A pilot study on the Psoriasis Area and Severity Index (PASI) for small areas: Presentation and implications of the Low PASI score

Abstract

Background: The Psoriasis Area and Severity Index (PASI) is not able to measure small affected areas in a body region which is important for assessing the performance of high-effective treatment.

Objective: To present the Low PASI score, show the difference between the classic PASI and the Low PASI, evaluate the inter-observer agreement of both scores, and compare the two scores within investigators.

Methods: Cross-sectional study. Two investigators independently assessed the classic PASI and the Low PASI in 10 patients with mild-to-moderate plaque psoriasis. Differences in outcome between the two scores were calculated. Intra-class correlation coefficients (ICC) were used to determine the inter-observer agreement and to compare measurements of the two scores within both investigators. Prediction limits of 95% for the errors in measurements were provided.

Results: In both investigators, Low PASI was mean 1.71 and 1.76, whereas the classic PASI was mean 4.14 and 4.33. The inter-observer agreement (ICC) was excellent for both investigators in both scores (ICC classic PASI = 0.95 and Low PASI = 0.87).

Conclusion: The Low PASI score allows more possible scores at lower levels of psoriasis extent (affected areas lower than 10% in a body region) compared to the classic PASI. This new score may lead to a more precise analysis of treatment responses and may have important clinical implications.

• Body surface area
• PASI
• psoriasis
• Psoriasis Area and Severity Index

Declaration of interest

The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper. The study was not funded by any external funding source.