Risk factors for foot infections in individuals with diabetes

OBJECTIVE - To prospectively determine risk factors for foot infection in a cohort of people with diabetes. RESEARCH DESIGN AND METHODS - We evaluated then followed 1,666 consecutive diabetic patients enrolled in a managed care-based outpatient clinic in a 2-year longitudinal outcomes study. At enrollment, patients underwent a standardized general medical examination and detailed foot assessment and were educated about proper foot care. They were then rescreened at scheduled intervals and also seen promptly if they developed any foot problem. RESULTS - During the evaluation period, 151 (9.1%) patients developed 199 foot infections, all but one involving a wound or penetrating injury. Most patients had infections involving only the soft tissue, but 19.9% had bone culture-proven osteomyelitis. For those who developed a foot infection, compared with those who did not, the risk of hospitalization was 55.7 times greater (95% CI 30.3-102.2; P < 0.001) and the risk of amputation was 154.5 times greater (58.5-468.5; P < 0.001). Foot wounds preceded all but one infection. Significant (P < 0.05) independent risk factors for foot infection from a multivariate analysis included wounds that penetrated to bone (odds ratio 6.7), wounds with a duration > 30 days (4.7), recurrent wounds (2.4), wounds with a traumatic etiology (2.4), and presence of peripheral vascular disease (1.9). CONCLUSIONS - Foot infections occur relatively frequently in individuals with diabetes, almost always follow trauma, and dramatically increase the risk of hospitalization and amputation. Efforts to prevent infections should be targeted at people with traumatic foot wounds, especially those that are chronic, deep, recurrent, or associated with peripheral vascular disease.