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Formula Predicts Women's Fractures

Sept. 26, 2006 -- Australian researchers have come up with a mathematical formula to help predict bone fractures in women 60 and older.

The formula, described in Radiology's October edition, factors in bone mineral density at the hip and spine, history of fractures and falls, and weight.

Researchers included Margaret Joy Henry, BSc(Hons), PhD, at Australia's University of Melbourne.

Henry's team calls the formula the FRISK (fracture risk) score.

They created it by looking at 679 women age 60 and older. Participants included 231 women (average age: 74) who had had minor bone fractures in the two years prior to the study.

The other 448 women (average age: 72) hadn't had any bone fractures during that time.

Both groups included women with normal bone mineral density, osteopeniaosteopenia, and osteoporosisosteoporosis.

Osteopenia is bone mineral density that's lower than normal but not in the osteoporosis range. Osteoporosis is bone mineral density that's dangerously low, making fractures more likely.

Henry's team plugged the women's weight, bone mineral density at the hip and spine, history of falls, and previous fractures into their formula to get a FRISK score. Then the researchers tracked the women's fractures for the next five to six years.

During the first two years, the FRISK formula accurately predicted 75% of the women's fractures.

The odds of having a new fracture were higher for women with low bone-mineral density, past fractures, and a history of falls.

The findings about weight were a little more complex. Lighter women tend to have lower bone mineral density; heavier women often have higher density. And lighter women have been considered at greater risk for osteoporosis.

But after taking bone-mineral density into account, lighter women weren't at greater risk of fractures. That is, lighter women with strong bones weren't especially likely to have fractures.

In fact, adjusting for bone-mineral density showed that heavier women are at greater risk of fractures. Heavier weights apply more force to the skeleton during falls, the researchers note.

The formula's accuracy faded as the years passed, possibly due to factors not included in the formula, write Henry and colleagues.

The researchers are currently gauging fracture risk factors in men age 60 and older, according to a news release from the Radiological Society of North America, which publishes Radiology.