Intrinsically defective skin barrier function in children with atopic dermatitis correlates with disease severity

Background: Recent genetic evidence supports that an underlying defect in skin barrier function contributes to the pathogenesis of atopic dermatitis (AD). The integrity of the skin barrier can be assessed objectively by measuring transepidermal water loss (TEWL). Previous investigations of TEWL as a biomarker of skin barrier function have been limited by small sample size, and studies including African American subjects are lacking. Objective: We sought to determine whether children with AD have inherently altered skin barrier function by comparing TEWL as a measure of skin barrier function in African American and white children with AD with that in control subjects without AD. Methods: TEWL was measured on nonlesional normal-appearing skin at 4 sites (the volar forearm, dorsal arm, lower leg, and cheek) in (1) children with AD (cases), (2) children with asthma or allergic rhinitis but without AD (allergic control subjects), and (3) nonatopic control subjects. AD severity was assessed by using the objective SCORAD index. Results: TEWL was increased in children with AD compared with that seen in both control groups at most of the anatomic sites tested (P < .05). TEWL also correlated with objective SCORAD score. The presence of allergic sensitization or other allergic conditions did not affect TEWL among children with AD. TEWL was higher in white than in African American children. Conclusion: Skin barrier function as assessed by TEWL is intrinsically compromised in children with AD but not in children with other allergic conditions. The magnitude of skin barrier dysfunction correlates with AD disease severity.