Duke surgeon develops first strategy to determine odds of procedure-related mortality

By Jeni Baker

If you’re thinking about pursuing weight-loss (bariatric) surgery, you and your family can now make a more informed decision, thanks to a new assessment system that can accurately predict one’s risk of dying from such a procedure.

The simple scoring system, known as the Obesity Surgery Mortality Risk Score (OS-MRS), measures a person’s perioperative risk, or the risk of death from the time surgery begins until 30 days after it is performed – which, no matter how small, is inherent to all types of surgery and anesthesia use.

Eric DeMaria, MDDeveloped by Eric DeMaria, MD, director of the Duke Weight Loss Surgery (WLS) Program at Durham Regional Hospital, the OS-MRS shows that patients with one or more of these five factors are at increased risk for death related to weight-loss surgery:

• Body mass index of more than 50 -- Body mass index (BMI) measures body fat based on a person’s weight and height. A BMI of 30 and above is considered obese, and obese people are at greater risk for any surgery.
• High blood pressure -- People with high blood pressure (hypertension) often suffer from heart disease and/or chronic blood vessel inflammation, both of which increase the odds of serious surgery-related complications.
• Age 46 or older -- As with most operative procedures, people older than 45 are known to be at higher risk for death related to surgery.
• Risk of blood clot in the lungs -- People who have previously had a blood clot in their lungs (pulmonary embolism) or legs, or who are genetically at risk for developing blood clots are at elevated surgical risk. All patients, regardless of their risk for clotting, are prescribed blood-thinning medications prior to surgery.
• Male gender -- Men are more likely than women to suffer from certain conditions that can increase surgical risk. These include diabetes, hypertension and metabolic syndrome (also known as syndrome X or insulin resistance syndrome), a condition characterized by a group of risk factors including hypertension, high triglyceride levels, low HDL levels and high blood sugar levels after fasting.

The OS-MRS enables physicians to readily determine whether a person’s risk of dying from bariatric surgery is low, medium or high. Patients with none or one of the five factors are considered to be at low risk for death, those with two or three factors are deemed medium-risk, and those with four or five factors are considered to be at high risk.

The OS-MRS has been validated in a study of 4,433 patients who underwent bariatric surgery at the University of South Florida and the Medical University of South Carolina, as well as at a private practice in Scottsdale, Ariz.

The study yielded the following data:

• Of the 2,166 patients deemed low-risk by the scoring system, eight died.
• Of the 2,142 patients in the medium-risk group, 26 died.
• Of the 125 high-risk patients, three died. While these patients represented less than three percent of the people studied, they accounted for eight percent of the deaths.

In other words, high-risk patients are six times more likely to die than low-risk patients, while those in the medium-risk group were three times more likely to die than low-risk patients.

“The OS-MRS gives surgeons concrete data they can use in surgical decision-making, as well as in their discussions with patients,” says DeMaria. “The system also provides standardization of surgical outcomes, making comparisons among surgical centers more meaningful.”

Although OS-MRS was devised to assess patients’ risk for the Roux-en-Y gastric bypass -- which some 170,000 U.S. patients underwent in 2005, according to the American Society for Bariatric Surgery – the risk information it provides may be applicable to other types of weight-loss surgery, as well, says Aurora Pryor, MD, also a member of Duke’s WLS team.

“Severely obese people – those who are candidates for bariatric surgery – tend to be at higher risk for any surgery than patients who are not obese,” says Pryor. “And patients at the greatest risk for bariatric surgery also have the highest risk for dying from obesity-related conditions.”

However, Pryor says, because risk averages are just that, they don’t necessarily apply to each individual. Therefore, even severely obese people determined to be at high risk for bariatric surgery may still be able to undergo such a procedure. And, according to DeMaria, compared to doing nothing, surgery may actually be the better choice for those people.

“Many physicians and patients see bariatric surgery as an option to use only when all other approaches to weight loss have failed,” DeMaria says. “However, the OS-MRS shows that this strategy may need to be reconsidered.”

“If patients put off surgery while they attempt other weight-loss therapies that ultimately don’t work, over time, they can move into a higher-risk category as they gain more weight, get older or develop hypertension or other conditions that increase the danger of surgery,” he continues. “In these cases, delays can make surgery even riskier.”

High-risk patients, DeMaria says, have several options for reducing their risk of gastric bypass surgery.

• One is to undergo a series of smaller, less dangerous risk-reduction procedures – such as the sleeve gastroectomy – before opting for a more complex bariatric surgery, such as gastric bypass. (A restrictive stapling procedure than often can be performed laparoscopically, the sleeve gastroectomy removes a portion of the stomach and transforms the shape of the remaining stomach from sac-like to narrow and tubular.)
• Another option is to lose weight prior to the higher-risk procedure. While some severely obese people are able to lose enough weight by traditional means (such as diet and exercise) to improve their health, most are unable to keep the weight off. The key, says Pryor, is to undergo surgery when weight is on a downswing.

Duke’s WLS Program – recognized as a Center of Excellence by the American Society for Bariatric Surgery – is now using the OS-MRS during initial patient evaluations. To learn more, call 919-660-2229.