Psoriasis Area and Severity Index (PASI)

A standardized tool for assessing the severity and extent of psoriasis based on lesion characteristics and body surface involvement.

Psoriasis Area and Severity Index (PASI)

Evaluate each of the four body regions and record the appropriate score.

HEAD/NECK

Erythema none

+0

slight

+1

moderate

+2

severe

+3

very severe

+4

Induration/thickness

none

+0

slight

+1

moderate

+2

severe

+3

very severe

+4

Desquamation/scaling none

+0

slight

+1

moderate

+2

severe

+3

very severe

+4

Percentage of area affected Validated using palm method of body surface area estimation (patient’s palm, excluding fingers, roughly correlates to 1% BSA) 0% 1-9% 10-29% 30-49% 50-69% 70-89% 90-100%

Head/Neck

Upper Limbs

Trunk

Lower Limbs

Interpretation

Sources:

Fredriksson T, Pettersson U. Severe psoriasis--oral therapy with a new retinoid. Dermatologica.1978;157(4):238-44. doi: 10.1159/000250839. PMID: 357213.
Feldman SR, Krueger GG. Psoriasis assessment tools in clinical trials. Ann Rheum Dis. 2005 Mar;64 Suppl 2(Suppl 2):ii65-8; discussion ii69-73. doi: 10.1136/ard.2004.031237. PMID: 15708941; PMCID: PMC1766877.