EXPERT ANALYSIS FROM THE EADV CONGRESS
VIENNA (FRONTLINE MEDICAL NEWS) – Diverse strategies aimed at preventing childhood atopic dermatitis (AD) now under study include installation of home water softeners, daily use of emollients starting at birth, and maternal consumption of probiotics beginning late in pregnancy, Carsten Flohr, PhD, said at a joint program of the International Eczema Council and the International Psoriasis Council held in conjunction with the annual congress of the European Academy of Dermatology and Venereology.
To date there is no effective method for preventing AD. Preventive strategies are needed sorely because the prevalence of pediatric AD worldwide is expected to increase substantially. It appears to have stabilized at roughly 20% in many affluent countries, but the global burden of the disease will climb as low-income countries – where AD is historically uncommon – become more developed and urbanized. This trend has been well documented via the International Study of Asthma and Allergies in Childhood (ISAAC), which in several phases has studied nearly 2 million children in more than 100 countries, noted Dr. Flohr of St. John’s Institute of Dermatology at King’s College London.
Findings from two small randomized controlled trials totaling fewer than 300 infants at high risk for developing AD due to family history have shown that daily application of emollients from birth significantly reduced the incidence of the skin disease during the first year of life. The mechanism of benefit is thought to involve enhancement of skin barrier function. Two large randomized trials aimed at confirming these findings are now underway in the England and Sweden. If the results prove positive, intensive application of emollients would constitute an effective, safe, and cheap preventive strategy, he observed.
Dr. Flohr and coinvestigators in the Enquiring About Tolerance (EAT) study recently documented a significant association between water hardness and the risk of infant-onset AD. The investigators took advantage of the considerable variation in the amount of bedrock limestone across England, which enabled them to study the relationship between domestic water calcium carbonate concentrations and the presence of AD in 1,303 babies at 3 monthd of age drawn from the general population across the country. Filaggrin skin barrier gene mutation status was determined in all infants.
Infants whose water supply contained a calcium carbonate level above the median value were at an adjusted 46% greater risk of having visible AD at age 3 months than those whose household water calcium carbonate level was below the median. The AD risk rose by 1% for each 1 mg/L increase in calcium carbonate concentration above the median. This increased risk was confined to infants with a filaggrin skin barrier gene mutation; hard water didn’t increase early AD risk in children with the normal, wild-type version of the filaggrin gene ( J Allergy Clin Immunol. 2016 Aug;138:509-16 ).
As a result of these findings, a UK prevention trial is underway in which home water softeners are provided to families at high risk of having a baby with AD in water districts with high calcium carbonate concentrations. An earlier UK study found that installation of home water softeners didn’t reduce AD severity in children with established disease ( PLoS Med. 2011 Feb 15;8:e1000395 ), but disease prevention may be another story.
The role of the gut microbiota in development of childhood AD is an active area of investigation. Dr. Flohr said “there is a signal” that maternal intake of probiotics including lactobacilli and bifidobacteria in the third trimester and postnatally may reduce a child’s risk of developing AD by encouraging establishment of a more diverse gut microflora. He cited a meta-analysis of 14 published studies of probiotics which provided evidence of a 21% reduction in the incidence of AD in young children ( Epidemiology 2012 May;23:402-14 ). The studies have methodologic shortcomings, so multiple research groups are continuing to pursue the signal of an AD preventive effect.
Dr. Flor reported having no financial conflicts of interest regarding his presentation.