Obesity (search) surgery, the most drastic way to lose weight, is far more than a cosmetic procedure and involves considerably higher risks of death than previously thought, new research suggests.

Some previous studies of people in their 30s to their 50s — the most common ages for obesity surgery — found death rates well under 1 percent. But among 35- to 44-year-olds in a new study, more than 5 percent of men and nearly 3 percent of women were dead within a year, and slightly higher rates were seen in patients 45 to 54.

Among patients 65 to 74, nearly 13 percent of men and about 6 percent of women died. In patients 75 and older, half of the men and 40 percent of the women died.

"The risk of death is much higher than has been reported," said University of Washington surgeon Dr. David Flum, lead author of the study of 16,155 Medicare patients. "It's a reality check for those patients who are considering these operations."

The study, involving patients who underwent obesity surgery between 1997 and 2002, appears in Wednesday's Journal of the American Medical Association (search).

The study offered no breakdown on causes of death, but obesity surgery's potentially deadly complications can include malnutrition, infection, and bowel and gallbladder problems. Also, surgery in general can be a deadly shock to the system, especially in older patients.

Dr. Neil Hutcher, president of the American Society for Bariatric Surgery (search), said that Medicare patients are probably sicker than the general U.S. population and that complication rates have declined as surgeons' expertise has increased.

But Flum said some previous research on the safety of obesity surgery consisted of "reports from the best surgeons reporting their best results," while the new study is more of a real-world look.

The American Society for Bariatric Surgery predicts obesity surgery will be performed more than 150,000 times this year in the United States. That is more than 10 times the number in 1998, according to a second JAMA study. The increase parallels a surge in the portion of U.S. adults who are at least 100 pounds overweight, from about 1 in 200 in 1986 to 1 in 50 in 2000, that study said.

Supporters of stomach-reduction surgery say the operation can save their lives by reducing the workload on the heart and lungs and eliminating related illnesses, such as diabetes and sleep apnea.

Flum said the new study suggests that in many cases, obesity surgery may not be right for an older person "who already has the burden of 60 years of obesity on their heart" and other organs.

Medicare covers obesity surgery if it is recommended to treat related conditions such as diabetes and heart problems. The government is considering whether to cover surgery to treat obesity alone.

Medicare is for younger Americans with disabilities and for patients 65 and older. Flum said most of the patients he studied were under 65 and probably qualified for Medicare because of obesity-related ills, including heart and joint problems.

There are several types of obesity surgery, but the most common U.S. variety, gastric bypass, involves creating an egg-size pouch in the upper stomach and attaching it to a section of intestine. That reduces the amount of food patients can eat and results in less food being absorbed. Flum's study lumped together data on the different operations.

Researchers said one reason men may have higher post-surgery death rates is that they tend to wait longer than women to seek medical help and may be sicker when the operation is performed.

A third JAMA study cast doubt on whether obesity surgery reduces health-care costs. It found that among patients followed for about three years, an average of 8 percent were hospitalized before surgery, mostly for obesity-related complications, compared with 20 percent a year afterward, mostly for surgery-related complications.

That study's lead author, Dr. David Zingmond of the University of California at Los Angeles, said some people mistakenly view obesity surgery as a cosmetic procedure and "may greatly discount the chances that they're going to have problems after surgery."

Hutcher said patients should seek experienced surgeons who meet his group's guidelines. Those include thoroughly evaluating patients before and after surgery and giving them long-term follow-up care.

Most patients "will receive a good outcome. A good outcome does not mean there's no risk for complications or mortality," Hutcher said.