Surgically induced weight loss produces as much as a 40% reduction in deaths in the 10 years after the operation, two large studies reported today.
Researchers already knew that bariatric surgery sharply reduced diabetes, hypertension and high cholesterol, in addition to improving appearance and quality of life. But the new studies, reported in the New England Journal of Medicine, are the first to document a long-suspected link between weight loss and survival.
"It is now absolutely clear that losing weight and keeping the weight off adds years to your life," said Dr. Edward H. Phillips, a bariatric surgeon at Cedars-Sinai Medical Center, who was not involved in the studies.
"The message is that if you are a morbidly obese diabetic, you are going to get sick and you are going to die young," said Dr. George A. Fielding, a bariatric surgeon at New York University, who also was not involved in the studies. "Here is an opportunity to take control of that situation."
Last year, about 177,600 Americans had bariatric surgery, according to the American Society for Metabolic and Bariatric Surgery. But that is less than 1% of those eligible for the surgery under the current criteria, the society said.
Guidelines call for a prospective patient to have a body mass index, or BMI, of 40, or a BMI of 35 and at least one other condition, such as diabetes or hypertension. For a 5-foot-10-inch person, a weight of 245 pounds would translate to a BMI of 35, and a weight of 275 pounds to a BMI of 40.
"If you have a BMI of 33 and have hypertension and diabetes, that is not much different from having a BMI of 40, and there is a real benefit to be had from getting the weight off," Fielding said.
In light of the studies and other results that have been accumulating over the last decade, those criteria should be eased to make more people eligible for the surgery, Dr. George A. Bray of Louisiana State University said in an editorial accompanying the studies.
The National Institutes of Health will convene a panel this fall to consider whether the guidelines should be changed.
There are two main types of bariatric surgery. The simplest is banding, in which an inflatable silicone band is placed around the stomach to reduce its capacity, allowing the patient to feel full after consuming much less.
In a gastric bypass, the stomach is sewn shut to reduce its capacity to three or four ounces, and the intestines are connected directly to the newly created pouch, bypassing part of the area where food absorption occurs. This is generally a more invasive surgery, but it produces greater weight loss.
In the first study, Dr. Lars Sjostrom of Gothenburg University in Sweden studied 2,010 obese patients who underwent bariatric surgery and 2,037 patients who received conventional medical treatment for their obesity. One-third underwent gastric bypass, while the rest had a form of banding.
After 10 years, the patients who had a bypass had lost 25% of their weight, and those who underwent banding had lost about 15%. Those receiving conventional medical treatment did not lose or gain more than 2% of their starting weight.
There were 129 deaths in the control group over the 10-year period and 101 in the surgery group. Taking into account age, sex and risk factors, that amounted to a 29% reduction in the number of deaths, researchers said.
The study was supported by several pharmaceutical companies and the Swedish Medical Research Council.
In the second study, Dr. Ted D. Adams of the University of Utah School of Medicine and his colleagues compared 7,925 obese patients who underwent gastric bypass surgery with an equal number of patients who did not. The study did not examine weight loss.
During the average seven years of follow-up, Adams and his colleagues found that the surgery patients had a 56% decrease in deaths from cardiovascular disease, a 92% drop in deaths from diabetes and a 60% decline in deaths from cancer.
Those declines were partly offset by an increase in deaths from suicide, accidents and poisoning, but overall the number of deaths dropped by 40% in the surgery group, when adjusted for risks and other factors -- 213 deaths in the surgery group and 321 in the control group.
Adams attributed the increased deaths from suicides to the fact that some severely obese people suffered from mood disorders or post-traumatic stress disorders, and they might be more likely to seek surgery to improve their body image. The increased number of accidents may indicate that those who lost weight were taking part in more normal activities.
The study was funded by the National Institutes of Health, the Utah Department of Health and the University of Utah.
"The interesting thing about gastric bypass," Phillips said, "is that there appear to be effects of the surgery other than weight loss. It changes gut hormones, changes how lipids are handled by the body, and there may be other things we don't even know about." He noted, for example, that the symptoms of diabetes declined sharply well before significant weight loss occurred.