PD10 The Photoaggravated Eczema Area and Severity Index: development and reliability of a clinical measure for photoaggravated atopic dermatitis

Abstract

To date, no clinical scoring systems exist to quantify atopic dermatitis (AD) disease manifestations in relation to solar radiation exposure. This is clinically relevant, as an estimated 1.4–16% of cases of AD constitute photoaggravated atopic dermatitis. Here, we introduce a modification of the Eczema Area and Severity Index (EASI), termed the Photoaggravated Eczema Area and Severity Index (PEASI), a novel tool to provide a standardized measure of AD severity and extent in relation to solar radiation, and report preliminary reliability data. The PEASI adapts the EASI framework by replacing conventional region weighting factors with predefined photoaggravated region weighting factors (PRWFs). These are calculated by weighting four photoexposed regions according to solar irradiance scaled by surface area and assigned as 0.40 ×, 0.10 ×, 0.20 × and 0.30 × for the face and V-area of the neck and upper chest, dorsal neck, dorsal arms and dorsal hands, respectively. The original area and severity scoring is preserved. Reliability was assessed using intraclass correlation coefficient (ICC) 2 : 1 metrics. A photoaggravated regional score is calculated as the product of the PRWF and the corresponding severity and area scores. The PEASI score is obtained by summing the photoaggravated regional scores. As both the RWFs and PRWFs sum to unity, the PEASI and EASI share identical score ranges. Two rounds of reliability assessment involving six cases of AD and eight assessors (seven dermatologists and one photodermatology technician across four institutions) demonstrated moderate-to-good inter-rater reliability (round one ICC 0.81, 95% confidence interval 0.58–0.96; round two ICC 0.70, 95% confidence interval 0.40–0.94) and good intrarater reliability (median ICC 0.84, interquartile range 0.73–0.96). The PEASI is not designed to replace the EASI in patients with photoaggravated AD. Rather, it serves as an instrument for the identifi­cation and longitudinal monitoring of photoaggravated disease. Preliminary reliability assessments provide support for its use as a reproducible measure of AD severity and extent in relation to solar radiation.