Bad to the bone: The risk of osteoporosis

Estrogen plays an important undercover role in bone health, and in her first year after menopause, or after hormone therapy, a woman can lose several percentage points of bone mass. It happens without notice. That's why osteoporosis is sometimes called the silent disease. It doesn't hurt and it doesn't cause much trouble -- at first. But it can eventually wreak havoc in people's lives.

Osteoporosis is believed to be responsible for more than 1.5 million fractures each year, and many of those, especially hip and spine fractures, cause a lifetime of disability and can even hasten death.

One in two women and one in four men older than 50 will have an osteoporosis-related fracture at some point, according to the National Osteoporosis Foundation.

Although patients with osteoporosis can vary from a 45-year-old man who uses glucocorticoid to control his asthma, to a child with birth defects or a petite, 60-year-old grandmother, they will most commonly be older women. Eighty percent of those affected by the disease are women.

The prime time for bone health to begin its decline are the months and years surrounding menopause, and it is at this stage that a woman's bone health should receive attention, many physicians argue.

But what that attention should be -- beyond the traditional advice to consume sufficient calcium and get enough weight-bearing exercise -- is still a matter of some debate. And the discussion is further complicated by recent scientific evidence.

In 2002, the Women's Health Initiative offered findings that long-term use of estrogen and progestin resulted in an increased risk of breast cancer. This conclusion caused many women and their physicians to turn away from hormone therapy. That was bad news for bone health.

"Ironically, the first study to prove unequivocally that estrogen reduces fracture risk is the Women's Health Initiative, the very study that killed the drug," said Ethel Siris, MD, professor of clinical medicine at Columbia University College of Physicians and Surgeons, New York and director of the Toni Stabile Osteoporosis Center at New York Presbyterian Hospital.

In yet another irony, although the WHI proved the effectiveness of estrogen at reducing fractures, most women were probably not taking estrogen to improve the health of their bones in the first place, said Dr. Siris.

"They may well have been informed that one of the bonuses they were getting was bone protection, but they were probably taking [hormones] for symptom control or because of a conviction that it was protecting their heart."

Regardless, the bottom line is, "We've lost one of the drugs for osteoporosis that is a good drug," she said. And women who previously were gaining benefits without specifically seeking them now could literally be at a loss.

The osteoporosis toolbox

Fortunately there are other drugs that have proven to be effective at stemming bone decline. Among them are the bisphosphonates; the polypeptide hormone, calcitonin; parathyroid hormones; and selective estrogen receptor modulators.

And there are scanners to determine bone density. Many physicians consider dual-energy x-ray absorptiometry, or DXA scanners, to be the gold standard in determining bone health.

Dr. Siris would ideally like her patients to get a bone scan when stopping estrogen to find out how their bones compare to standards established by the World Health Organization. These values are used as a reference for the density levels of healthy 30-year-old women who are at their peak bone density.

Women who receive a score of minus 2.5, or 25% below the reference level, are determined to be in need of treatment.

National guidelines on bone density testing vary when it comes to recommending at what age women should first receive a scan. While all agree that women 65 and older should be tested, and Medicare covers the cost of a scan every two years, there isn't as much agreement about younger patients.

Felicia Cosman, MD, clinical director of the National Osteoporosis Foundation, would be likely to order a baseline bone scan for her patients younger than 65, as would Dr. Siris, even though the NOF guidelines suggest that younger patients should also have a risk factor to justify a scan.

"But I think ultimately we'll expand that recommendation," Dr. Cosman said. "There is no other way than bone density testing to really assess a person's risk."

Cost is a concern, she noted, "But as the cost comes down and more tests become available that are cheaper and we as a society realize that we can end up preventing a lot of disease by testing people, I think we'll expand that recommendation."

Some believe a bone density score should not be used as the sole trigger for beginning long-term pharmaceutical treatment.

And to treat or not to treat is a question that Robert Lindsay, MD, PhD, chief of internal medicine at Helen Hayes Hospital in West Haverstraw, N.Y., would like to see answered with an algorithm.

"DXA is a good tool, but it is only a tool for evaluating risk that is very similar to using only cholesterol to estimate the risk of heart disease. There are other risk factors involved, and the osteoporosis field is beginning to recognize that," said Dr. Lindsay.

A measure of bone density is a blind test, he said. "It is essentially taking some x-rays and passing them through the body and measuring what comes out the other end." Missing in this quick pass-through is a determination of other components of bone that make up the strength and stability of the skeleton -- factors that are being called bone quality.

"Bone quality would be anything that isn't measured by bone densitometry. It includes architecture of the skeleton, the material and composition of the skeleton and the rate of remodeling, or bone turnover," said Dr. Lindsay.

Determining fracture risk

To counter the fixation on bone density score as a number that may come to mean more than it should in determining bone health, experts in the field of bone health and osteoporosis are working on a formula for use by physicians to determine the absolute risk of a patient having a fracture.

The formula, which should be ready in a year or two, would be similar to one developed by cardiologists to determine an individual's risk of a heart attack within a given number of years. Such an algorithm will likely include a bone density score, the rate of bone turnover and a list of other risk factors such as age, gender, body weight, history of cigarette smoking, past history of a fracture and family history of osteoporosis.

"These are being melded in the same sort of constellation that the cardiologist uses so the primary care physician can say to Mrs. Smith, 'I've looked at all your risk factors and you've got a 5%, 10% or 20% risk of breaking a bone in the next five years.' "

The figure then becomes much more meaningful to the physicians and to the patient, and a discussion can take place as to whether the level of risk is acceptable or not, he said.

"Today there is almost a knee-jerk response to using a bone density number in an attempt to treat," he said. "That means that at any given level of bone density you are treating quite a lot of people who may never fracture in order to treat the one person who is going to fracture from fracturing in the future. This is not a very efficient way of using medicine."

Laura Tosi, MD, chair of the dept. of orthopedic surgery at Children's National Medical Center in Washington, D.C., would agree. She comes at the issue of broken bones from the perspective of someone who fixes them -- a lot. However, she places little value in the development of an algorithm or even in bone density screening in general.

"If I thought you could get the internists to sit down with people and fill out forms and calculate risk and that this would get people to change their behavior, I would be all for it," she said. "But I think there is an overwhelming amount of data that shows they aren't going to change their behavior.

"There isn't even data that demonstrate that DXA screening has reduced fracture rates in any way," she added.

Patient history plays role

Dr. Tosi advises that patients who have already had a fracture, particularly a low-energy or fragility fracture that occurred from a standing height or less, should be the ones most closely scrutinized for risk of future fractures. Such fractures, which often occur in the wrists of younger women, should alert a physician that the patient is at high risk of subsequent fractures that may be of the hip or vertebrae which could result in more serious consequences.

"You have to start somewhere when you are trying to change public behavior," she said, and the population with broken bones that comes to orthopedic surgeons' offices is a great place to start. "These people have a compelling interest to do something. They hurt."

But such patients may be slipping through the cracks. A study of nearly 4,000 women 50 and older that was published in the December 2003 issue of the Journal of Bone and Joint Surgery revealed there is a substantial gap between guideline recommendations and actual follow-up of patients using bone density measures and pharmaceutical treatments.

"Every patient who has had a low-energy fracture should consider, 'I broke a bone. Maybe I have weak bones. I need to discuss this possibility with my physician,' " said study author Adrianne C. Feldstein, MD, assistant medical liaison for research at the Kaiser Permanente Center for Health Research in Portland, Ore.

The American Academy of Orthopaedic Surgeons recently published recommendations that were endorsed by several international bone health groups as well as the National Osteoporosis Foundation. The recommendations stress that optimal care of fragility fracture patients includes not only the management of the presenting fracture, but also evaluation, diagnosis and treatment of the underlying cause or causes of the fracture, including low bone density or other medical conditions.

The question of how many patients to have scanned and treated may depend on a physician's specialty and which guidelines the physician follows. But there is hope on the horizon for more comprehensive recommendations in the form of a surgeon general's report on osteoporosis that is due out this year.

There was a clear need for such a report, said Allan S. Noonan, MD, MPH, senior adviser in the Office of the Surgeon General. "Osteoporosis is underdiagnosed and undertreated," he told a group gathered at the National Institutes of Health in December 2003 for the seminar "Boning Up on Osteoporosis."

"I hope the report will awaken health care providers and help them understand what they should be doing," he said.