Study Validates Classification Of Diabetic Foot Infections

A system for classifying diabetic foot infection proved effective at predicting adverse clinical outcomes in a 2-year cohort study, reported Lawrence A. Lavery, D.P.M., of Scott \& White Hospital, Round Rock, Tex., and his associates.

In 2004, the Infectious Diseases Society of America (IDSA) and the International Working Group on the Diabetic Foot (IWGDF) each published guidelines for managing diabetic foot infections. Both sets of guidelines included "essentially identical" systems for classifying the severity of infection. In contrast, previous guidelines "either did not specifically define infection or, if they did, only noted its presence or absence," the researchers said (Clin. Infect. Dis. 2007 Jan. 17 [Epub DOI:10.1086/511036]).

Both of the 2004 classification systems first categorize foot wounds as infected or not, based on the presence or absence of purulent secretions or local or systemic signs of inflammation or infection. They further categorize infections as mild, moderate, or severe based on wound depth and size (especially the extent of cellulitis) and on the presence or absence of systemic manifestations of infection, such as fever, chills, leukocytosis, or metabolic aberrations.

The new classification systems were developed by "an international consensus of experts in various fields," but until now no study has validated their ability to predict outcomes. Dr. Lavery and his associates did so by applying the classification systems to data that had already been collected on 1,666 subjects enrolled in a foot-care management program and followed for a mean of 27 months.

A total of 247 patients (14.8%) developed a foot wound and 151 (9.1%) developed a foot infection. Of the foot infections, 27 were classified as severe, and 50 patients required an amputation of some type. "Considering that these patients were screened for foot disorders at enrollment in the study, were educated about proper foot care, and had ready access to a foot clinic, we observed a higher incidence of foot infection than expected," the investigators noted (Clin. Infect. Dis. 2007;44:562-5).

With increasing infection severity on the IDSA-IWGDF classification system, there were increasing risks of hospitalization, osteomyelitis, amputation, and other complications such as peripheral neuropathy and vascular disease. "We believe the results of this study are the first to validate these new guidelines," Dr. Lavery and his associates said. They added that a reliable infection classification system, "designed to be simple to apply and easy to remember," should help clinicians decide whether a patient should be hospitalized, whether to use parenteral or oral antibiotics, and how urgently surgery or other treatments should be performed.

"Even guidelines developed by a consensus of experts only become credible if they are validated," said Dr.George Andros when asked to comment on this article.

"The IDSA has simplified its classification of infected diabetic foot ulcers into four categories, 0 through 3, with the goal of encouraging its widespread use. Lavery and colleagues have convincingly demonstrated that the IDSA classification system effectively predicts infectious complications arising from diabetic foot ulcerations. It is hoped that these findings will result in wider application of this scoring system," he concluded. Dr Andros is editor of VASCULAR SPECIALIST, a vascular surgeon and the director of vascular services and the Diabetic Foot Center at Providence-Saint Joseph Medical Center in Burbank, Calif.