Validation of Head and Neck EASI Severity Strata Against vIGA-AD in Atopic Dermatitis.

BACKGROUND

Head-and-neck (H&N) Eczema Area and Severity Index (EASI) sub-scores are increasingly reported, but their clinical interpretation relative to the validated Investigator Global Assessment for Atopic Dermatitis (vIGA-AD) remains unclear.

OBJECTIVE

Define H&N EASI severity strata anchored to vIGA-AD and evaluate convergent validity and interrater reliability.

METHODS

Twenty-two dermatologists evaluated photographs of 21 patients with H&N AD using the H&N EASI and vIGA-AD. H&N EASI severity strata were derived based on the empirical distribution within vIGA-AD. Kendall's tau (τ) and Spearman's correlation coefficient (SCC) assessed convergent validity, and intraclass correlation coefficients (ICC) evaluated interrater reliability.

RESULTS

H&N EASI scores aligned with vIGA-AD (0, "Clear"; 0.1-0.6, "Almost clear"; 0.7-1.7, "Mild"; 1.8-3.0, "Moderate"; and 3.1-4.8, "Severe"), showing almost perfect agreement (weighted Cohen's κ = 0.83 [95% CI, 0.80-0.86], P < 0.001). H&N EASI and vIGA-AD scores were strongly correlated (τ = 0.74 [95% CI, 0.71-0.77]; SCC = 0.86 [95% CI, 0.83-0.88], both P < 0.001). Interrater reliability was moderate for H&N EASI (0.73 [95% CI, 0.60-0.85]) and vIGA-AD (0.61 [95% CI, 0.46-0.77]) (both P < 0.001).

CONCLUSIONS

H&N EASI severity strata provide a reliable and clinically meaningful assessment of H&N AD, aligning with facial vIGA-AD and enabling evaluation beyond global assessment.