Skin barrier therapy for AD and FA prevention
Consequently, skin care interventions in early life have been explored as a strategy for AD and FA prevention, through reduction of transepidermal water loss (TEWL) and skin barrier repair before onset of disease. In 2014, two separate randomized controlled trials (RCTs) from USA/UK and Japan were published simultaneously, demonstrating that the application of moisturizers in high-risk infants with a family history of AD in the first 2 months of life reduced AD risk by age 6 and 9 months.28, 29 Horimukai et al28found no significant differences in egg sensitization at 32 weeks, but Simpson et al29 did not assess food sensitization or FA outcomes. In 2020, two large randomised controlled trials conducted in Norway / Sweden (Preventing Atopic Dermatitis and ALLergies in childhood - PreventADALL study) and the United Kingdom (Barrier Enhancement for Eczema Prevention – BEEP study) also failed to demonstrate any effect of skin emollient applications on AD development in normal-risk (PreventADALL) or high-risk (BEEP) infants.(Table 1)30, 31 PreventADALL further found that there was also no benefit of this intervention against food sensitization or FA by age 36 months.32 The BEEP study, however, showed a trend towards increased FA in children who received the skin intervention, although this was statistically non-significant.31 The Prevention of Eczema By a Barrier Lipid Equilibrium Strategy (PEBBLES) pilot study in 80 infants used a ceramide-dominant triple lipid moisturizer in high-risk infants from the first 3 weeks of life for 6 months, and reported a trend towards reduced incidence of AD and food sensitization at age 12 months.33 Longitudinal follow up is still ongoing to assess the impact of this intervention on food allergy outcomes.34 The Short-term Topical Application to Prevent Atopic Dermatitis (STOP AD) trial found that daily application of an emollient containing ceramides, fatty acid and oats for the first 8 weeks of life reduced the incidence of atopic dermatitis at age 6 and 12 months in high-risk infants, compared to standard skin care.35 There were, however, no significant differences in food sensitization rates between both groups, but its impact on food allergy could not be assessed due to small numbers.
A Cochrane meta-analysis by Kelleher et al found that all types of early skin interventions, inclusive of bath oils, bathing practices as well as emollients, anytime in the first year of life were not protective against AD development, and could potentially increase the risk of skin infections.36 Another meta-analysis examined the effect of only emollients in the first 6 weeks of life on AD development at any age and found that this intervention was potentially efficacious in high-risk populations but not in normal-risk infants; might delay rather than completely prevent AD onset; and was of benefit if applied continuously rather than with an interval between treatment cessation and AD outcome assessment.37 Both meta-analyses found a similar trend towards increased food sensitization, albeit powered only by the BEEP study at that time.