Diabetic lower extremity infection: influence of physical, psychological, and social factors

Although literature is scarce, it is a common belief that patients with lower social background are more prone to diabetic complications. The purpose of this study was to identify local, systemic, and psychosocial risk factors that can lead to severe foot infections and subsequent amputations. This study was set up as a case-control study. We enrolled 112 persons with diabetes, in an approximately 1:1 case to control ratio. Cases were defined as patients admitted to the hospital with a severe foot infection, possibly necessitating a lower extremity amputation; controls were patients admitted for nonemergent medical or surgical cause. Study participants received a physical examination and interview to evaluate exposure variables, including demographic data, general medical, surgical, diabetes, and diabetes-related complication history. Socioeconomic status was quantified with the Duncan socioeconomic impact and Siegel prestige score. The patient's knowledge of foot care was evaluated as well. The risks for severe foot infection of social, economical, and physical risk factors were compared in a stepwise logistic regression analysis. The following variables were significant factors for severe foot infection: history of previous amputation [odds ratio (OR)=19.9, P=.01], peripheral vascular disease (OR=5.5, P=.007), and peripheral neuropathy, as measured with vibratory perception threshold (OR 3.4, P=.044). Social and economic factors were not significant in this model. These data suggest that physical risk factors are important in foot infection and that the additional risk of socioeconomic status or knowledge of foot care is limited in this population.