Interactive tool
Calculate the WIfI stage
Assign a grade from 0 to 3 to each of the three components. The ischaemia grade can be derived automatically from ABI, ankle pressure, toe pressure or TcPO2.
How to use it
Instructions
W — Wound
| Grade | Ulcer | Gangrene |
|---|---|---|
| 0 | No ulcer (ischaemic rest pain) | None |
| 1 | Small, shallow ulcer on the distal leg or foot; no exposed bone, unless limited to the distal phalanx | None |
| 2 | Deeper ulcer with exposed bone, joint or tendon, generally not involving the heel; shallow heel ulcer without calcaneal involvement | Limited to the digits |
| 3 | Extensive, deep ulcer of the forefoot and/or midfoot; deep, full-thickness heel ulcer with or without calcaneal involvement | Extensive, involving the forefoot and/or midfoot; full-thickness heel necrosis |
I — Ischemia
| Grade | ABI | Ankle systolic pressure | Toe pressure / TcPO2 |
|---|---|---|---|
| 0 | ≥ 0.80 | > 100 mmHg | ≥ 60 mmHg |
| 1 | 0.60 – 0.79 | 70 – 100 mmHg | 40 – 59 mmHg |
| 2 | 0.40 – 0.59 | 50 – 70 mmHg | 30 – 39 mmHg |
| 3 | ≤ 0.39 | < 50 mmHg | < 30 mmHg |
In patients with diabetes or chronic kidney disease the ABI is often falsely raised by medial calcification: in these cases the grade should be assigned from the toe pressure or TcPO2, not the ABI.
fI — foot Infection
| Grade | Definition (IDSA / IWGDF criteria) |
|---|---|
| 0 | No symptoms or signs of infection |
| 1 | Mild infection: involving only skin and subcutaneous tissue; erythema > 0.5 cm and ≤ 2 cm around the wound; at least two local signs of inflammation |
| 2 | Moderate infection: erythema > 2 cm, or involvement of structures deeper than skin and subcutaneous tissue (abscess, osteomyelitis, septic arthritis, fasciitis), without systemic signs |
| 3 | Severe infection: with a systemic inflammatory response (at least two SIRS criteria) |
Grade fI3 requires immediate control of sepsis — drainage, debridement, urgent minor amputation if needed and systemic antibiotics — before revascularisation is planned. The order of priorities is: control the infection, then restore perfusion, then reconstruct the foot.
When to restage
WIfI is a dynamic snapshot: it should be recalculated after infection control, after revascularisation and whenever the wound changes significantly. Post-procedural restaging predicts limb salvage better than the initial stage: a patient who moves from stage 4 to stage 2 after revascularisation has a radically different prognosis from one who remains in stage 4.
Clinical references
Guidelines and interpretation
Clinical stage and risk of major amputation at 1 year
| Stage | Risk (Mills 2014) | Observed 1-year major amputation (meta-analysis) |
|---|---|---|
| 1 | Very low | 0% |
| 2 | Low | 8% (95% CI 3–21%) |
| 3 | Moderate | 11% (95% CI 6–18%) |
| 4 | High | 38% (95% CI 21–58%) |
The observed rates come from the systematic review and meta-analysis by van Reijen et al. (Eur J Vasc Endovasc Surg 2019; four studies). They are population averages with wide confidence intervals: individual risk also depends on comorbidities, nutritional status, availability of autologous vein and quality of the distal run-off.
The logic of the three dimensions
The conceptual contribution of WIfI is the recognition that ischaemia alone does not determine limb prognosis. An extensive wound with deep infection can lead to amputation even with modest ischaemia; conversely, severe ischaemia without a wound or infection has a better limb prognosis than the old definition of “critical ischaemia” implied. The three components interact, and the staging system reproduces this interaction rather than adding up the grades.
WIfI and the benefit of revascularisation
Alongside the amputation-risk table, the original publication (Mills 2014, Table IV b) gives a second consensus table: the likelihood of benefit of, or requirement for, revascularisation, estimated assuming the infection can be controlled first. Rows: wound grade; columns: infection grade.
| fI0 | fI1 | fI2 | fI3 | |
|---|---|---|---|---|
| W0 | VL | VL | VL | VL |
| W1 | VL | VL | VL | VL |
| W2 | VL | VL | VL | VL |
| W3 | VL | VL | VL | VL |
| fI0 | fI1 | fI2 | fI3 | |
|---|---|---|---|---|
| W0 | VL | L | L | M |
| W1 | L | M | M | M |
| W2 | M | M | H | H |
| W3 | M | M | M | H |
| fI0 | fI1 | fI2 | fI3 | |
|---|---|---|---|---|
| W0 | L | L | M | M |
| W1 | M | H | H | H |
| W2 | H | H | H | H |
| W3 | H | H | H | H |
| fI0 | fI1 | fI2 | fI3 | |
|---|---|---|---|---|
| W0 | M | H | H | H |
| W1 | H | H | H | H |
| W2 | H | H | H | H |
| W3 | H | H | H | H |
VL = very lowL = lowM = moderateH = high
- Ischaemia grade 0: very low benefit in every combination; the problem is not perfusion.
- Ischaemia grade 1: very low to high, increasing with wound extent and infection.
- Ischaemia grade 2–3: from low (W0, I2) to high; with any wound the benefit is at least moderate.
- According to Mills, W0 patients with ischaemia grade 1–2 have no wound and no ischaemic rest pain (which requires I3) and do not require revascularisation.
Place in the guidelines
- Global Vascular Guidelines 2019 (ESVS, SVS and WFVS): WIfI is an integral part of the PLAN framework (Patient risk, Limb severity, ANatomic pattern of disease). WIfI covers the “L”; patient risk and the anatomic pattern (GLASS classification) complete the decision.
- IWGDF/ESVS/SVS 2023: the intersocietal guideline on peripheral artery disease in people with diabetes and a foot ulcer adopts WIfI in the assessment of limb threat and of the likely benefit of revascularisation.
What WIfI does not do
- It does not describe the anatomy of the arterial disease: for that you need the GLASS classification or angiographic assessment of run-off and angiosomes.
- It does not assess patient risk: comorbidities, life expectancy and functional status remain decisive in choosing between revascularisation, conservative treatment and primary amputation.
- It does not set the strategy: open or endovascular surgery is a decision that depends on the anatomy, the availability of autologous vein and operative risk.
- It does not apply (Mills 2014) to acute limb ischaemia, acute “trash foot”, ischaemia due to emboli, acute trauma or mangled extremity, pure venous ulcers, vasospastic disease, or wounds caused by non-atherosclerotic conditions (vasculitis, collagen vascular disease, Buerger’s disease, neoplasm, dermatoses, radiation).
- In acute limb ischaemia the reference system is the Rutherford classification of acute ischaemia, which drives the timing of intervention.
References
Sources
- Mills JL. et al., J Vasc Surg 2014 — The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System: risk stratification based on Wound, Ischemia, and foot Infection (WIfI). Table IV a (amputation risk) and IV b (benefit of revascularisation). doi:10.1016/j.jvs.2013.08.003
- Conte MS. et al., J Vasc Surg / Eur J Vasc Endovasc Surg 2019 — Global Vascular Guidelines on the management of chronic limb-threatening ischemia.
- van Reijen NS. et al., Eur J Vasc Endovasc Surg 2019 — The prognostic value of the WIfI classification in patients with chronic limb threatening ischaemia: a systematic review and meta-analysis.
- Cerqueira LO. et al., J Vasc Bras 2020 — WIfI classification: the Society for Vascular Surgery lower extremity threatened limb classification system, a literature review (reproduces the stage tables).
- IWGDF/ESVS/SVS 2023 — Guidelines on diagnosis, prognosis and management of peripheral artery disease in people with diabetes and a foot ulcer.
Quick-reference tool for healthcare professionals. It does not replace the original guidelines, the summaries of product characteristics or the specialist's clinical judgement. All calculations run in the browser: no patient data is transmitted to or stored on any server.