ASA: Scale Predicts Mortality in Weight-Loss Surgery

COLORADO SPRINGS, Colo., April 27 -- For prospective gastric bypass patients, surgeons may have a better tool to help gauge the risk of mortality from the procedure, researchers said here.

In what the investigators called the first scoring system validated for clinical use, patients with a high risk score were 12 times more likely to die than those in the low-risk group, while those in the medium-risk group were six times more likely to die, found Eric DeMaria, M.D., of Duke, and colleagues.

The system -- which takes weight, gender, age, blood pressure, and pulmonary embolus risk into consideration -- was assessed in a multicenter study of 4,431 bariatric-surgery patients, the investigators said at the American Surgical Association meeting.

"Until one can predict risk, it's hard to do risk reduction, which would be the ultimate goal of a scoring system," Dr. DeMaria said. "It's an important step forward."

To predict mortality risk, preoperative patients were given one point for each risk factor (body mass index 50 kg/m² or higher, male gender, hypertension, pulmonary embolism risk, and age 45 or older).

Pulmonary embolism risk was defined by previous deep vein thrombosis or pulmonary embolism, prior use of an inferior vena cava filter, obesity-hypoventilation syndrome, and right heart failure.

Those with no more than one point were considered to be in the lowest "A" risk group. Those with two or three points were in the intermediate "B" risk group. A score of four or five points was classified as high-risk ("C").

"We think the strength of our scoring system is how easy it is to figure out even in your first conversation with a prospective patient," Dr. DeMaria said.

To validate this previously published scale, the researchers retrospectively determined risk scores for 4,431 consecutive patients at three university medical centers and a private practice who underwent gastric bypass surgery.

Their findings:

• Overall mortality was 0.7%, with mortality in each risk class statistically different from the other two groups (P<0.05).
• Among the 2,166 low-risk patients, five died (0.2%).
• Among the 2,140 intermediate-risk patients, 25 died (1.2%).
• Among the 125 high-risk patients, three died (2.4%).
• The medium-risk group accounted for 48% of the cohort and 76% of the deaths whereas the high-risk group represented 3% of the cohort but a disproportionate 9% of the deaths.

The study was limited by a lack of detailed demographic data, including whether the surgeries were laparoscopic or open, and by a lack of data on surgical complications.

"There's this general feeling that patients should not pursue bariatric surgery until they have failed everything else," Dr. DeMaria said. "That concept really does not make sense when you look at the risk stratification score."

From a public health perspective, he said, patients should be treated when they are younger, healthier and thus at lower mortality risk. The only risk factor that cannot be controlled is gender, he noted.

"It even more strongly argues that male patients should be operated on when they are younger and healthier to keep them in that class 'A' low-risk group," Dr. DeMaria said.

He cautions, however, that the findings should not be used as exclusion criteria for weight-loss candidates.

"I think it's a mistake to believe that higher risk for surgery doesn't make a patient a candidate for surgery," he said.

The highest risk patients likely have higher mortality risk even without surgery, he said.

"We don't yet have enough information to figure that all out, but I think it's premature to say that the high risk group shouldn't be candidates at all," he said. "There is no other effective and durable treatment for morbid obesity."

Rather, Dr. DeMaria suggested using a high risk score as impetus for preoperative risk reduction.

"The one strategy many centers are pursuing is weight reduction before surgery or picking a lower risk surgery rather than the gastric bypass surgery first, such as Lap-Band or sleeve gastrectomy," Dr. DeMaria said.

"If you get some weight loss, perhaps you can convert patients from high risk to intermediate risk and have a better outcome," he continued.