PASI
Pronunciation: PAY-see
Also written as: PASI — Psoriasis Area and Severity Index
An acronym for Psoriasis Area and Severity Index, a validated scoring tool quantifying the extent and severity of psoriatic skin involvement.
Full Definition
The Psoriasis Area and Severity Index (PASI) is a composite clinical scoring system that assesses the area of body involvement and the severity of three signs — redness (erythema), thickness (induration), and scaliness (desquamation) — across four body regions: head, trunk, upper limbs, and lower limbs. Scores range from 0 to 72; a score ≥10 is commonly used to define moderate-to-severe psoriasis in clinical trial eligibility criteria and treatment guidelines. Editors reviewing pharmaceutical manuscripts, clinical trial protocols, or health technology appraisals will encounter PASI extensively, typically alongside PASI 75/90/100 response thresholds (indicating 75%, 90%, or 100% improvement). The acronym is always written in uppercase and must be expanded at first use.
Usage
Usage note: Expand at first use. PASI 75, PASI 90, and PASI 100 refer to percentage improvement thresholds from baseline; these must not be confused with absolute PASI scores.
In Context
- "At week 16, 68% of patients in the treatment arm achieved a PASI 90 response compared with 5% in the placebo group." — Phase III clinical trial manuscript
- "Expand 'PASI' at first use as 'Psoriasis Area and Severity Index (PASI)' and check that PASI 75/90/100 thresholds are defined in the methods section." — Peer-review editorial instruction