Health Research

February 15, 2007

Are Repeat Bone Tests Unnecessary?

Kaiser Permanente research shows repeat bone mineral density scans don't help predict fractures for most older women

Repeating a bone mineral density scan (BMD) up to eight years after an initial scan provides almost no additional value in predicting fractures among older postmenopausal women. This conclusion from the Study of Osteoporotic Fractures appeared in the January 22 issue of Archives of Internal Medicine.

"Our analysis showed that an initial BMD scan was highly predictive of fracture risk in older women," says Teresa A. Hillier, MD, MS, lead author and a senior investigator at The Center for Health Research. "It also showed that a repeat BMD scan eight years later did not increase predictive value. Given the cost of these scans - $125 to $350 - it appears that, given the choice, scarce health care dollars would be better spent on other screening tests or preventive interventions rather than on repeat BMD tests in healthy older women."

BMD as measured by a method known as dual-energy X-ray absortiometry helps physicians predict fractures and has become the gold standard for osteoporosis screening. Current guidelines recommend screening all women at age 65 for osteoporosis, using BMD measurements. There is scant scientific evidence supporting repeat BMD testing for predicting fracture risk, but repeat scans are commonly performed in clinical practice, often at two-year intervals.

Hillier and colleagues measured total hip BMD in 4,124 older women participating in the study (with the average age of 72 years) between 1989 and 1990 and again an average of eight years later. They calculated the rate of change in BMD and followed the women for an average of five years after the repeat BMD to see which women developed fractures.

During the follow-up period, 877 women had a non-traumatic, non-spine fracture (including 275 hip fractures), and 340 women incurred a spine fracture. On average, the women's initial BMD measurements were low compared to young women but not in the osteoporotic range. The group lost an average of .59 percent of their bone mass per year between exams.

"A second BMD scan did not improve predictive values for hip, spine or overall non-spine fracture risk," Dr. Hillier says. "Despite this finding, repeat BMD scans might still be useful in some women, including those with clinical factors that contribute to very rapid bone loss and younger women in early menopause. But for the average healthy older woman, a repeat BMD scan has little or no value in predicting risk for future fracture–even for the average woman who has osteoporosis at the initial BMD scan or has high BMD loss."