Congratulations to colleagues from UAB on this fascinating work. It focuses on the critical importance of re-staging using the WIFI Limb Score.
In essence, worthwhile classifications are like living, evolving organisms. They change over time– just like the people and the conditions they describe.
The wound, ischemia, and foot Infection (WifI) classification system was created to encompass demographic changes and expanding techniques of revascularization to perform meaningful analysis of outcomes in the treatment of critical limb ischemia (CLI). 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. We previously demonstrated that preoperative wound and infection grades are predictive of limb loss, whereas ischemia grade is not. Our goal was to evaluate the effectiveness of WifI restaging after therapy in the prediction of limb loss.
Preoperative WifI scoring was performed prospectively on all patients with CLI who underwent revascularization from January 2014 to June 2015. WifI restaging and assessment of outcomes was performed retrospectively using our vascular database and electronic medical records through August 2016. WifI classification was determined preoperatively, immediately postoperative, and at 1 and 6 months after intervention. Amputation-free survival was the primary end point. Kaplan-Meier plot analysis and comparisons of preoperative grades to respective postoperative grades were performed using paired t-test, χ2, and correlation analyses.
A total of 180 patients with CLI underwent revascularization, of which 29 had major amputations (16%). Wound grades generally improved following 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 based on amputation frequency analysis (preoperative, 1 month, and 6 months; P = .03, <.001, <.001, respectively). Wound grade was significantly associated with amputation-free survival at 1 and 6 months after intervention (log-rank <0.001 for restaging intervals). Ischemia grades improved initially with a slight decline across the cohort at 6 months: patients with ischemia grade 0 or 1 (ABI ≥ 0.6) were 20.6% of the cohort preoperatively, improving to 70.7%, 85.8%, and 77.6% immediately postoperative, 1 month, and 6 months, respectively. Ischemia grade at 1 month postoperative was associated with amputation-free survival (Fig 1), log-rank 0.03. Foot infection grades also improved at each time interval. The proportion of patients with no signs of infection (grade 0) were 74.4%, 85.4%, 87.0%, and 95.8% preoperatively, immediately postoperative, 1 month, and 6 months postoperative, respectively. Foot infection grade at 1 month postoperative was associated with amputation-free survival (Fig 1, log-rank, <0.001), as well as at 6 months (log-rank, 0.017).
WifI restaging is an important tool for predicting limb loss and assessing adequacy of intervention, more so than baseline WifI alone. One month postoperative ischemia grade correlated with amputation-free survival, whereas preoperative grade did not. One month postoperative wound and foot infection grades additionally correlated with amputation-free survival. WifI restaging at 1 month postoperative may help identify a cohort that remains at higher risk for limb loss and may merit reintervention.