Since each of the three categories (wound, ischemia, and foot infection) has four grades of severity, the system produces a grid with 64 theoretically possible clinical combinations (WIfI classes).

The 64 theoretical WIfI patient combinations were classified into four groups based on projected benefit from anatomic revascularization - from no (or very low) benefit to greatest potential benefit:

• Clinical stage 1 - Very Low
• Clinical stage 2 - Low
• Clinical stage 3 - Moderate
• Clinical stage 4 - High