5; and failed chair test, 1.
The cutoff value to obtain a high sensitivity (90 percent) was 4.5, according to the authors. With the cutoff, the researchers found that 1,464 women were at lower risk (score, <4.5) and 4,710 were at higher risk (score, ≥ 4.5) for fracture.
Among the higher-risk women, Guessous and colleagues found that 6.1 percent had an osteoporotic fracture, versus 1.8 percent of women at lower risk. Among the women who had a hip fracture, 90 percent were in the higher-risk group.
Based on their results, approximately 6 percent of those with poor ultrasound scores broke a bone compared to less than 2 percent of the others.
The researchers recommended that all women age 65 or over are recommended to get a bone density test.
“As you can imagine, the eligible population is really large,” the authors wrote. They concluded that ultrasound might present a cost-effective way to offer initial scans to large populations of outwardly healthy people.