Obese patients at much greater risk for costly surgical-site infections

These infections, according to findings published in the journal Archives of Surgery, cost an average of $17,000 more per patient, extend hospital stays and leave patients at a three-times greater risk of hospital readmission.

"Obesity is a leading risk factor for surgical-site infections, and those infections truly tax the health care system," says Elizabeth C. Wick, M.D., an assistant professor of surgery at the Johns Hopkins University School of Medicine and the lead author of the study. "The burdens of caring for obese patients need to be better recognized."

To conduct the study, the Johns Hopkins team analyzed claims data from eight different Blue Cross and Blue Shield insurance plans for partial or total colon removal surgeries performed on adults ages 18 to 64 between 2002 and 2008. They identified 7,020 patients, 1,243 of whom were obese. The researchers looked at 30-day infection rates and calculated total costs from all health care claims for 90 days following surgery.

Colon surgery -- performed to treat colon cancer, diverticulitis and inflammatory bowel disease -- costs roughly $300 more per obese patient, whether an infection occurred or not. Obese patients also had slightly longer hospital stays, regardless of infection.

The average cost of caring for a patient with a surgical-site infection was $32,182 compared to $15,131 for each patient who didn't get infected. Those with infections stayed in the hospital for an average of 9.5 days compared to 8.1 days for those who did not contract one. The probability of hospital readmission in infected patients was 27.8 percent versus 6.8 percent in non-infected patients. When they had to be readmitted, those who had surgical-site infections stayed an average of two days longer than those without.

Not only are these findings relevant to physicians who need to pay special heed to infections in heavier patients but, the authors argue, to policymakers who plan to mandate public reporting of hospitals' surgical-site infection rates. Some insurers, meanwhile, have begun to withhold payment from hospitals when patients develop these complications and other insurers have discussed similar penalties. None of these plans take into account the higher infection rates found in obese surgical patients, Wick says.

Wick and her colleagues worry that punishing hospitals for surgical-site infections in obese patients could lead to discrimination, with surgeons shying away from operating on the heaviest patients for fear of financial loss and public shaming. Hospitals in 2012 will be required to publicly release surgical-site infection rates. If a hospital treated fewer obese patients, she notes, it would likely have fewer reportable infections.

"Pay-for-performance policies in surgery should account for the increased risk of infection and the cost of caring for this population," she says. "Failure to consider these differences can lead to perverse incentives that may penalize surgeons who care for obese patients and may even affect obese patients' access to surgery."

Thirty-four percent of adults in the United States are now estimated to be obese (those with a body mass index above 30), up from just 15 percent a decade ago.

Other study authors, all from Johns Hopkins, include Kenzo Hirose, M.D.; Andrew D. Shore, Ph.D.; Jeanne M. Clark, M.D., M.P.H.; Susan L. Gearhart, M.D.; Jonathan Efron, M.D.; and Martin A. Makary, M.D., M.P.H.