Weight-loss surgery reduces the risk of heart attacks and strokes. (Joseph Daniel Fiedler /…)
Weight-loss surgery clearly cuts the risk of heart attacks, strokes and death from cardiovascular disease, a new study shows. But the research also raises questions regarding which patients benefit the most from surgery.
The study, published Tuesday in the Journal of the American Medical Assn., is the first controlled clinical trial to measure the impact of bariatric surgery on heart health. The Swedish Obese Subjects study compared 2,010 middle-aged, obese people who had weight-loss surgery with 2,037 similar obese people who received normal medical care, which usually included counseling on lifestyle choices that affect weight. The participants were followed for an average of 14.7 years.
Researchers found that weight-loss surgery reduced the chances of dying from heart disease or having a non-fatal heart attack or stroke. In the surgery group, 28 cardiovascular deaths were recorded compared with 49 in the control group. Overall, there were 199 cardiovascular events in the surgery group compared with 234 in the control group.
However, further analysis of the data showed that the amount of weight people lost wasn't related to their later risk of cardiovascular problems. This perplexing finding could be the result of the way the study was designed. But it's also possible that the impact of bariatric surgery on heart health is tied to other factors besides body mass index.
For example, the authors said, patients with higher insulin levels before surgery experienced the greatest benefits from surgery. "[H]igh insulin may be a better selection criterion for bariatric surgery than high BMI, as far as cardiovascular events are concerned," they wrote.
An editorial accompanying the study notes that patients are typically referred for weight-loss surgery based on their BMI. But, "twenty years later, outcome studies of bariatric surgery have shown that the benefits of bariatric surgery are not that straightforward," wrote the author of the commentary, Dr. Edward H. Livingston of University of Texas Southwestern Medical Center in Dallas. For example, he said, people with abdominal obesity may be at higher risk for heart problems than people with higher fat mass in the trunk and legs. It may be time for experts to reconsider the criteria for recommending bariatric surgery, he said.
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