By Dr Ananya Mandal, MD
A new study shows that weight loss surgery clearly cuts the risk of heart attacks, strokes and death from cardiovascular disease. But the research also raises questions regarding which patients benefit the most from surgery.
The study was published Tuesday in the Journal of the American Medical Association and is the first controlled clinical trial to measure the impact of bariatric surgery on heart health. The Swedish Obese Subjects study by Lars Sjöström and colleagues 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. Inclusion criteria were age 37 to 60 years and a body mass index of at least 34 in men and at least 38 in women.
Patients were recruited between September 1987 and January 2001. Date of analysis was December 31, 2009, with median (midpoint) follow-up of 14.7 years. Surgery patients underwent gastric bypass (13.2 percent), banding (18.7 percent), or vertical banded gastroplasty (68.1 percent), and controls received usual care in the Swedish primary health care system. Physical and biochemical examinations and database cross-checks were undertaken at preplanned intervals. The average changes in body weight after 2, 10,15, and 20 years were -23 percent, -17 percent, -16 percent, and -18 percent in the surgery group and 0 percent, 1 percent, -1 percent, and -1 percent in the control group, respectively.
Results showed 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.
Bariatric surgery was associated with reduced number of fatal heart attack deaths (22 in the surgery group vs. 37 in the control group), with analysis indicating that bariatric surgery was related both to reduced fatal heart attack incidence and total heart attack incidence. Also, bariatric surgery was associated both with reduced number of fatal stroke events and total stroke events.
Further look at 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 (a measure of both body weight and height).
Authors said patients with higher insulin levels before surgery experienced the greatest benefits from surgery. “High 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.
Dr. Mitchell Roslin, chief of obesity surgery at Lenox Hill Hospital in Manhattan, was not involved in the study but said the results show gastric bypass, Lap-Band and similar surgeries save lives. “This actually shows a survival benefit,” Roslin said. “The sad thing is that people are fighting for coverage for surgery. Patients have to go through so much prejudice to get a life-saving procedure.”
Other doctors say weight-loss surgery doesn’t live up to its marketing as a cure-all and may not be appropriate for some of the 200,000-plus Americans who get it every year.
Authors of the study concluded, “In conclusion, this is the first prospective, controlled intervention to our knowledge reporting that bariatric surgery is associated with reduced incidence of cardiovascular deaths and cardiovascular events. These results— together with our previously reported associations between bariatric surgery and favorable outcomes regarding long-term changes of body weight, cardiovascular risk factors, quality of life, diabetes, cancer, and mortality— demonstrate that there are many benefits to bariatric surgery and that some of these benefits are independent of the degree of the surgically induced weight loss.”