The predictive value of allergen skin prick tests and IgE tests at pre-school age: The PACT study

BackgroundSensitization toward allergens, as determined by skin prick test (SPT) or specific IgE (sIgE), is a predictor for the later presence of allergy-related disease (atopic eczema, allergic rhinoconjuctivitis and asthma). However, it is not known whether SPT or sIgE should be the preferred test. The aim of this study was to compare the predictive ability of SPT and sIgE when performed in a general population of 2-yr-old children. MethodsIn a prospective, longitudinal population-based study of children aged 2-6yr, SPT and sIgE for nine common allergens were performed at 2yr. Allergy-related disease was evaluated by clinical examination and questionnaire at 2 and 6yr of age (n=199). ResultsSkin prick test or sIgE was positive in 10.6% and 21.1% in the 2-yr-old children, respectively. The prevalence of allergy-related disease was 25.6% at 2yr and 25.1% at 6yr. Half of the cases at 2yr were transient. Both SPT and sIgE were statistically significant predictors for later allergy-related disease, OR=6.5 (95% CI 2.3-18.6) and OR=4.1 (95% CI 1.9-9.0), respectively. Receiver operating characteristic analysis showed that SPT and sIgE had comparable predictive ability for atopic eczema, asthma or any allergy-related disease, but sIgE had better ability to predict later allergic rhinoconjunctivitis. ConclusionSensitization at 2yr may be useful predictors of allergy-related disease later in childhood. The predictive ability of SPT and sIgE were mainly comparable; however, it may be that sIgE is the preferred choice in young children when the aim is to predict allergic rhinoconjunctivitis.