How is PASI calculated?

PASI = 0.1×(Ah×Eh) + 0.2×(Aa×Ea) + 0.3×(At×Et) + 0.4×(Al×El). Each body area (head/neck, upper limbs, trunk, lower limbs) has area score (0–6) and severity scores (erythema, induration, desquamation: 0–4 each). Range 0–72.

What PASI scores define mild, moderate, and severe psoriasis?

PASI 20: severe. PASI 75 response (≥75% improvement) is the standard regulatory endpoint for biologic approvals. PASI 90 and PASI 100 (clear skin) are increasingly used.

PASI Psoriasis Area Severity Index

Calculate the Psoriasis Area and Severity Index (PASI) — the gold standard for assessing psoriasis severity — by scoring erythema, induration, and scaling across four body regions weighted by area.

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Frequently Asked Questions

How is PASI calculated?

What PASI scores define mild, moderate, and severe psoriasis?