Diabetic Foot Infections Fall — Not!

WASHINGTON — The incidence of diabetic foot infections in the U.S. appears to have dropped by half in a 15-year period, but the numbers don’t tell the whole story, a researcher said here.
In 1996, diabetic foot infections were observed in every 2.3 of 100 diabetes-related discharges from hospitals in the U.S., compared with 1.1 per 100 discharges in 2010, said Bryson Duhon, PharmD, clinical assistant professor of pharmacy at the University of Texas at Austin.
The percentage of patients who had lower limb amputation dropped from 35% of diabetic limb infections in 1996 discharges to 21.6% in 2010, he said at his poster presentation at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
But Duhon told MedPage Today that the reduction in percentage of diabetic foot infections was mainly driven by changes in the definition of diabetes, including one in 1997 that dropped the criteria for diabetes from fasting blood glucose of 140 mg/dL to 126 mg/dL or higher — a change that increased the number of diabetics by millions. Other changes in the definition also resulted in more individuals being diagnosed as diabetic.
Duhon said the definition changes resulted in patients with less severe diabetes swelling the numbers of individuals with a diabetes diagnosis — in turn, driving down the percentage of patients with diabetes-related foot infections, a late stage complication of diabetes.
“Although encouraging, the primary decrease in incidence was likely a result in newly diagnosed diabetes,” he explained. “With less stringent criteria for the diagnosis of diabetes over the years, more patients are diagnosed with new and less severe diabetes as in the past. Thus these patients are less likely to experience the severe complications of diabetes such as diabetic foot infections.”
He said that the absolute numbers of diabetic foot infections has remained fairly constant since 1996, and medical professionals “definitely should not relax their surveillance of diabetes patients because of what seems to be decreasing percentages.
“You are getting the same number of foot infections — but you are getting more diabetes diagnoses,” Duhon said. “So, to be honest, there really isn’t a reduction in these infections. We aren’t doing a better drop of preventing these infections or treating them.”
He and his colleagues interrogated the National Hospital Discharge Survey and identified 1,059,552 discharges with codes indicating diabetic foot infections between 1996 and 2010. All-cause, in-hospital mortality was 1.1% and patients were hospitalized a mean of 5 days, Duhon reported.
The researchers determined that the greatest risk for diabetic foot infections in the hospitalized patients with diabetes was peripheral vascular disease, which had an odds ratio of 2.89 (95% CI 2.87-2.91), peripheral neuropathy (OR 2.62, 95% CI 2.60-2.64), and male sex (OR 1.67, 95% CI 1.66-1.68).
In commenting on the poster presentation, Eric Senneville, MD, professor of infectious diseases at University Hospital Lille, France, told MedPage Today, “The findings in this study are consistent to what we are seeing in our clinical practice, [but] we don’t have data as precise as in this study.”

Primary source: Interscience Conference on Antimicrobial Agent and Chemotherapy
Source reference: Duhon B, et al “Declining incidence of diabetic foot infections among hospitalized adults in the U.S. from 1996 to 2010” ICAAC 2014; Abstract L-414.

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