The Proposed PASI-HD Provides More Precise Assessment of Plaque Psoriasis Severity in Anatomical Regions with a Low...

The Psoriasis Area and Severity Index (PASI) is the most widely used clinical measure in clinical trials to assess disease severity of plaque psoriasis. However, the PASI is not a precise measure of severity with less precision when the regional area of involvement is < 10% of the BSA of a specific anatomical region. Degradation of precision results from the area score defaulting to '1' when the area of involvement within an anatomical region falls between 0% and 10% of the BSA for a given anatomical region. We describe a modification to the PASI, termed PASI-high discrimination (PASI-HD), for determination of more accurate psoriasis severity in body regions where < 10% of the body surface area is affected. The methodology for assessing disease severity in these conditions is described.