Skin prick tests identify asthma risk for toddlers with eczema

Toddlers with eczema who have a positive skin prick test for allergy have almost triple the risk of developing asthma than those with a negative test, says an Australian study.

The study, led by the University of Melbourne, is the first to clearly demonstrate that skin prick tests can be used to assess how likely it is a baby or toddler with eczema will go on to develop asthma later in childhood.

Researcher Adrian Lowe, from the University of Melbourne’s School of Population Health, says the study shows that toddlers who have positive skin prick tests have a much higher risk of developing asthma by the time they are seven.

They are also more likely to develop hayfever, particularly if their skin prick test results suggest a possible food allergy.

“There has been much discussion about the links between eczema and other allergic diseases such as asthma but this study is the first to clearly demonstrate that among children with eczema there are certain groups who are at much higher risk,’’ Mr Lowe says.

As part of the study, 620 Melbourne children with eczema were skin prick tested for allergies to cows’ milk, egg white, peanut, house dust mite, rye grass and cat hair.

Skin prick tests were conducted on the children at six months, one and two years of age. The children’s allergy status was then followed up five years later when the children had turned seven.

The study, published in the international journal Clinical and Experimental Allergy, also included researchers from the John Hunter Children’s Hospital, Monash University and Murdoch Children’s Research Institute.

Mr Lowe says the study shows that skin prick testing may have benefits for the management of childhood allergies.

“By identifying high risk children we can explore ways of avoiding potential allergens that could exacerbate their condition,” he says.

Mr Lowe says although eczema is extremely common – affecting up to 20 per cent of children – only a very small percentage are tested for allergy.

“Given that specialist allergy testing requires a referral and long waiting lists it is not surprising that children are rarely tested,” he says.

Mr Lowe says the study also shows how skin prick testing has the potential to boost future research into the links between eczema and other allergic diseases.

“Previously researchers have studied children with eczema as if they were one homogenous group,’ he says. “By showing that there are two distinct categories of children with eczema, future studies can separate these groups and we may be able to more accurately pinpoint the causes of allergic diseases in the longer term.”

(Source: Clinical and Experimental Allergy: Janine Sim-Jones: The University of Melbourne: March 2008)