Bone health: study on people at fracture risk

For the millions of Americans with bones that are thinning as they age, this question arises: Who should be treated with bone-enhancing drugs?  The drugs currently available to enhance bone density are far from perfect. They are expensive, they can have side effects, and they are only about 50 percent effective at preventing fractures.

Until recently, many doctors and drug companies that make these medications were saying almost everyone — especially older white women, who are at highest risk of one day suffering an osteoporotic fracture.

These low-trauma fractures are debilitating and costly, adding more than $17 billion a year to the national health care bill. Among elderly people who fracture a hip, 10 percent to 20 percent die within six months; many more spend the rest of their lives in nursing homes or needing full-time home care.

The National Osteoporosis Foundation reports that “about one out of every two Caucasian women will experience an osteoporosis-related fracture at some point in her lifetime, as will approximately one in five men.”

“Although osteoporosis is less frequent in African-Americans,” the foundation continues, “those with osteoporosis have the same elevated fracture risk as Caucasians.”

Before any treatment, possible risks should be weighed against known benefits.

If you have osteoporosis, defined as a T score — the standard measure of bone density — of minus 2.5 or lower, or you have already had an osteoporotic fracture of the forearm, hip, shoulder or spine, the answer is clear: treat. For you, experts say, the benefits of treatment are expected to far outweigh the risks.

But what about the much greater number of women and men whose bones are not as strong as they were at age 30 but who have not yet become osteoporotic — with T scores in the hip or spine of minus 1 to minus 2.5? They are said to have osteopenia, which may or may not eventually lead to osteoporosis. Who among them would most likely benefit from treatment?

A Tool to Help

To help answer this question, the World Health Organization has devised a controversial tool called FRAX, an online risk calculator to help doctors and patients analyze the likelihood of future osteoporotic fractures and determine whether drug therapy might prevent them.

The controversy stems largely from the fact that not every possible contributor to fracture risk has been factored into the FRAX formula. In its latest “Clinician’s Guide to Prevention and Treatment of Osteoporosis,” the National Osteoporosis Foundation provides a full list of the lifestyle factors, conditions, diseases and medications that contribute to the risk of osteoporosis and fractures.

Especially missing from FRAX are weight-bearing exercise, which has a certain benefit, and a diet that builds bone, which is itself subject to some debate. But the W.H.O. formula includes most of the major players, called clinical risk factors, that affect bone health. And if FRAX is used properly, it can result in far wiser treatment decisions than might otherwise be made.

The formula provides a means of estimating someone’s probability of suffering a hip fracture or major osteoporotic fracture within 10 years, providing numbers that doctors and patients can understand. The risk factors it considers are age, gender, weight and height, a previous fracture, a parent with a hip fracture, current smoking, treatment with corticosteroids, alcohol consumption, rheumatoid arthritis and secondary osteoporosis due to a deficiency of vitamin D or excess of parathyroid hormone.

The formula can be applied to men and women across categories of race and ethnicity. In addition, it can be used without knowing a person’s bone density score, although having this test result can enhance the accuracy of the prediction.

“If, using FRAX, someone’s fracture risk is really low, a bone mineral density test probably wouldn’t change the risk very much,” Dr. Susan M. Ott, a bone specialist affiliated with the University of Washington in Seattle, said in an interview. “And if the risk using FRAX is really high, you don’t need the test; you need treatment.

“But if your FRAX risk is in between, getting a bone mineral density test can help you decide whether you need treatment.”

In the journal Osteoporosis International, Dr. Ethel Siris of NewYork-Presbyterian Hospital/Columbia University Medical Center notes that although people with osteopenia have a low fracture risk, many more fall into this midrange of bone density and “total fractures exceed those occurring in persons with osteoporosis.” Dr. Siris says FRAX helps identify “those in the low bone mineral density range who have the highest risk of fracture.”

Sample Calculations

In Clinical Correlations, an internal medicine blog of New York University, Dr. Judith Brenner demonstrated the power of the FRAX tool. Dr. Brenner calculated the risk for a 60-year-old white woman who is 5 feet and 110 pounds, with no family or personal history of fracture and no history of smoking or using steroids. Using FRAX, the risk of a hip fracture within 10 years for this woman is 1.5 percent.

If the same woman instead weighed 200 pounds, her risk would drop to 0.5 percent (more on the reasons below). But if the 110-pound woman had a parent who suffered a hip fracture, her risk would rise to 1.9 percent. Add smoking, and the risk goes to about 2.9 percent. Add steroids, and the risk rises to 5.9 percent. Add daily consumption of two or more alcoholic drinks, and the risk becomes 9 percent.

Instead of 60, say the woman is 80, slender and with no family or personal history of fractures, smoking or steroid use. Dr. Brenner calculated her risk of fracturing a hip in 10 years as 10 percent and of having any major osteoporotic fracture at 35 percent.

Considering the cost and effectiveness of established treatments, Dr. Brenner wrote, in deciding to treat, “the magic number is a 3 percent risk of hip fracture in 10 years or 20 percent risk of any other major osteoporotic fracture.”

When it comes to bone health, it pays to be heavier. Dr. Ott says that model-thin women are at significantly greater risk of breaking a bone. Extra body weight places more stress on bones, which stimulates them to become stronger. Also, body fat produces estrogen, which helps foster bone strength, especially in postmenopausal women.

But even for slender people, regular weight-bearing exercise is an enormous benefit to bones. “Walk, hike, dance — anything that’s weight-bearing can help protect the hips and spine,” Dr. Ott said.

A bone-healthy diet for women over 50 would provide about 1,200 milligrams of calcium and 1,000 international units of vitamin D daily. For those who take omega-3 fatty acids, Dr. Ott recommended using flaxseed oil rather than fish oil; the latter contains unknown amounts of vitamin A, which in excess can be detrimental to bones.