These findings differ from previous research, which has shown a modest improvement in survival rates. Other studies done on younger, female, or healthier populations have suggested an increased life span following these procedures.
But this current study looked at an older, predominantly male, and sicker group of adults, and the results did not show a decrease in mortality rates in patients after gastric bypass surgery during a nearly seven-year follow-up period.
"We looked at Roux-en-Y gastric bypass because that was the predominant procedure done when the research was conducted," says study researcher Matthew Maciejewski, PhD, an investigator at the center for Health Services Research in Primary Care at the Durham Veterans Affairs Medical Center in Durham, N.C.
The research appears in the June 15 issue of the Journal of the American Medical Association.
Weight Loss Surgery and Risk of Death
Researchers analyzed data from 850 veterans who had weight loss surgery between January 2000 and December 2006 at one of 12 VA medical centers and a similar number of severely obese high-risk veterans who did not have the operation but received their health care from the same facilities. Among the surgical patients, 74% were male and 26% were female. Their average age was 49 and the average body mass index (BMI) was 47, which is considered severely obese.
When researchers compared mortality rates in the surgical group to a matched nonsurgical control group -- who had a similar age, BMI, race, gender mix, marital status, and number of participants who were super-obese (BMI of 50 or above) -- they did not find a lower mortality rate.
Why didn't gastric bypass extend life? Maciejewski says one possibility is that there is no survival benefit from weight loss surgery in this higher-risk, predominantly male group of patients after nearly seven years. A second explanation is that there could be a longer-term benefit that researchers didn't have enough time to observe.
A study from Sweden with a longer follow-up period found a survival benefit in patients, but it was not seen until an average of 13 years after weight loss surgery.
"In the Swedish research, some of the decreases in mortality found a decade or more later were caused by a reduction in deaths from cancer and heart disease," says Janey Pratt, MD, a bariatric surgeon and director of the Massachusetts General Hospital Weight Loss Center in Boston, who was not involved in either of the two studies. "Perhaps in this latest research, the damage had already been done in older patients, and they're less likely to reap the benefits of surgery in terms of survival.”
Eleven of the 850 surgical patients died within a month of having gastric bypass. That's a mortality rate of 1.3%, which is four times higher than the one seen in an earlier study of weight loss surgery in younger, mostly female patients.
Pratt tells WebMD that it's much more difficult to do obesity surgery on male patients than females because of gender differences in the way fat is distributed on the body.
Women carry more of their fat in their hips and thighs, and belly fat is found mainly in the abdominal wall. But extremely obese men carry much of their fat in the belly, the so-called "apple" shape. They have thin abdominal walls but lots of fat floating around inside surrounding the gastrointestinal tract and organs where weight loss surgery takes place.
Weighing Risks and Benefits of Obesity Surgery
Roughly 220,000 Americans have obesity surgery per year, or 1% of the clinically eligible population, according to the American Society for Metabolic and Bariatric Surgery. These operations, which include gastric bypass or gastric banding, make the stomach smaller so the amount of food eaten is reduced. With gastric bypass, fewer calories are also absorbed because food bypasses part of the small intestine.
"Even though this study did not suggest a survival benefit at nearly seven years, there are a host of other benefits from having bariatric surgery," Maciejewski tells WebMD. It's effective in producing weight loss, it decreases the use of medication for obesity-related health conditions, such as diabetes, high blood pressure, and high cholesterol, and it improves the quality of life.
Pratt frequently does weight loss surgery in people over 60, but she tells her patients that it's unlikely to prolong their life and more likely to improve their quality of life and decrease the number of medications they're currently taking.
Many go ahead and have the procedure. "But sometimes it's the quality of life benefits -- being able to sleep in the same bed as their spouse, sitting comfortably in a movie theater, or cutting their own toenails -- that's enough. It doesn't have to be living longer," says Pratt.