Extreme obesity proved a risk factor for mortality during CABG surgery. (Rise in Renal Failure, Time on Ventilator).

FORT LAUDERDALE, FLA.--Extremely obese patients who undergo coronary artery bypass grafting are at a greatly increased risk of operative mortality and perioperative complications compared with moderately obese and nonobese patients.

Although previous smaller studies identified obesity as a risk factor, Dr. Ganga Prabhakar and his colleagues at West Virginia University in Morgantown are the first to compare enough patients to show which subpopulation is at greatest risk for adverse outcomes.

Sternal wound complications were the only previously proven adverse outcome, Dr. Prabhakar reported at the annual meeting of the Society of Thoracic Surgeons. However, he and his associates demonstrated that extremely obese patients are also at risk of increased renal failure, time on a ventilator, and length of hospital stay greater than 14 days.

The implications are important with 97 million overweight adults in the United States. Direct annual costs associated with obesity are estimated at $51.6 billion. In addition, Dr. Prabhakar said, many thoracic surgeons perceive all obese patients as having a poor prognosis after coronary artery bypass graft (CABG), which may not be the case.

Researchers used the Society of Thoracic Surgeons National Cardiac Surgery Database to identify 197,105 isolated, primary CABG procedures between January 1997 and December 2000. Of these, 136,310 patients had a body mass index (BMI) between 18 and 25, which National Institutes of Health guidelines define as normal. Another 42,060 patients were classified as moderately obese, with a BMI of 35 to 40. The third group ...