SVS StandardWIfI Threatened Limb Classification
Wound (W)Depth & size of non-healing foot ulcers or gangrene
Ischemia (I)Perfusion level measured via ABI or toe pressure
foot Infection (fI)Infection clinical severity
Risk Prediction
Select the parameters for Wound, Ischemia, and foot Infection to estimate the 1-year major amputation probability.
Guidelines & Evidence
Verified
Last Review: 2026
When to Use
What is the WIfI Classification?
The WIfI (Wound, Ischemia, foot Infection) classification is a staging system for chronic limb-threatening ischemia (CLTI) developed by the Society for Vascular Surgery (SVS) in 2014. Unlike traditional Rutherford and Fontaine classifications (which combine rest pain, ulceration, and gangrene into single categories without differentiating severity), WIfI separately grades three components: Wound (0-3), Ischemia (0-3), and foot Infection (0-3). The composite stage (I-IV) predicts 1-year amputation risk and guides the urgency and type of revascularization. WIfI is recommended by the SVS and Global Vascular Guidelines for all patients with CLTI (rest pain, ulceration, or gangrene due to PAD).
Primary Clinical Indications
Risk stratification in CLTI – Predicts 1-year major amputation risk and guides treatment intensity (medical therapy, endovascular revascularization, surgical bypass, or primary amputation)
Determining revascularization urgency – Higher WIfI stages (III-IV) with severe infection (Infection grade 3) require urgent (days) revascularization or primary amputation to prevent sepsis and limb loss
Predicting wound healing potential – Combinations of ischemia and wound grades predict likelihood of healing with conservative care vs need for revascularization
Clinical trial enrollment and stratification – Many CLTI trials (BEST-CLI, BASIL-2, PROMISE) use WIfI for inclusion criteria and outcome adjustment
Comparing outcomes across institutions – Standardized reporting allows benchmarking of limb salvage rates for CLTI patients
Decision support for primary amputation – Patients with WIfI stage IV (high wound grade, severe ischemia, severe infection) may have very low likelihood of limb salvage, and primary amputation may be more appropriate than attempted revascularization
Communication between providers – Standardized language ("WIfI stage III, predicted 1-year amputation risk 40%") for referring patients to vascular surgery
Contraindications / Limitations
Not applicable to patients without CLTI – WIfI is designed for patients with rest pain (Rutherford 4), ulceration (Rutherford 5), or gangrene (Rutherford 6). Do not use for asymptomatic PAD or claudication only (Rutherford 0-3).
Does not account for patient comorbidities – WIfI predicts limb outcomes but not patient survival; a patient with severe frailty, dementia, or advanced cancer may not benefit from revascularization regardless of WIfI stage.
Inter-observer variability in wound and infection grading – Wound depth, presence of osteomyelitis, and infection extent can be subjective; requires standardized assessment (probe-to-bone, MRI for osteomyelitis).
Ischemia grading requires objective testing (ABI, TBI, toe pressure) – May not be available in all settings (e.g., resource-limited, primary care).
Does not include rest pain as a separate category – WIfI focuses on tissue loss and infection; patients with rest pain but no tissue loss (Rutherford 4) automatically have wound grade 0; their amputation risk is determined by ischemia grade and infection (grade 0).
Not validated for acute limb ischemia – WIfI is for chronic CLTI (symptoms >2-4 weeks). Acute limb ischemia (sudden onset, <14 days) requires separate classification (Rutherford acute categories).
Complexity – More complex than traditional Rutherford/Fontaine staging; requires training to apply correctly.
Still evolving – Ongoing validation studies may refine thresholds or add components (e.g., pedal arch patency, frailty).
WIfI vs Rutherford vs Fontaine for CLTI
| Feature | WIfI (SVS 2014) | Rutherford (1997) | Fontaine (1950s) |
|---|---|---|---|
| Components | Wound (0-3), Ischemia (0-3), Infection (0-3) | Single stage (4-6) combining rest pain, ulcer, gangrene | Stage III (rest pain), Stage IV (ulcer/gangrene) |
| Granularity | High (separate scores for each component) | Low (limited differentiation) | Very low (only two categories for CLTI) |
| Predicts amputation risk | Yes (validated, 1-year major amputation risk by stage) | Limited (Rutherford 6 has higher risk than 4, but not quantified) | No |
| Guides revascularization | Yes (higher stages more urgent, more likely to require bypass than endovascular) | Limited (no guidance on type or timing) | No |
| Used in clinical trials | Yes (BEST-CLI, BASIL-2, PROMISE) | Yes (historical trials) | Yes (historical) |
| Recommended by SVS/ESVS | Yes (2019 Global Vascular Guidelines) | Yes (but less detailed) | Yes (but less detailed) |
| Complexity | Moderate (requires training and objective testing) | Low (simple history and physical) | Low (simple) |
Last Comprehensive Review: 2026