To identify the risk factors for diabetic foot complicated by necrotizing soft tissue infection (NSTI).

Based on retrospective chart review, we presented all cases of diabetic foot infection (DFI) patients treated at Diabetic Foot Treatment & Preventive Center of Peking University First Hospital from January 2010 to December 2017. The severity of DFI was assessed for all the patients using the international working group on the diabetic foot (IWGDF) classification scheme, then the patients were divided into either an NSTI group or a non-NSTI group. Both univariate and Logistic regression analyses were performed, and receiver operating characteristic curve analysis was used to identify the cutoff values of the risk factors.

A total of 141 patients were enrolled in this study, and the rates of mild, moderate, and severe infections were 14.9%, 61.0%, and 24.1%, respectively. There were 31 patients in the NSTI group and 110 patients in the non-NSTI group. The incidence of NSTI in DFI patients was 22.0%. Univariate analysis showed that the age of patients in NSTI group was younger, the duration of diabetic foot ulcer was shorter, the infection was more severe, the major amputation rate was higher, glycosylated hemoglobin, C-reactive protein (CRP), and white cell count (WBC) were higher, and albumin and hemoglobin were lower (P＜0.05). Multivariate Logistic regression analysis showed that WBC and CRP were the risk factors for NSTI (P＜0.05), and the cutoff values were 12.00×10⁹/L and 100 mg/L, respectively.

It is not uncommon for DFI patients with NSTI. The severity of DFI should be routinely assessed according to the IWGDF guidelines. Clinicians should be alert to the possibility of NSTI for patients with severe infections or WBC≥12.00×10⁹/L or CRP≥100 mg/L.