Missing Link Found: Bariatric Surgery Reduces Mortality

GOTHENBURG, Sweden, Aug. 22 -- Two research groups have provided long-awaited evidence that bariatric surgery saves lives, up to 136 per 10,000 operations.
Gastric bypass reduced all-cause mortality 40% in a study of severely obese American patients, and bariatric surgery of whatever type reduced morality 29% in a Swedish study. The results of both studies were reported in the Aug. 23 issue of the New England Journal of Medicine.
Weight loss has been well documented to reduce mortality risk factors, including incident diabetes, commented George A. Bray, M.D., of Louisiana State University, in an accompanying editorial.
But, he noted, some epidemiologic studies have suggested shedding pounds may worsen life expectancy, possibly from confounding by unintentional loss.
For a more conclusive answer, Lars Sjöström, M.D., Ph.D., of Gothenburg University here, and colleagues, conducted a prospective controlled trial.
Their Swedish Obese Subjects study included 2,010 patients who underwent bariatric surgery and 2,037 matched controls who didn't want surgery and received whatever treatment was customary at the center where they registered. This ranged from intensive lifestyle intervention and behavior modification to no treatment.
Most of the surgeries were vertical banded gastroplasties (68%). The rest were split between nonadjustable or adjustable banding similar to the lap band (19%) and gastric bypass (13%).
Participants were age 37 to 60 at enrollment from 1987 to 2001. The minimum eligible body mass index (BMI) was 34 for men and 38 for women, which was chosen before the 1991 NIH Consensus Conference recommended a cutoff of 40 (35 for patients with coexisting illnesses).
After an average of 10.9 years of follow-up and with an impressive 99.9% follow-up rate, there were 129 deaths in the control group and 101 in the surgery group. The most common causes were MI and cancer.
After adjustment for sex, age, and risk factors, all-cause mortality was 29% lower for the surgery group than for the controls (hazard ratio 0.71, P=0.01).
But because the Swedish study included primarily vertical banded gastroplasty, which is no longer commonly used, Ted D. Adams, Ph.D., M.P.H., of the University of Utah in Salt Lake City, and colleagues, looked at long-term mortality with gastric bypass surgery.
Their study included a series of 7,925 gastric bypass surgeries done from 1984 through 2002 at a single center in Utah. These cases were matched to 7,925 randomly selected control adults with a BMI of 35 or higher based on height and weight self-reported on Utah driver's license and identification card applications.
The researchers gathered data from the National Death Index and the Utah Cancer Registry.
After a mean of 7.1 years of follow-up, the adjusted death rate was 40% lower with surgery than without it (hazard ratio 0.60, 95% CI 0.45 to 0.67, P<0.001).
For specific causes, the death rates with gastric bypass versus without the surgery were:
52% lower for all diseases combined (P<0.001)
92% lower for diabetes (P=0.005)
59% lower for coronary artery disease (P=0.006)
60% lower for cancer (P=0.001)
The reduction in cancer-related deaths was surprising, the researchers said, but suggested it may be related to improved cancer screening with weight loss.
Not all the results were postitive, however. Deaths from suicide, accidents, poisonings, and other nondisease causes were 1.58 times more common among surgical patients than among controls (P=0.04).
This warrants research into "the possible need for psychological evaluation and psychiatric treatment before surgery, and aggressive follow-up after surgery," the researchers wrote.
Nevertheless, the net effect was prevention of 136 deaths per 10,000 operations, they said.
Early death rates contrasted in the two studies. In the Swedish study, early death -- occurring within 90 days of the surgery for either the patient or his matched control -- was substantially more common in the surgery group than among controls (0.25% versus 0.10%). In the U.S. study, deaths occurring in the first year were similar between groups (0.53% versus 0.52%).
But, overall the findings may argue that it is time to reevaluate BMI guidelines for bariatric surgery, Dr. Bray said in his editorial comment.
"The question as to whether intentional weight loss improves life span has been answered," he concluded, "and the answer appears to be a resounding yes."
Primary source: New England Journal of MedicineSource reference: Sjöström L, et al "Effects of Bariatric Surgery on Mortality in Swedish Obese Subjects" N Engl J Med 2007;357:741-52. Additional source: New England Journal of MedicineSource reference: Adams TD, et al "Long-Term Mortality after Gastric Bypass Surgery" N Engl J Med 2007;357:753-61.