Frax relies on a long list of variables that influence risk: age; sex; weight; height; previous fractures in patients and their parents; current smoking status; prior chronic treatment with glucocorticoids; a diagnosis of rheumatoid arthritis (not osteoarthritis); a diagnosis of secondary osteoporosis (bone loss from a trauma or illness); level of alcohol consumption (more than three daily glasses of wine, or the equivalent, increases the likelihood of a break); and low bone mineral density at the femoral neck (a frequent site of hip fracture, just below the bony knob of the upper thigh bone).
After patients fill out a simple online survey, the FRAX calculator weights the risk factors according to the most recent data and spits out two numbers—a 10-year probability of hip fracture and a 10-year probability of any major fracture of the hip, spine, forearm or shoulder. Those numbers are a rough guide, the WHO emphasizes, and should not substitute for a doctor's clinical judgment about a particular patient. Someone who smokes and binge drinks frequently and has already had a painful fractured hip, for example, is probably more likely to suffer another broken hip than a light smoker and drinker of the same age who has had a painless vertebral fracture that could barely be detected by x-ray. Even so, the FRAX calculator would give those two people the same score.
Despite FRAX's flaws, Cummings says the tool is an improvement in risk prediction because it puts bone density in proper context as “one factor—an important factor but just one factor—in your likelihood of fracture.” Bone health experts currently recommend a baseline bone scan and FRAX calculation around age 65. And anyone—male or female—older than their mid-50s who fractures any bone in the absence of a car accident or similar trauma should be evaluated for osteoporosis and considered for bone-building drugs. Too many emergency room doctors today, Seibel says, are still just setting the broken arm or wrist and sending the patient home. After late middle age, experience and statistics confirm, there is no such thing as a simple fracture.
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