Psoriasis Area and Severity Index
Dermatology
Also known as: Psoriasis Area and Severity Index (PASI) · PASI-Score · Psoriasis Alan ve Şiddet İndeksi (PASI)
What it is for
The Psoriasis Area and Severity Index (PASI) is a clinician-rated measure of plaque psoriasis severity that combines lesion intensity and extent in four body regions into one total from 0 to 72 (higher = more severe).
Classification
| Category | Description |
|---|---|
| Regions and weights | head and neck ×0.1, upper limbs ×0.2, trunk ×0.3, lower limbs ×0.4 (approximate share of body surface). |
| Intensity | in each region erythema (redness), induration (thickness) and desquamation (scaling) are each scored 0 none, 1 mild, 2 moderate, 3 severe, 4 very severe. |
| Area score | share of the region involved: 0 = none, 1 = under 10%, 2 = 10–29%, 3 = 30–49%, 4 = 50–69%, 5 = 70–89%, 6 = 90–100%. |
| Calculation | for each region (sum of the three intensity scores) × area score × region weight; the four regional values are added; range 0–72. |
| Note | no single universally fixed set of mild/moderate/severe PASI bands exists; response is often reported as percentage improvement from baseline (e.g. PASI 75, PASI 90). |
Source
Severe psoriasis – oral therapy with a new retinoid
Dermatologica 1978;157:238–244 (Fredriksson T, Pettersson U)
DOI: 10.1159/000250839
PMID: 357213
- Edition
- Fredriksson & Pettersson 1978 (unchanged scoring in current use)
- Checked on
Summary of the published classification in our own words. Not a substitute for the original publication.
A question about this classification?
Medelix answers clinical questions from guidelines and studies – every statement with its source.