PASI
Pronunciation: PAY-zee
Also written as: PASI — Psoriasis Area and Severity Index
Psoriasis Area and Severity Index; a composite scoring tool measuring the extent and severity of psoriasis across four body regions.
Full Definition
The PASI (Psoriasis Area and Severity Index) is the most widely used validated outcome measure in psoriasis clinical trials and guidelines. It combines assessments of erythema, induration (plaque thickness), and scaling across the head, trunk, upper limbs, and lower limbs, weighted by the body surface area affected in each region. Scores range from 0 to 72; a PASI 75 response (≥75% reduction from baseline) is the benchmark endpoint in clinical trials. Editors working on dermatology trial manuscripts must render PASI consistently in all-capitals and must not italicise or place it in quotation marks. Numeric response thresholds (PASI 75, PASI 90, PASI 100) should be written without a percent sign.
Usage
Usage note: Always render in all-capitals. Response thresholds (PASI 75, PASI 90) take no percent sign. Expand at first mention in clinical and research documents.
In Context
- "At week 16, 84% of patients in the treatment arm achieved a PASI 75 response compared with 6% in the placebo group." — Clinical trial results section
- "The editor standardized 'Pasi 75' to 'PASI 75' throughout the manuscript." — Manuscript copy-editing note