Gastric bypass surgery for severely obese patients increases their life expectancy significantly, according to research headed by Ted D. Adams of the University of Utah School of Medicine and LDS Hospital.
While their overall survival rate was higher, they were more likely to die of non-disease causes after the surgery.
The study, "Long-Term Mortality after Gastric Bypass Surgery," was published in the prestigious New England Journal of Medicine. It followed nearly 8,000 patients who had undergone gastric bypass surgery to reduce their weight. Eighty-four percent of the patients are women, and most are Utahns; all had their operations in this state between 1984 and 2002.
"We've matched the surgical patients with control subjects," Adams said in a telephone interview. "They were matched for age and gender and body mass index," with the patients' BMI calculated before the surgery. They also were matched with age at the time of surgery.
"We were able to match about 8,000 in each group," added Adams, who is a professor in the Division of Cardiovascular Genetics at the U. School of Medicine and a co-founder of the Intermountain Health and Fitness Institute at LDS Hospital, both in Salt Lake City.
Some of the subjects were followed for 16 years, some for as little as two. The result: dramatic proof that the surgery saves lives.
Deaths among the surgical group were 40 percent lower than those in the control group. The control group was selected through examining driver's license records, which record weight, height, age and gender.
"We looked at specific causes of death, and the surgical group (death rate) decreased about 56 percent for coronary artery disease, 92 percent for diabetes and 60 percent for cancer."
Links among diabetes, heart disease and obesity are well known. But the study indicates the sharp reduction in cancer deaths was surprising.
A strange finding is that the rate of deaths not caused by disease — such as accidents, suicide or poisoning — was 58 percent higher among patients who had the surgery.
A U. press release noted that some of these deaths might be because of mood disorders not recognized before the surgery, or post-traumatic stress disorders that seem to be more common in severely obese patients.
Could it also reflect the possibility that people with weight loss were able to get outside and become more active, and were more likely to be killed in accidents? "There's some speculation," Adams said.
"We know that people do become more active after they've had the surgery, and there's some speculation that people following gastric surgery, at least some of them, may have a tendency to have chemical abuse, that sort of thing, drink more alcohol."
The New England Journal of Medicine article cautions that part of the outcome may result from factors built into the study. All of the surgical patients had sought the operation; the control group was made up of large people who had not. Possibly the control group may have riskier lifestyles, as they had not sought surgery to control their weight.
Further research is needed to evaluate several features, Adams said. If psychological factors are involved in patient suicide or accidents, he said, patients may need more psychological evaluations and possibly aggressive follow-ups after gastric bypass surgery.
The study was part of larger research in which medical scientists have been following 1,200 people.
Authors of the report are Adams; Richard E. Gress and Steven C. Hunt of the U. medical school; Drs. Sherman C. Smith, R. Chad Halverson and Steven C. Simper of Rocky Mountain Associated Physicians, Salt Lake City; Antoinette M. Stroup, Utah Cancer Registry at the U.; Wayne D. Rosamond of the University of North Carolina at Chapel Hill; and Michael J. LaMonte of the University of Buffalo in New York.
E-mail: bau@desnews.com