Predictive Model for Mortality Risk Including the Wound, Ischemia, Foot Infection Classification in Patients Undergoing Revascularization for Critical Limb Ischemia

Abstract

Background: The aim of this study was to develop a predictive model for mortality risk based on preoperative risk factors, including the Wound, Ischemia, Foot Infection (WIfI) classification, in patients undergoing revascularization for critical limb ischemia. Methods: We analyzed a database of the Surgical reconstruction versus Peripheral Intervention in Patients With Critical Limb Ischemia registry, a multicenter, prospective, observational study that included 520 critical limb ischemia patients (192 surgical and 328 endovascular patients). Results: Multivariate Cox regression analysis identified old age, impaired mobility, low body mass index, renal failure, heart failure, and high WIfI grade as independent risk factors for all-cause mortality (all P <0.05). The risk score comprising these risk factors discriminated the mortality risk well; the 2-year survival rate was >90% in the first quantile of the risk score and ≈20% in the fifth quantile. The area under the time-dependent receiver operating characteristics curve was 0.829 for thirty-day mortality and 0.811 for 2-year mortality. Adding more detailed preoperative information to the predictive model revealed that cystatin C-based estimated glomerular filtration rate, left ventricular ejection fraction, and cholinesterase levels were additional independent risk factors, but the predictive accuracy of the model was not significantly improved, according to the time-dependent receiver operating characteristics curve and net reclassification improvement. Conclusions: The current study developed a risk score for mortality using preoperative risk factors, including the WIfI classification, in critical limb ischemia patients undergoing revascularization.