Validation of the WIfI classification in the Vascular Quality Initiative database

The Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification was introduced in 2014 and has been validated in multiple institutional series as a useful tool to assess the severity of chronic limb-threatening ischemia (CLTI) and predict the risk of major amputation after lower extremity revascularization (LER). The Vascular Quality Initiative (VQI) Peripheral Vascular Interventions (PVI) database captures data on wounds, ischemia, and infection, which are key components of the WIfI score, but does not provide the complete WIfI stage. The aim of this study is to validate the WIfI classification in the VQI PVI database and analyze the different combinations of components.

The VQI PVI data files (2013-2024) were reviewed for patients with CLTI with available data from which to derive WIfI scores. The characteristics of patients who underwent major amputation during follow-up were compared with those who did not. Kaplan-Meier curves were compared for major amputation, reintervention, and mortality for the various WIfI stages. Cox regression analysis was performed to assess for independent risk factors associated with major amputation.

A total of 280,706 individuals underwent PVI procedures, and 130,575 presented with CLTI. WIfI stage derivation was possible for 33% (n = 42,858) of patients, 28,727 of whom had long-term follow up and were included in this study. A total of 3271 patients (11.4%) underwent major amputation after LER. Patients requiring amputation were significantly younger and more likely to be male, Hispanic, or African American compared with patients who did not undergo amputation. Patients in the amputation group were more likely to be affected by most risk factors and presented with higher WIfI stages. On Kaplan-Meier analysis, the estimates of 1-year major amputation or mortality significantly increased with each WIfI stage (stage 1, 7.7%; stage 2, 8.2%; stage 3, 14.7%; stage 4, 20.2%; P < .001). Cox regression analyses demonstrated that WIfI clinical stage (stage 2 vs 1, hazard ratio [HR], 1.17; 95% confidence interval [CI], 1.06-1.27; stage 3 vs 1, HR, 1.41; 95% CI, 1.31-1.54; stage 4 vs 1, HR, 1.69; 95% CI, 1.54-1.82) and end-stage renal disease (HR, 1.96; 95% CI, 1.8-2.14) were independently associated with major amputation or mortality.

In conclusion, this study validated the WIfI classification in the VQI PVI database, confirming its value in predicting major amputation and mortality in patients with CLTI. Higher WIfI stages were independently associated with increased risk of major amputation and mortality, highlighting the importance of capturing and integrating the WIfI score into all VQI modules related to treatment of peripheral artery disease.