Eczema and allergy: how useful is allergy testing?

Objective: To determine the value of allergy testing using skin prick tests and specific immunoglobulin E measurements (spIgE) to identify allergies in children with eczema (atopic dermatitis) and to correlate these findings with the clinical history

Methods: This was a retrospective study of 100 children with moderate to severe eczema attending hospital for treatment. In each child a detailed clinical history of allergy was documented and the severity of atopic dermatitis assessed by the research nurse. Skin prick tests were carried out using grass pollen, house-dust mite and egg-white allergens. Blood tests were taken for total IgE and spIgE responses to these allergens. A control group of 100 children with no history of allergy was also included for comparison.

Results: More than two thirds of the children (68 per cent) had a high total IgE (> 1000 kU/l). SpIgE tests to grass and house-dust mite were shown as the most frequent finding although statistically poor in association with the clinical history. Allergy to these airborne allergens was found to be more common in the older age group of children. whereas egg-white allergy was seen more commonly in the younger age group.

Conclusions: There is no one diagnostic test for allergy in children with atopic dermatitis. The results of these tests in combination with the clinical history provide a more accurate assessment of the child's allergy status. Children with moderate to severe eczema have a high incidence of associated allergy. Skin prick tests and spIgE proved helpful but neither was exclusively better than the other for diagnosis. The clinical nurse specialist is able to make a valuable contribution to the family through offering support and carrying out allergy tests.