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Real World Application of WIfI Scores in Chronic Limb Threatening Ischemia Patients
Margaret E Smith, Jeremy Albright, Matthew Corriere, Nicholas Osborne, Drew Braet, Peter Henke
University of Michigan, Ann Arbor, MI

BACKGROUND: The 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, the real-world utilization of the system and whether it is more predictive of outcomes following open revascularization or peripheral interventions is unclear. Therefore, we sought to determine the adoption of the WIfl classification system within a contemporary statewide collaborative as well as the impact of patient factors, procedural approach, 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 (OSR) or peripheral vascular intervention (PVI) between 2018 - 2021. The primary exposures were preoperative WIfI score and procedure type. Patients were categorized into risk groups by their cumulative WIfI score: 0 = very-low risk, 1-3 = low-risk, 4-6 = moderate-risk, 7-9 = high-risk. The primary outcomes were 30-day and 1-year amputation and mortality. Multivariable logistic regression was performed to estimate the association of WIfI score and procedure type on outcomes. RESULTS: In the cohort of 17,417 patients, 83.4% (n=14,529) had WIfI scores documented. PVIs were performed on 57.6% of patients, and 42.4% underwent an OSR. 36.9% were very-low risk, 34.7% low risk, 21.7% moderate risk, and 6.7% high risk. Moderate and high-risk patients had higher rates of diabetes, congestive heart failure, and renal failure, and were less likely to be current or former smokers. As risk increased from low to high, 1-year mortality increased from 12% to 21%, 30-day amputation rates increased from 9% to 43%, and 1-year amputation rates increased from 21% to 61%.

Short and Long Term Outcomes Following Revascularization by WIfI Score
WIfI Score
01-34-67-9p-value
30-Day Mortality2.8%3.2%4.0%5.9%<0.001
1-Year Mortality11.0%12.3%16.7%20.9%<0.001
30-Day Amputation3.9%9.2%27.2%43.4%<0.001
1-Year Amputation12.1%21.6%41.9%61.3%<0.001
50% of high-risk patients underwent OSR while very-low risk patients were most likely to have received a PVI (66%). As patient risk increased, the likelihood of 30-day amputation after PVI increased more significantly than for patients undergoing OSR. 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 amputate rates.
. CONCLUSIONS: In a large statewide collaborative, increasing WIfI scores correlate with worse short- and long-term outcomes. While high-risk patients are most likely to undergo OSR, the risk of amputation increases significantly more in the PVI group as the WIfI score increases, suggesting high-risk patients may be better be served with OSR. Given the difference in outcomes among patients screened with the WIfI classification, compared to those without, application of the WIfI system may not only risk stratify patients but may also lead to improved procedural selection.

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