Public Release: 

Overweight Patients At Greater Risk Of Infection After Surgery

Ohio State University

COLUMBUS, Ohio -- Surgery patients who are overweight are about six to nine times more likely to develop post-operative infections than patients who are not overweight, new research suggests.

In a study of patients who had elective surgery at Ohio State University over a three-month period, researchers found that 2.8 percent of the overweight and 4 percent of the severely overweight patients developed post-operative infections while in the hospital. Conversely, only 0.5 percent of the normal weight patients developed such infections. The overweight and severely overweight patients were not any more ill to begin with than the normal weight patients.

"There was a significant increase in the number of hospital-acquired infections in the obese populations," said Patricia Choban, an assistant professor of surgery at Ohio State and lead author of the study. "These results support the increasing body of evidence suggesting that obese patients may be at increase drisk for infectious complications around surgery, particularly wound complications."

Obesity is currently the most prevalent chronic disease in the United States, Choban said, with nearly 35 percent of the U.S. population affected.

Choban conducted this research with Rachel Heckler, graduate student; Jean C. Burge, a patient care resource manager in general surgery; and Louis Flancbaum, an associate professor of surgery, all from OhioState. The group's work was published in a recent issue of The American Surgeon.

For the study, Choban and her colleagues reviewed the anesthesia records of 849 patients who had general, urologic, gynecologic or thoracic surgery at Ohio State University Hospitals between October 1 and December 31, 1991. These records included the height, weight, age, gender and body mass index (BMI) of each patient, as well as the anesthesiologist's estimate of the severity of the patient's disease.

The researchers then reviewed hospital epidemiology records to determine how many of these patients acquired infections while they were hospital inpatients.

The results:

  • Of the patients in the study, 63 percent were categorized as normal weight (BMI under 27 kilograms/square meter), 21 percent were categorized as obese (BMI 27 to 31 kilograms/square meter) and 16 percent were categorized as severely obese (BMI over 31 kilograms/square meter).
  • Age and health conditions were similar among all three groups of patients.
  • However, patients who were obese had a rate of infection nearly six times higher than that of their normal weight counterparts. Severely obese patients were similarly affected, with a rate of infection nearly nine times that of their normal weight counterparts.
  • Obese and severely obese patients, however, had no greater mortality rates after surgery than the regular weight patients. Among the regular weight patients, 1.1 percent died after surgery; among the obese, 1.7 percent died; among the severely obese, 1.4 percent died. Scientists aren't yet sure why overweight surgical patients have an increased risk of infection. However, Choban said, there are several hypotheses. Fat tissue, in general, has poor resistance to infection, she said. In addition, obese patients tend to have problems maintaining appropriate blood sugar levels, even if they're not overtly diabetic, and this can contribute to impaired wound healing and immune system dysfunction. Further, Choban said, longer operative times due to the size of overweight patients might contribute to the development of wound problems. Choban said there are two messages she hopes overweight people who are facing surgery will take away from this study. "Patients need to understand that while the doctors are going to do everything they can, there's going to be a higher risk of infection. They need to understand what they're getting themselves into. They have a greater chance of being in the hospital longer than patients who aren't overweight -- even if everything goes perfectly with the surgery." At the same time, they need to know that their risk of dying doesn't appear to be any higher than normal weight patients. Some overweight patients are told they'll die if they have an operation. Our study found no evidence to support that; the increase in infectious complications was not associated with an increase in patient mortality. Obese patients should be offered surgical treatment for their disease when surgery is the most appropriate therapy. Obesity is not a contraindication to an appropriate surgical operation."

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