Eczema and allergy: how useful is allergy testing?

Abstract

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.

Trigger Factors, Allergens and Allergy Testing in Atopic Dermatitis

“…It must be interpreted in the context of clinical history, clinical signs and allergen exposure. The size of the weal does not necessarily correlate with severity of clinical reaction (Robinson & Smart, 2008& Goodwin, 2008. The RAST detects free allergen specific IgE in serum.…”

“…Positive RAST results indicate the presence of IgE to an allergen or cross reacting allergen, and are difficult to interpret in the presence of high levels of total IgE (>1000kU/L). Results therefore must always be interpreted in the context of clinical history (Robinson & Smart, 2008& Goodwin, 2008. APT is epicutaneous application of inhalant and food allergens on unaffected skin of AD individuals eliciting a delayed, type IV hypersensitivity reaction.…”

“…Negative RAST, SPT and APT results have a high negative predictive value and are fairly reliable methods of excluding allergy. Positive results however require careful consideration and correlation with clinical history and clinical presentation (Robinson & Smart, 2008& Goodwin, 2008. Sensitization to aeroallergens appears to be more prevalent in older children and adults, leading to aggravation of AD after bronchial inhalation.…”

“…The appearance of eczematous skin lesions is due to cytotoxic T-cell activity and not to the aeroallergen specific IgE. Repeated epicutaneous allergen application has been shown to elicit eczematous lesions in AD individuals & Goodwin, 2008.…”

“…Pseudo allergic reactions are more known in the clinical context of urticaria and angioedema. To date no reliable laboratory or skin tests are available to diagnose pseudo allergy, so that for the identification of possible pseudo allergen trigger factors elimination diet and oral challenge are the norm (Reese et al, 2009 (Robinson & Smart, 2008& Goodwin, 2008& Kim, 2008. SPT in the diagnosis of FA in infancy is thought to be unreliable.…”