Real World Application of WIfI Scores in Peripheral Arterial Disease Patients

OBJECTIVE The Society for Vascular Surgery wound, ischemia, and foot infection (WIfI) classification system aims to risk stratify patients with chronic limb threatening ischemia (CLTI), predicting both amputation rates and the need for revascularization. However, real-world utilization of the system and whether it accurately predicts outcomes following open revascularization and peripheral interventions is unclear. Therefore, we sought to determine the adoption of the WIfI classification system within a contemporary statewide collaborative as well as the impact of patient factor, and WIfI risk assessment on short- and long-term outcomes. METHODS Using data from a large statewide collaborative, we identified patients with CLTI undergoing open surgical revascularization or peripheral vascular intervention (PVI) between 2016 - 2022. The primary exposure was preoperative clinical WIfI stage. Patients were categorized according to the SVS Lower Extremity Threatened Limb Classification System into clinical WIfI stages1, 2, 3, or 4. The primary outcomes were 30-day and 1-year amputation and mortality. Multivariable logistic regression was performed to estimate the association of WIfI stage on post-revascularization outcomes. RESULTS In the cohort of 17,417 patients, 83.4% (n=14,529) had WIfI stage documented. Peripheral vascular interventions (PVIs) were performed on 57.6% of patients, and 42.4% underwent an open surgical revascularization (OSR). 49.5% of patients were classified as stage 1, 19.3% stage 2, 12.8% stage 3 and 18.3% of patients met stage 4 criteria. Stage 3 and 4 patients had higher rates of diabetes, congestive heart failure, and renal failure, and were less likely to be current or former smokers. One-half of stage 3 patients underwent OSR, while stage 1 patients were most likely to have received a PVI (64%). As WIfI stage increased from 1 to 4, 1-year mortality increased from 12% to 21% (p<0.001), 30-day amputation rates increased from 5% to 38% (p<0.001), and 1-year amputation rates increased from 15% to 55% (p<0.001). Finally, patients who did not have WIfI scores classified had significantly higher 30-day and 1-year mortality, as well as higher 30-day and 1-year amputation rates. CONCLUSION The Society for Vascular Surgery WIfI clinical stage is significantly associated with 1-year amputation rates in patients with CLTI following lower extremity revascularization. As nearly 55% of stage 4 patients require a major amputation within one year of intervention, this study supports use of the WIfI classification system in clinical decision making for patients with CLTI.