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Introduction: Our aim was to evaluate the effectiveness of the Society for Vascular Surgery WIfI classification system (Wound extent, Ischemia, foot Infection) in predicting amputation rate, time to wound healing and overall survival in patients with critical limb ischemia (CLI).
Methods: This study was a single-institution, retrospective analysis of patients presenting with critical limb ischemia (CLI) who underwent lower extremity revascularization from January 2012 to July 2015. All patients with CLI were assigned a WIfI score based on the wound status, ischemia and foot infection at the time of their initial presentation for revascularization. Demographics, time to wound healing, rate of amputation and number of subsequent interventions were included for analysis.
Results: Between January 2012 and July 2015, 284 patients underwent lower extremity revascularization (116 endovascular, 50 open, 2 hybrid). 98 patients were excluded as they did not have CLI (defined as rest pain or tissue loss) and an additional 4 did not have sufficient documentation to determine a pre-operative WIfI score leaving 182 evaluated in our cohort. Patients were stratified based on WIfI scores and risk of amputation. 9 (5%) patients were classified as Very Low (VL), 62 (34%) as Low (L), 32 (17.5%) as Medium (M), and 79 (43.5%) as High (H) risk. Multivariant analysis demonstrated similar demographics between the groups. Of the 182 CLI patients evaluated, 33 (18%) patients required amputation either above or below knee. Logistical regression demonstrated a statistically significant higher risk of major amputation between the L (4.8%) and H risk (29.1%) categories (p < 0.0001) but this difference was not seen between the other groups. This is likely due to the small cohort of patients who were categorized as very low risk. One hundred and forty patients presented with tissue loss prior to revascularization. Of these, 119 (85%) experience wound healing during follow up. A significant correlation between WIfI score and wound healing (p < 0.0001) was seen, however, there was no statistical significance when comparing VL, L, M and H groups. When analyzing WIfI categories and number of subsequent interventions, we found that 22% of VL risk, 46.7% of L risk, 62% of M risk, and 24% of H risk patients required additional revascularization. Though a trend can be seen between groups, the results were not statistically significant.
Conclusion: Our results are consistent with previous reports that SVS WIfI scores correlate with rates of major amputation. However, statistical significance between WIfI groups was only found when comparing the L risk to the H risk categories. This is likely due to the small sample size, as only nine patients were classified as very low risk. Time to wound healing did correlate with WIfI scores, however, no statistical significance was seen when analyzing between the risk classifications. While trends exist between WIfI scoring and rates of major amputation or wound healing, additional multi-instituional studies are needed in order to obtain a sample size large enough to fully validate the anticipated outcomes previously predicted by the SVS expert panel