Clinical and Economic Impact of the Society for Vascular Surgery Wound, Ischemia, and Foot Infection (WIfI) Classification: Insights from the Singapore Vascular Quality Initiative.

Abstract

The Society for Vascular Surgery Wound, Ischemia, and Foot Infection (WIfI) classification is widely used for risk stratification in patients with chronic limb threatening ischaemia. However, its clinical and economic implications within an Asian healthcare setting remain unclear. This study aimed to examine the association of WIfI stages with hospital length of stay (LOS), inpatient costs, major amputation risk, and survival outcomes. This was a retrospective analysis of prospectively collected single centre data. Data were accrued from the Singapore General Hospital Vascular Quality Initiative (VQI) registry and the hospital's central billing system. Data were analysed for 1252 patients who underwent lower extremity peripheral vascular interventions (PVI) between January 2019 and December 2024. WIfI stage (1 - 4) was determined at the time of intervention. Clinical outcomes included total and postintervention LOS, complications, major amputation rates, and mortality. Total inpatient costs were assessed in 2024 US dollars. Multivariable linear regression and logistic regression were used to adjust for baseline covariates. Cox proportional hazards and Fine-Gray competing risks regression models evaluated overall survival (OS) and major amputation incidence, respectively. Higher WIfI stages correlated significantly with longer mean total and postintervention LOS, and higher inpatient hospitalisation costs ($25,547.7 in Stage 1 vs. $51,520.2 in Stage 4; p < .001). After multivariable adjustment, each WIfI stage increment was associated with an additional cost of $7637 (95% confidence interval [CI] $5733 - $9541). Stage 4 patients had significantly increased risks of major amputation (subdistribution hazard ratio [SHR] 2.50; 95% CI 1.35 - 4.63) and reduced OS (hazard ratio [HR] 1.38; 95% CI 1.12 - 1.71). WIfI classification predicts clinical outcomes and hospitalisation costs in this Asian setting. Higher WIfI stages significantly increase hospital LOS, costs, major amputation risk, and mortality, emphasising the value of the classification for clinical and economic decision making.