Survival and associated risk factors in patients with diabetes and amputations caused by infectious foot gangrene.

Background: Infectious gangrene of the foot is a serious complication of diabetes that usually leads to a certain level of lower-extremity amputation (LEA). Nevertheless, the long-term survival and factors associated with mortality in such patients have yet to be elucidated.

Methods: A total of 157 patients with type 2 diabetes who received treatment for infectious foot gangrene at a major diabetic foot center in Taiwan from 2002 to 2009 were enrolled, of whom 90 had major LEAs (above the ankle) and 67 had minor LEAs (below the ankle). Clinical data during treatment were used for the analysis of survival and LEA, and survival was tracked after treatment until December 2012.

Results: Of the 157 patients, 109 died, with a median survival time of 3.12 years and 5-year survival rate of 40%. Age [hazard ratio 1.04 (95% confidence interval 1.01-1.06)], and major LEA [1.80 (1.05-3.09)] were independent factors associated with mortality. Patients with minor LEAs had a better median survival than those with major LEAs (5.5 and 1.9 years, respectively, P  < 0.01). An abnormal ankle-brachial index was an independent risk factor [odds ratio 3.12 (95% CI 1.18-8.24)] for a poor outcome (major LEA) after adjusting for age, smoking status, hypertension, major adverse cardiac events, and renal function.

Conclusions: Efforts to limit amputations below the ankle resulted in better survival of patients with infectious foot gangrene. An abnormal ankle-brachial index may guide physicians to make appropriate decisions with regards to the amputation level.