I share an anxiety with several women friends in their 50s and 60s. We've all been told that because our bone mineral density is low — though not low enough to meet the definition of the brittle-bone disease osteoporosis — we need to take medication to reduce our chance of fractures.
This means primarily hormones or Fosamax, the top-selling osteoporosis drug, for which doctors wrote more than 20 million prescriptions last year, nearly $2 billion worth. Knowing the associated risks — heart disease, stroke and breast cancer for hormones; ulcers of the esophagus and stomach, and jaw decay for Fosamax — none of us is eager to follow our doctors' orders.
Last month a study in the New England Journal of Medicine reinforced our concerns. The study found a possible link between the use of Fosamax and atrial fibrillation, or irregular heartbeat — a finding also suggested in earlier research. "Doctors should think twice about whether there is really enough benefit to warrant the potential risk of treating women who do not have osteoporosis with Fosamax," said study author Steven R. Cummings, of the California Pacific Medical Research Institute in San Francisco.
I also suspect my friends and I are a lot less at risk than someone in my parents' generation. My mom and three of her pals have all fallen and had fractures; no one I know in my generation has done either.
My search of the scientific literature suggests we are right to be wary of over-medication.
Low bone density is only one of several well-established risk factors for bone fractures. Age and fracture history are just as important, according to Michael R. McClung, director of the Oregon Osteoporosis Center and a member of the council of scientific advisers for the International Osteoporosis Foundation. None of these factors alone is very good at predicting fracture risk. But some doctors don't appear to have gotten the message.
"Many younger women whose bone density is borderline low are getting treated, although their risk of fracture in the next five to 10 years is fairly low," said Nelson B. Watts, director of the University of Cincinnati Bone Health and Osteoporosis Center and chairman of the Food and Drug Administration's Advisory Committee for Endocrine and Metabolic Drugs. "And many patients who have had fractures are not being evaluated or treated, even though their risk of a second fracture in the next five to 10 years is fairly high."
That could soon change. Later this year, World Health Organization scientists plan to finish sifting data from several international osteoporosis trials and publish a new fracture-risk tool. The tool will combine bone density with about 10 other risk factors to gauge an individual's risk. Several national organizations, including the National Osteoporosis Foundation (NOF), hope to revise their osteoporosis treatment guidelines accordingly to reflect a truer picture of fracture risk. The new guidelines will recommend treatment if your risk of breaking a bone in the next 10 years is above a certain level, perhaps 25 percent.
Ethel Siris, professor of clinical medicine at Columbia University Medical School, is among those calling for a new standard of treatment. Measuring bone density, via an X-ray called a DXA scan (dual-energy X-ray absorptiometry), she says, is a useful diagnostic tool. "But bone density measurements were never intended to serve as a guide for when to treat this person and not that one," explained Siris, who is also president of the NOF.
An estimated 10 million people in the United States have osteoporosis, putting them at risk for fractures that, according to the Centers for Disease Control and Prevention, can lead to long-term disability or even death.
My friends and I are part of an even larger group — about 34 million — with low bone mass, or osteopenia. It's a "pre-disease" category fraught with controversy: Many argue it should be treated, lest it lead to a worsening problem.
Cummings and Watts, on the other hand, challenge the view of osteopenia as a condition to be treated. "It describes half the women over 50," said Cummings, who says the two most commonly prescribed osteoporosis drugs, Fosamax and Actonel, have shown no benefit in osteopenic women; only hormones, he said, have proved effective for this group.
"The problem is that this category lumps together some people with very high risk and others at very low risk," McClung said. "We should not be treating them all the same."
To some extent, losing bone mass, or bone density, is a normal part of aging. For both men and women, density peaks during our 20s and 30s and then falls throughout our remaining lives. Bone tissue constantly renews itself, shedding old cells and forming new. But, at some point, bone formation begins to lag behind bone loss. For women, bone mass drops steeply after menopause; men lose mass more steadily. Because women begin with less bone mass and lose it at a faster rate, at any age women have lower bone densities than men.
So, what — besides bone mineral density — are the risk factors for fractures?
Age is one. The fracture rates for both men and women rise rapidly after age 75; the average age for hip fracture, for example, is 82. One 1998 study showed that women 85 or older have about 100 times the rate of hip fractures of women ages 45 to 54. Nonetheless, prevention efforts often miss the elderly because a marketing strategy for osteoporosis drugs is to target younger women like my friends and me, according to McClung. My mother is a case in point. She was not treated with Fosamax until age 88, after several falls and two broken bones.
A history of fracture also increases risk. Several studies have shown that a woman who has had a fracture is about twice as likely to experience another one as a woman of the same age and bone density without a previous fracture. "If you are a woman 50 or older and have had a spine or hip fracture, you . . . should be treated," Siris added.
But don't count on your doctor to recommend it: Three-quarters of people who fracture bones after age 45 are never evaluated for osteoporosis, Siris said. "The medical profession is still not caught up with the idea that we should be treating this population."
And then there's bone mineral density. A DXA scan shows how many grams of calcium and other bone minerals are packed into a segment of bone at the hip, spine or wrist — common fracture sites. The higher the mineral content, the denser the bone and the lower the fracture risk. Your T-score compares your reading to that of a 30-year-old (when bone mass peaks) of your sex. A score between zero and minus-1 is considered normal. Between minus-1 and minus-2.5 is defined as osteopenia. Anything lower than minus-2.5 is defined as osteoporosis; most medical societies recommend treating people in that category.
Other lifestyle factors that affect fracture risk include smoking, drinking (more than two drinks per day) and being skinny (weighing under 127 pounds or having a body mass index of less than 20). You're also at higher risk if your parents had a fracture, you use corticosteroids (including prednisone or hydrocortisone) or have rheumatoid arthritis.
Exercise, vitamin D and calcium also seem to influence risk. "There is good evidence in older adults that the combination of calcium and vitamin D, and probably vitamin D alone, reduces fall risk, bone loss and fracture incidence," McClung said. "While there is little evidence that weight-bearing exercise will effectively raise bone density in healthy adults, it seems to slow bone loss in older adults," he concluded. Weight-bearing exercises include walking, jogging, hiking, dancing, lifting weights and using elastic bands.
Finally, factors related to falling — such as poor
vision, frailty, reduced strength and mobility, poor balance and use of sedatives — are useful for predicting fracture risk in the elderly. Ninety percent of hip fractures are caused by a simple fall from standing height or lower.
One Step at a Time
Although my mother is clearly at high risk of fractures — two previous fractures, advanced age, poor vision, frail, poor balance — my research suggests that my osteopenic friends and I are on the low-risk end of the spectrum. Of all the risk factors, the only one that applies to me is parental history.
So I've struck a bargain with my gynecologist to stop taking low-dose hormones and try a regimen of vitamin D and weight-bearing exercises for a year to see if I can maintain my bone density.
I'll postpone riskier treatment options for when I reach a higher risk category.