The study was led by a team of researchers from the University of Utah School of Medicine and LDS Hospital.

The 14-year study evaluated 15,850 severely obese patients, half of whom underwent gastric bypass surgery to reduce their weight. The mortality rate from coronary heart disease was 56 percent lower in the surgery group than in the non-surgery (control) group. The surgery group also showed a 60 percent lower death rate from cancer and a 92 percent lower death from diabetes than the non-surgery group, according to Ted D. Adams, Ph.D., M.P.H., the study's lead author,

Adams is a professor in the Division of Cardiovascular Genetics at the University of Utah School of Medicine and co-founder of the Intermountain Health and Fitness Institute at LDS Hospital in Salt Lake City.

While mortality rates for specific diseases were lower in the surgery group, Adams said mortality rates from other causes such as accidents and suicide were 58 percent higher among those who had the weight loss surgery than the control group.

This study helps to further define the effects of gastric bypass surgery on long-term mortality. Reduction in death by any cause, and disease-specific deaths such as coronary heart disease, diabetes, and cancer were significantly reduced in surgery patients compared to the non-surgical control group, he said.However, rates of death not caused by disease were shown to be greater in those who underwent the weight-loss surgery when compared to controls.

The paper suggests at least some of these non-disease deaths in the surgery group may be due to unrecognized pre-surgical mood disorders or post-traumatic stress disorders, which appear to be more common in severely obese patients. Adams said the research shows the need for better methods of evaluating candidates for the surgery, including the possible need for psychological evaluation and psychiatric treatment before surgery, and aggressive follow-up after surgery.

The reduced mortality for any cause of death is likely related to significant health improvements that follow gastric bypass surgery, such as reduced blood pressure, improved or resolved diabetes, and reduced sleep apnea, says Adams.

Women accounted for 84 percent of the patients involved in the study.

The average body mass index (BMI), which is calculated by dividing a person's weight in kilograms by the square of the person's height, for patients in the surgery group was 45.3, and 46.7 for the non-surgery group.

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