Importance of postprocedural Wound, Ischemia, and foot Infection (WIfI) restaging in predicting limb salvage

Abstract

Objective: The Wound, Ischemia, and foot Infection (WIfI) classification system was created to encompass demographic changes and expanding techniques of revascularization to perform meaningful analyses of outcomes in the treatment of the threatened limb. The WIfI index is intended to be analogous to the TNM staging system for cancer, with restaging to be done after control of infection and after revascularization. Our goal was to evaluate the effectiveness of WIfI restaging after therapy in the prediction of limb outcomes.

Methods: Preoperative WIfI scoring was performed prospectively for all critical limb ischemia patients who underwent revascularization from January 2014 to June 2015. WIfI restaging and assessment of outcomes were performed retrospectively through August 2016. WIfI classification was determined at the following intervals: preoperatively, immediately postoperatively, and 1 month and 6 months after intervention. Amputation-free survival (AFS) was the primary end point. Kaplan-Meier plot analysis and comparisons of preoperative grades with respective postoperative grades were performed using paired t-test, χ² test, and correlation analyses.

Results: A total of 180 limbs and 172 critical limb ischemia patients underwent revascularization, of which 29 limbs had major amputations (16%). Wound grades generally improved after surgery across the entire cohort. Major amputation was associated with preoperative wound grade and remained associated with wound grade at postoperative restaging at 1 month and beyond on the basis of amputation frequency analysis (preoperatively, 1 month, and 6 months, P = .03, < .001, and < .001, respectively). Wound grade was significantly associated with AFS at 1 month and 6 months after intervention (log-rank, P < .001 for restaging intervals). Ischemia grades improved initially with a slight decline across the cohort at 6 months. Ischemia grade at 1 month postoperatively was associated with AFS (log-rank, P = .03). Foot infection grades also improved at each time interval. Foot infection grade was associated with AFS at 1 month postoperatively (log-rank, P < .001) and at 6 months (log-rank, P = .017).

Conclusions: WIfI restaging is an important tool for predicting limb loss and assessing adequacy of intervention, more so than baseline WIfI alone. The 1- and 6-month postoperative ischemia grade correlated with AFS, whereas preoperative grade did not. The 1- and 6-month postoperative wound and foot infection grades additionally correlated with AFS. WIfI restaging at 1 month and 6 months postoperatively may help identify a cohort that remains at higher risk for limb loss and may merit more expeditious reintervention.