Clegg et al reported response criteria for patients being treated for psoriasis. These can help to monitor a patient over time and to gauge the effectiveness of an intervention. The authors are from multiple Veterans Administration medical centers in the United States.


Patient selection: following therapy for psoriasis


Patient assessment:

(1) change in the percent body surface area (BSA) involved

(2) change in the severity of skin lesions (based on erythema, scaling and elevation)

State of the Psoriasis

Response Category

completely cleared (100%) with no evidence of psoriasis


76 to 99% improvement (significant reduction in lesions but with still some evidence of psoriasis)


50 to 75% improvement (partial)


25 to 49% improvement (partial)


about the same (< 25% improvement)


worse (progression)



If the PASI (Psoriasis Activity and Severity Index) score is used:


percent change =

= ((PASI before treatment) - (PASI after treatment)) / (PASI before treatment) * 100%


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