Prognostic value of Wound, Ischemia, and foot Infection classification score in patients on chronic hemodialysis undergoing lower extremity bypass surgery for critical limb ischemia

Objective: Although lower extremity bypass surgery is frequently performed to treat peripheral artery disease, poor prognoses among patients on hemodialysis (HD) remain a major concern. Wound, Ischemia, and foot Infection (WIfI) classification is widely used to predict amputation risk; however, the efficacy of this system in this population remains unclear. This study aimed to evaluate the characteristics of the WIfI score and its prognostic value in patients with critical limb ischemia on HD. Methods: This retrospective study used the WIfI classification to assess preprocedural threatened limb grades of 361 consecutive patients (224 on HD, 137 not). The primary end points were major amputation and/or all-cause mortality, and patients were followed for 5 years. Results: High-risk WIfI classifications were more prevalent among patients on HD than among those not (18.8%, 24.1%, and 57.1% vs 51.1%, 15.3%, and 33.6% at low, moderate, and high risk, respectively). Although an ischemia grade of ≥2 was comparable between patients on HD and those not (97.8% vs 99.2%; P = .74), wound and infection grades of ≥2 were more prevalent among patients on HD than those not (56.7% vs 32.8% [P < .0001] and 53.1% vs 30.7% [P < .0001], respectively). The cumulative incidence rates of amputation and/or mortality at 5 years were 26.0%, 54.6%, and 61.9% in low-, moderate-, and high-risk patients, respectively; 27.4%, 53.5%, 55.6%, and 67.3% for wound grades 0, 1, 2, and 3, respectively; and 42.2%, 43.0%, 54.3%, and 80.6% for infection grades 0, 1, 2, and 3, respectively. WIfI classification (adjusted hazard ratio [aHR]. 2.73; 95% confidence interval [CI], 1.34-5.57 [P = .0059] for high risk vs low risk), wound grade (aHR, 3.67; 95% CI, 1.67-8.31 [P = .0009] for grade 3 vs 0), and infection grade (aHR, 2.71; 95% CI, 1.35-5.32 [P = .0052] for grade 3 vs 0) were identified as independent predictors for amputation and/or mortality. Among patients without wounds, those on HD had poorer prognoses than those not (0% among those not on HD; P < .0001), as did patients without infection (4.7% among those not on HD; P = .0005). Conclusions: WIfI classification, wound grade, and infection grade stratified the risk of amputation and/or mortality after bypass surgery. The wound and infection grades were higher among patients on HD than those not; however, a higher risk of a poor prognosis should always be considered in this population, even without any wound or infection.