Study: Infection Dramatically Raises Risk Of Amputation, Hospitalization

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By Brian McCurdy, Senior Editor

   It is no secret that foot infections can lead to a range of complications up to and including lower extremity amputation. However, a recent study has demonstrated a dramatically higher risk of both amputation and hospitalization in diabetes patients who develop foot infections as opposed to those without infection. The authors say this is the first prospective study to report the incidence of foot infections in a defined population as well as the risk factors for infection.

   The study, published in a recent issue of Diabetes Care, found that patients with diabetes and a foot infection had a 154.5 times greater risk of amputation and are 55.7 times more at risk for hospitalization than those without infection.

   The authors of the study tracked 1,666 patients with diabetes over two years and discovered that 151 patients (9.1 percent) developed 199 foot infections. Although most patients had infections that involved just the soft tissue, the study notes that approximately 20 percent of infected patients had osteomyelitis that was proven by bone cultures. In addition, the researchers discovered that foot wounds preceded all but one infection. Among the significant independent risk factors for foot infection were wounds that penetrated to bone, wounds present for over 30 days, recurrent wounds, wounds with a traumatic etiology and peripheral vascular disease.

How can DPMs prevent infection and accordingly lower the risk for amputation?

   Lawrence Lavery, DPM, a co-author of the study, emphasizes aggressive wound healing, noting that infection and amputation are not common unless the patient has a wound or portal through which bacteria can invade the foot. However, Dr. Lavery notes that many effective methods of facilitating wound healing, including total contact casts (TCCs) and instant TCCs, are “not attractive” to patients.

    “Perhaps if they understood the risk of losing their leg, they would be more willing to undergo this type of therapy,” adds Dr. Lavery, an Associate Professor in the Department of Surgery at Texas A&M Health Science Center College of Medicine.

   The best methods of preventing infection are those that help patients avoid foot wounds, says study co-author Benjamin Lipsky, MD. Citing a 2005 article he co-authored in the Journal of the American Medical Association, Dr. Lipsky >says such methods include screening for loss of protective sensation, assessment of foot biomechanics and screening for peripheral vascular insufficiency. He notes that screening for these factors can help stratify patients into groups by their risk for developing an ulcer. Ensuring periodic foot examinations and debriding calluses can also prevent foot ulcers, according to Dr. Lipsky, a Professor of Medicine at the University of Washington School of Medicine.

   In addition to educating patients on proper foot care, Dr. Lipsky says clinicians should encourage these patients to optimize their glycemic control, stop smoking, wear appropriate footwear and practice proper principles of foot hygiene.

Emphasizing Timely And Appropriate Antibiotic Usage

   If a patient does develop a wound, Dr. Lipsky says the clinician should quickly assess whether the patient has an infection. If so, the clinician should obtain proper culture specimens and choose an appropriate antibiotic regimen based on published guidelines.

    “Quick and proper care of infections can usually prevent amputations, especially major ones,” asserts Dr. Lipsky.

   Does prophylactic antibiotic therapy have a role for patients with diabetes at high risk for foot infection? Dr. Lavery notes DPMs have to balance the notion of preventing infection and avoiding the promotion of resistant organisms via the inappropriate overprescribing of antibiotics. Since there is little evidence of benefit from treating clinically uninfected wounds, he encourages judicious antibiotic selection.

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