In vitro testing in pediatric food allergy

Food allergies are an important cause of morbidity in the pediatric population. We used a questionnaire to assess the value of in vitro testing in evaluating children for food allergy. The patient population was divided into two groups: those who tested positive (Class I or greater) for food allergy (combined food/inhalant allergy or food allergy alone) and those who tested negative for food allergy (inhalant only or negative test). Although we recognize that a significant proportion of food allergies may not be IgE-mediated, for the purposes of this study we considered a patient food allergy--positive if in vitro testing was positive and food allergy--negative if testing was negative. Thirty-eight of 77 patients tested (49%) were positive for food allergies. Those with food allergies did not have pretreatment scores significantly different from those of patients negative for food allergies (55 vs. 65, p = 0.11). Similarly, we detected no statistically significant difference between the symptom-improvement scores of the two groups (37 vs. 40, p = 0.57). We conclude that in vitro testing for food allergies is warranted in children with allergic symptoms, for several reasons: The prevalence of IgE-mediated food allergy in children may be higher than previously thought, and children with food allergies experience the same severity of symptoms as those without. It must be remembered that in vitro testing only detects IgE levels, and therefore a negative test does not mean that the patient does not have food allergies. However, when positive, in vitro testing gives the physician the opportunity to modify the treatment plan, helping avoid time-consuming and demanding oral food challenges. Our questionnaire also showed that food allergy and non-food allergy patients had similar pretreatment and posttreatment symptom scores.