Follow-up bone scans offer little aid, study says
Measuring density is still seen as a key predictor of fractures
Bone mineral density scans have become the gold standard to help doctors predict fractures for older women.
But repeating the tests up to eight years later has little benefit, according to a new study.
Dr. Teresa A. Hillier, Kaiser Center for Health endocrinologist and senior investigator based in Honolulu and Portland, Ore., and colleagues measured bone mineral density in 4,124 women between 1989 and 1990 and again about eight years later.
The women averaged 72 years of age, were mostly Caucasian and had never had a fracture, Hillier said.
Asian women also are at high risk for osteoporosis, she said, but no Hawaii women were in the study.
Participants in the Study of Osteoporotic Fractures were recruited from communities in Portland, Minneapolis, Pittsburgh and Baltimore, she said.
The Bone Mineral Density Scan is commonly used for osteoporosis screening for women age 65 and older and is often repeated to evaluate fracture risk, she said. The purpose of the study was to determine the value of a repeat test.
The team measured the BMD in the study group, determined the rate of change up to eight years later and followed the women for five more years to see which women developed fractures.
"We set out expecting to quantify the benefits of a repeat test," Hillier said, "but what we found was, even though there was an average BMD loss over time, the second test ... had no additional value from the first test.
"It was no better than chance alone" in predicting actual fractures observed in the study, she said.
In the follow-up period after the repeat test, 877 women had a nontraumatic fracture, including 275 hip fractures and 340 spine fractures, the researchers reported.
They said the women's initial BMD measurements were low on an average compared with young women but not in the range for osteoporosis. The group lost an average of .59 percent of bone mass per year between examinations.
"We did not find any improvement in the overall predictive value ... in a second measure of BMD, obtained a mean (average) of eight years later, in prediction of hip, spine or overall non-spine fracture risk," the researchers said.
"In other words, the initial BMD was highly, and similarly, predictive of fracture risk in our population."
A repeat Bone Mineral Density scan might be useful in some women, such as those with health factors that contribute to rapid bone loss and younger women in early menopause, the team reported.
"However, our results do suggest that, for the average healthy older woman 65 years or older, a repeat BMD measurement has little or no value in classifying risk for future fracture -- even for the average older woman who has osteoporosis by initial Bone Mineral Density measure or high BMD loss."
More research is needed on younger women, other ethnic groups and men to confirm their results, the researchers said.
The study was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases and National Institute of Aging, and published in last Monday's issue of Archives of Internal Medicine, Journal of American Medical Association.