One important finding of the study was that gastric banding was a slightly safer form of the operation, and should be used for patients at higher risk of complication, Wolfe said, adding that the study could guide doctors when informing patients of the risks.
"If we just give them the average ... that's fair enough," Wolfe said. "But suppose the patient has all four of the risk factors that we are talking about and they have to have the higher risk procedure, then it really is inaccurate to tell that patient that their risk is the same as the average patient."
Dr. Philip Schauer, past president of the American Society for Metabolic and Bariatric Surgery and a professor of surgery at the Cleveland Clinic Lerner College of Medicine, said the study will help inform patients and doctors of risks in the future.
"Surgery is quite safe, considering the relatively high risk of these severely obese patients," he said, noting that coronary bypass surgery carries a risk of death 10 times greater than the risk this study found for bariatric surgery.
"For that mortality risk, a patient is receiving a great deal of benefit from that," he said.
Schauer was a participating doctor in the early days of the study, as he performed surgeries at the University of Pittsburgh -- one of the centers involved.
Calling the study "an excellent start," Dr. Christine Ren Fielding, an associate professor of surgery at New York University Langone School of Medicine, said the study gives doctors more information they want about the procedure.
"This is only the very first answer of many questions that we have regarding bariatric surgery," she said. "This study is focused on a very specific question: What is the short-term (30-day) mortality and complication rate of bariatric surgery."
For Dr. Eric J. DeMaria, director of endosurgery and bariatric surgery at Duke University, that short-term risk is a critical step in assessing risk.
"Most risk accompanying a surgical intervention is demonstrated to occur in the short term following the procedure," he said.
"The very low mortality of bariatric procedures found in this study are consistent with several recent publications which confirm that risk of complications and mortality of bariatric surgery has decreased significantly," said DeMaria.
For Verhelst, the risk calculations were not that hard, even after she was informed.
"I just read [about the surgery]," she said. "Of course, like I said, you have to know the risk. You have to know what could and could not happen."
But the risks did not sway her.
"You either be fat for the rest of your life or you make some changes," Verhelst said.
She said she looked ahead and underwent surgery because she wanted to avoid becoming another family member with diabetes or heart disease.
"I knew if I stayed on that path I would have one or more of those problems," she said.
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