The target population for this system includes any patient with:

• Ischemic rest pain, typically in the forefoot with confirmatory, objective hemodynamic studies (ABI <0.40, Ankle Pressure (AP) <50 mmHg, Toe Pressure (TP) <30, TcPO₂ <20 mmHg)
• A diabetic foot ulcer
• Nonhealing lower limb or foot ulceration of at least 2 weeks duration
• Gangrene involving any portion of the foot or lower limb

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 12-member group was instructed to use the classification system to address two questions:

1. What is the perceived risk of amputation for each possible combination?
2. What is the perceived benefit from revascularization for each possible combination?