Work out psoriasis area severity index instantly with clear inputs, formula shown and shareable results.
Weights the four regional psoriasis subscores by their share of body surface area — 10 percent head, 20 percent arms, 30 percent trunk and 40 percent legs.
PASI
PASI = 0.1 x head subscore + 0.2 x upper limb + 0.3 x trunk + 0.4 x lower limb, where each subscore = (erythema + induration + scaling) x area grade 0-6. Range 0-72
Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
A 75 percent reduction from the baseline PASI, the classic primary endpoint in psoriasis trials.
PASI above 10, often combined with a Dermatology Life Quality Index above 10, defines moderate to severe disease for systemic therapy.