Spotlight on the diabetic foot

Recent diabetes research analyzed trends in lower-extremity amputations in Ontario, Canada, as well as how health literacy, procalcitonin, and mortality risk relate to diabetic foot infection outcomes.

Several recent studies looked at lower-extremity complications of diabetes, including infections and amputations.

One study, published in the Sept. 3 CMAJ, tallied amputations in Ontario between 2005 and 2016. A total of 20,062 patients in the province underwent lower-extremity amputation during the time period, 81.8% of whom had diabetes and 93.8% of whom had peripheral artery disease; 75.6% had both diseases. The rate of these amputations per 100,000 in the general population was 9.88 in the second quarter of 2005, 8.62 in the fourth quarter of 2010, and 10.0 in the first quarter of 2016. Rates of major amputation did not increase, indicating that the recent growth was driven by minor amputations, the authors said. They noted that these results differ from the declines seen in other cardiovascular complications of diabetes and “support renewed efforts to prevent and decrease the burden of limb loss.” An accompanying editorial noted that recent U.S. data have shown reversals in previously improving rates of diabetes complications and called on clinicians to “renew their efforts in organizing clinical processes for identifying at-risk feet and facilitating preventive measures.”

Another study, published in the September issue of The Journal of Foot & Ankle Surgery, analyzed health literacy among patients of one large U.S. orthopedic practice. It found a statistically significant difference in health literacy between patients who had a diabetic foot amputation or reamputation in the previous two years (n=177) and the practice's general patient population (n=14,683). Patients in the former group were more than eight times as likely to have inadequate health literacy as those in the latter. “Targeted patient education interventions and outreach that aim to address known health literacy barriers will likely have potential to reduce amputations that result from poor diabetes self-management and care,” the authors said.

Two other studies looked at patients hospitalized with diabetic foot infections. One, published by the Journal of Diabetes Research on Aug. 14, found procalcitonin to be a useful prognostic marker. Of 86 Italian patients with diabetic foot infection and critical limb ischemia, 23 had positive procalcitonin values, and these patients had worse outcomes on limb salvage (30.4% vs. 93.6%, P=0.0001), major amputation (13% vs. 6.3%, P=0.3), and hospital mortality (56.5% vs. 0%, P<0.0001). Other inflammatory markers were not predictors of these outcomes, nor was the severity of infection, leading the study authors to conclude that procalcitonin could help to identify high-risk patients without other indications of poor outcomes.

Another Italian study, published by Acta Diabetologica on Aug. 29, analyzed mortality among 5,999 patients first hospitalized with diabetic foot in 2012 to 2016. During a mean follow-up of 2.5 years, it found mortality rates of 16% in patients without amputation, 18% in those with major amputation, and 30% in those with minor amputation. Mortality risk was also elevated with male sex, insulin treatment, more severe diabetes complications (particularly need for dialysis), and lower educational levels. The results highlight the underappreciated burden of diabetic foot hospitalizations not associated with amputation, the authors said.