Psoriasis Area and Severity Index (PASI)
Psoriasis extent and severity (0–72).
Inputs
CompleteHead and neck: area involved
Head and neck: erythema (0–4)
Head and neck: induration (0–4)
Head and neck: scaling (0–4)
Arms: area involved
Arms: erythema (0–4)
Arms: induration (0–4)
Arms: scaling (0–4)
Trunk: area involved
Trunk: erythema (0–4)
Trunk: induration (0–4)
Trunk: scaling (0–4)
Legs: area involved
Legs: erythema (0–4)
Legs: induration (0–4)
Legs: scaling (0–4)
Worked calculation
Your values are highlighted.
- Regions
head 0.0, arms 0.0, trunk 0.0, legs 0.0= 0.0
When to use
- Moderate to severe psoriasis and response to systemic therapy.
Pearls and pitfalls
- Above 10 is often considered moderate to severe; PASI 75/90/100 are percentage improvements from baseline.
- Area score: 0 none, 1 under 10%, 2 10–29%, 3 30–49%, 4 50–69%, 5 70–89%, 6 90–100%.
Why use
The trial standard for psoriasis.
Σ region weight × (erythema + induration + scaling) × area score; weights head 0.1, arms 0.2, trunk 0.3, legs 0.4