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.