Boys who have eczema in their first two years of life are more likely to develop asthma later on, but there is no association between early eczema and asthma in girls, Australian researchers report.
"Further interventions that attempt to reduce the progression from eczema to sensitisation and asthma are warranted, particularly in boys," Adrian J. Lowe of the University of Melbourne and colleagues write in the Journal of Allergy and Clinical Immunology.
If eczema does lead to asthma, they add, preventing the skin condition could cut the incidence of childhood asthma by 28 percent.
Babies with eczema are thought to be at increased risk of asthma later on, a progression called the "atopic march," Lowe and his team explain. Atopy is an overall term for conditions caused by allergic hypersensitivity, but some researchers argue that wheeze and sensitisation must also be present for this progression to occur.
To investigate, the researchers followed 403 children from families with a history of allergic disease. Among boys with eczema, the risk of being diagnosed with asthma by age seven was 2,45 times greater than for boys without eczema. Girls with eczema were actually 12 percent less likely to have asthma later on, but this was not a statistically significant difference.
While sensitisation to allergens and wheeze were also related to asthma risk, the researchers found, the eczema-asthma link remained after sensitisation and wheeze were taken into account.
Several differences exist between boys and girls in terms of asthma, lung development, and skin structure, the researchers say. "Given these differences, it is not surprising that eczema could have different effects on risk of asthma in boys and girls," they add.
Eczema may represent loss of the skin's ability to act as a barrier between the body and the environment, which could make sensitisation to allergens more likely, Lowe and his team suggest.
If this is the case, they say, restoring the skin's barrier function could prevent asthma. While standard moisturisers can't do this, the researchers add, an emollient containing the fatty ingredients of human skin - ceramides, cholesterol and free fatty acids - has been shown to speed barrier function repair.