Fewer surgical infections seen in patients over 65.
The finding surprised the investigators, who were led by Keith S. Kaye, M.D., of the division of infectious diseases at Duke University Medical Center, Durham, N.C.
"It is possible that, in contrast to younger patients, older patients who are at increased risk of postoperative complications (e.g., frail elderly patients with multiple comorbid conditions) less frequently undergo surgery than do their healthy peers, because clinicians and/or patients judge their risk of adverse clinical outcomes to be too high," the investigators wrote. In addition, they hypothesized, "Persons who survive to much older ages may have a genetic makeup that enables them to better withstand threats to health than some middle-aged persons."
Dr. Kaye and his associates studied the medical records of 144,485 patients aged 17-108 years who underwent surgical procedures at 11 hospitals in the United States between February 1991 and July 2002 (J. Infect. Dis. 2005;191:1056-62). They used Centers for Disease Control and Prevention criteria to identify surgical site infections and randomly divided patients into two cohorts: a derivation cohort (N = 72,143) and a validation cohort (N = 72,342).
Of the 144,485 patients, 1,684 developed a surgical site infection, for a rate of 1.2%. Gastrointestinal procedures carried the highest rate of surgical site infection (3.1%), followed by cardiothoracic and vascular procedures (2.3% and 1.7%, respectively). The mean age of patients who developed a surgical site infection was 57.1 years, while the mean age of those who did not was 52.3, a difference that was statistically significant.
Analysis of the derivation cohort revealed that the risk of surgical site infection increased 1.1% per year between the ages of 17 and 65. However, beginning at age 65, the risk of infection decreased by 1.2% for each additional year of age.
Analysis of the validation cohort revealed similar findings.
The work is "a well-done study with a very large cohort," James Markmann, M.D., attending surgeon at the Hospital of the University of Pennsylvania, Philadelphia, said in an interview.
"I think the conclusions that are drawn from the study are stronger than what has been possible from prior studies. The most interesting aspect was the notion that there is an increase in risk [of surgical site infection] with increasing age, but after age 65 the risk seems to go down. It allows you more information in terms of what the real risk is, based on the age of the patient," he said.
BY DOUG BRUNK
San Diego Bureau
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|Publication:||Internal Medicine News|
|Date:||Jul 15, 2005|
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