Evaluation of revascularization benefit quartiles using the Wound, Ischemia, and foot Infection classification system for diabetic patients with chronic limb-threatening ischemia

Abstract

Objective: The Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system was developed to stratify the risk of 1-year major amputation. Recently, the WIfI scores were used to define the estimated revascularization benefit quartiles ranging from high benefit (Q1) to questionable benefit (Q4). The aim of our study was to evaluate the revascularization benefit quartiles in a cohort of diabetic patients presenting with chronic limb-threatening ischemia (CLTI).

Methods: All diabetic patients presenting to our multidisciplinary diabetic foot and wound clinic (June 2012 to May 2020) who underwent lower extremity revascularization for CLTI were included. The affected limbs were graded using the WIfI system and assigned to an estimated benefit of revascularization quartile as previously published. One-year major amputation, complete foot healing, secondary patency, and amputation-free survival were calculated among the quartiles using Kaplan-Meier curve analyses and compared using Cox proportional hazards models.

Results: Overall, 136 diabetic patients underwent revascularization of 187 limbs (mean age, 64.9 ± 11.2 years; 63.2% male; 58.8% black). The limbs were revascularized using an endovascular approach for 66.8% and open surgery for 33.2%. Of the 187 limbs, 27.3% had a high estimated benefit of revascularization (Q1), 31.6% had a moderate estimate benefit of revascularization (Q2), 20.3% had a low estimated benefit of revascularization (Q3), and 20.9% had a questionable benefit of revascularization (Q4). The estimated 1-year major amputation rates were 7.2% ± 4.1% for Q1, 3.8% ± 2.6% for Q2, 7.0% ± 4.8% for Q3, and 25.7% ± 7.5% for Q4 (P = .006). The estimated 1-year foot healing rates were 87.3% ± 5.7% for Q1, 84.8% ± 5.6% for Q2, 83.8% ± 7.4% for Q3, and 68.2% ± 9.1% for Q4 (P = .06). The overall secondary patency (P = .23) and amputation-free survival (P = .33) did not significantly differ among the groups. Using Cox proportional hazard modeling, the Q4 group had a significantly greater risk of major amputation compared with Q1 (hazard ratio, 4.26; 95% confidence interval, 1.15-15.70). Of the 14 limbs requiring major amputation, 9 (56.3%) had a patent revascularization at the time of amputation, including one of three limbs in Q1, two of two limbs in Q2, no limb in Q3, and six of nine limbs in Q4.

Conclusions: The questionable estimated revascularization benefit quartile using the WIfI classification system is significantly associated with 1-year major amputation in diabetic patients presenting with CLTI. Limbs with a questionable benefit of revascularization (Q4) will frequently require major amputation despite a patent revascularization, suggesting that the wound size and infection burden are the driving factors behind the elevated risk of major amputation in this group. Our findings support the previously described use of the WIfI classification system to predict revascularization benefit among diabetic patients with CLTI.

Keywords: Chronic limb-threatening ischemia; Diabetic foot ulcer; Revascularization benefit; WIfI.

Fig.

Kaplan-Meier curves showing major amputation (A), complete foot healing (B), secondary patency (C), and amputation-free survival (D) for diabetic patients who underwent lower extremity revascularization stratified by quartiles (Q) of estimated benefit of revascularization. All standard errors were <10%.