ORLANDO – Patients undergoing bariatric surgery had a significantly reduced rate of subsequent myocardial infarctions and strokes and significantly increased survival, compared with similar, morbidly obese patients who had other types of surgery, in a retrospective cohort study of more than 9,000 U.S. patients.
The results "add to the growing evidence that bariatric surgery plays a role in temporizing the risk factors for major cardiovascular events. We believe our analysis builds on prior reports and takes them a step further by evaluating actual events," Dr. John D. Scott said at the annual meeting of the American Society for Metabolic and Bariatric Surgery.
In his study of bariatric surgery patients in South Carolina during 1996-2008, the combined rate of MIs, strokes, and deaths was 52% below the rate in patients undergoing gastrointestinal surgery, and 28% below the rate of those who had orthopedic surgery – both statistically significant differences. The results also showed significant drops in each component of the combined end point (MIs, strokes, and deaths).
"Previous literature demonstrated that cardiovascular risk declined after bariatric surgery. What this study did was look at the rate of actual cardiovascular events, which significantly declined after bariatric surgery," said Dr. Scott, a bariatric surgeon at University Medical Center Greenville (S.C.) Hospital System.
The new study used hospital in-patient records collected during 1996-2008 through the South Carolina Office of Research and Statistics, and death data collected by the South Carolina Department of Health and Environmental Control. The analysis included morbidly obese patients aged 40-79 years who underwent nonemergency surgery (4,747 patients who had any form of bariatric surgery, 3,066 patients who underwent joint replacement or spinal surgery, and 1,327 patients who had a cholecystectomy, hernia repair, or lysis of gastrointestinal adhesions). Those with a history of prior MI or stroke were excluded.
Patients were followed for an average of 14 months after bariatric surgery, 25 after orthopedic surgery, and 26 months after gastrointestinal surgery.
In a multivariate analysis that controlled for age, sex, race, hypertension, dyslipidemia, diabetes, coronary artery disease, obstructive sleep apnea, and a history of transient ischemic attack, patients undergoing bariatric surgery had a significant 41% reduced rate of first MI compared with the orthopedic surgery patients, and a significant 51% lower rate compared with the gastrointestinal surgery patients.
Mortality in the bariatric surgery patients dropped by a significant 19% and 55% relative to the orthopedic and gastrointestinal patients, respectively, and the stroke rate was also significantly lower following bariatric surgery compared with the rates in each control group. The magnitude of these event-rate reductions was consistent with prior reports of risk reduction, Dr. Scott said.
Notably, bariatric surgery "reduced cardiovascular events, as opposed to obesity-drug treatments that may actually increase the risk for cardiovascular events," he noted. "Bariatric surgery has been rigorously tested and [proved] over the past 20 years, and it has a dramatic effect on all aspects of patient health. [Most] medical treatments for obesity don’t have 20 years of data, and some medications actually cause heart problems. We don’t know how bariatric surgery reduced myocardial infarctions and strokes, but it’s probably several factors: weight loss and resolution of diabetes, hypertension, and sleep apnea. The spectrum of returning patients to a more normal, baseline state probably leads to less morbidity and mortality," Dr. Scott said.
Dr. Scott said that he has been a speaker for Gore.