Determinants of disease severity among patients with atopic dermatitis: association with components of the atopic march.

We aimed to explore the association of key clinical characteristics with disease severity in atopic dermatitis (AD) and its relation to components of the atopic march in a large hospital cohort. Outpatients with AD referred to the Department of Dermatology, Bispebjerg Hospital, Copenhagen, Denmark, between January 2012 and December 2017, were compared based on disease severity (SCORAD); mild (< 25), moderate (25-50) and severe (> 50). A total of 470 AD patients were included: 122 small children (< 4 years of age), 103 children/adolescents (age 4-15 years) and 245 adults (> 15 years of age). A significant difference between severity groups in small children was observed for FLG mutation carrier status (16.7 vs. 30.2 vs. 60.0% mutation carriers among patients with mild, moderate and severe AD, respectively, p = 0.012) and self-rated health (3.2 vs. 2.7 vs. 2.8 with 4 being excellent health, p = 0.022). A significant difference between severity groups in adults was observed for male sex (24.4 vs. 39.8 vs. 52.9%, p = 0.003), serum total IgE (577 vs. 1269 vs. 2379 × 103 IU/L, p < 0.001), blood eosinophil count (0.28 vs. 0.39 vs. 0.61 × 109/L, p < 0.001) and asthma (42.9 vs. 38.8 vs. 72.0%, p < 0.001). Early onset of AD (< 1 year of age) and FLG mutation was associated with more severe disease and high serum total IgE levels. In conclusion, the distribution of key clinical characteristics varies significantly according to the severity of AD measured by SCORAD. Sub-typing of AD patients related to determinants of disease severity may be helpful in establishing prognosis and targeted treatment of AD.