Palmar hyperlinearity is associated with persistent atopic dermatitis trajectory with high allergic risk: The yamanashi adjunct study of the Japan environment and Children's study

Palmar hyperlinearity (PH) is a minor diagnostic criterion for atopic dermatitis (AD) proposed by Hanifin and Rajka and is associated with loss-of-function variants in the filaggrin (FLG) gene. Although FLG variants are linked to the long-term course of AD, evidence on the relationship between PH and AD trajectories is limited. We investigated the association between PH and long-term AD outcomes in children. We analyzed data from 1769 children in the Yamanashi Adjunct Study of the Japan Environment and Children's Study. PH was assessed by pediatric allergy specialists blinded to AD trajectories and by an artificial intelligence (AI)-based assessment. AD trajectories were identified using longitudinal latent class analysis based on eight assessments between 6 months and 6 years of age. Associations between PH and AD trajectories were examined using multinomial logistic regression with the never/infrequent group as reference. PH was identified in 34 children (1.9%) and AI-based PH in 10 (0.6%). Four AD trajectories were identified: persistent (8.5%), early-onset (16.7%), late-onset (10.3%), and never/infrequent (64.6%). PH was significantly associated with persistent AD (adjusted OR 3.60, 95% CI 1.49-8.67) but not with early- or late-onset phenotypes. Similar findings were observed for AI-based PH. Persistent AD was also associated with allergic symptoms (food allergy, asthma, allergic rhinitis) at age 6 and allergic sensitization at age 8. PH was associated with an AD phenotype characterized by a more persistent disease course.