How to Predict Obesity Surgery Risk

New Method Lets Doctors Identify Which Patients Are at High Risk for Death

From the WebMD Archives

April 27, 2007 -- About 200,000 Americans will have weight loss surgery this year, and while most will go on to lead healthier lives, tragically, some patients will die as a result.

Now a new assessment tool developed by a Duke University gastric bypass surgeon should help doctors better identify patients with the lowest and highest risk of death.

Eric DeMaria, MD, and colleagues first proposed the risk assessment system last year, based on their own observations and those of others in the field.

The observations led them to conclude that these five factors are independent predictors of poorer surgical outcome:

Patients with none or one of the risk factors were considered to have a low risk of death from weight loss surgery. Those with two to three factors fell into the medium-risk range, and those with four or five were considered high risk.

In an effort to validate the system, DeMaria and colleagues examined data from 4,433 patients who had weight loss surgeries at three centers.

DeMaria presented findings from the study at the annual meeting of the American Surgical Association in Colorado Springs, Colo.

He reported that surgery-related deaths occurred in eight of the 2,166 patients classified as low risk, 26 of the 2,142 patients in the medium-risk group, and three of the 125 patients classified as high risk.

While high-risk patients made up less than 3% of the total surgical population, they had a sixfold greater risk of death than patients categorized at the lowest risk who had no risk factors.

How Many Die?

It is not clear how many patients who have weight loss surgeries ending up dying from the procedures. A recent government report found death rates immediately following surgery to be 0.19% in 2004 -- down from 0.89% just six years earlier.

But a 2005 study of Medicare recipients who had weight loss surgeries found a 5% risk of death among patients aged 65 and older within 30 days of surgery and a 3.7% risk of death for men.


What is clear is that many more people are having gastric bypass surgery than even just a few years ago.

"Prior to 1995, only about 10,000 surgeries were performed each year, and now we are up to about 200,000 [annually]," American Society for Bariatric Surgery President Philip R. Schauer, MD, tells WebMD.

Schauer calls the new risk assessment model a good starting place, but he says it is far from a complete list of factors that could influence surgical outcome.

"These researchers were able to identify five important risk factors, but there may be 20 or more," he says. "For example, patients with cirrhosis might have very poor surgical outcomes, but we would need bigger studies to figure this out because cirrhosis is relatively rare."

'No Big Surprise'

The risk assessment tool can help patients better understand their specific risk. But DeMaria and Schauer agree that being 'high risk' doesn't mean that a patient should not have weight loss surgery.

In fact, these are the patients who could benefit most, they say, because their risk of death is already so high.

"It is no big surprise that these patients have a high surgical risk," DeMaria tells WebMD. "These are the patients who more than likely have co-morbid conditions like diabetes and cardiovascular disease, so their nonsurgical risk is probably pretty high, too."

Schauer cites a recent study that followed gastric bypass patients for eight years after surgery and compared them to morbidly obese people who did not have weight loss surgery. Even with surgical deaths, the bypass patients had a 65% lower mortality rate.

"When patients talk to their doctors about the risks of having surgery, they also need to talk about the risks of not having surgery," he says.

The Earlier the Better?

The observations could also be used to reassure patients who fall into the low-risk category and to help patients and their doctors assess the impact of delaying surgery, DeMaria says.

The mortality rate among low-risk patients in his newly reported study was 0.2% to 0.3%.

"That is very, very low risk," he says. "From a population standpoint it argues in favor of giving up the notion that people should be on death's door before they have weight loss surgery. It makes more sense to offer it to patients who are younger and healthier before they develop the health problems that are associated with the disease of obesity."

WebMD Health News Reviewed by Brunilda Nazario, MD on April 27, 2007


SOURCES: American Surgical Association annual meeting, Colorado Springs, Colo., April 26, 2007. Eric DeMaria, MD, director, Duke Endosurgery Center. Philip R. Schauer, MD, president, American Society for Bariatric Surgery; director, Bariatric and Metabolic Institute, Cleveland Clinic. Agency for Healthcare Research and Quality, Statistical Brief #23, Health and Human Services. JAMA, Oct. 19, 2005; vol 294.

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