How to Predict Obesity Surgery Risk
New Method Lets Doctors Identify Which Patients Are at High Risk for Death
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
The observations led them to conclude that these five factors are
independent predictors of poorer surgical outcome:
- Being male
- Age over 45
- Having a body mass index of more than 50
- Having high blood pressure
- Having a high risk for developing blood clots in the lungs
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
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
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
"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."