427 Clinical Correlation of Prick and Prick-to-Prick Skin Tests to Food in a Group of Children with Allergy Symptoms

BACKGROUND: The food hypersensitivity IgE-mediated in children is of 1.6% to 6%. It can be manifested clinically as allergy in different devices and systems. Skin prick tests have a positive predictive value of less than 50% and 95% of negative predictive value. Prick-to-Prick tests have not been studied extensively. OBJECTIVE: To clinically correlate food hypersensitivity to Prick and Prick-to-Prick tests in a group of children with allergy symptoms in the skin, the gastrointestinal tract and the respiratory system. METHODS: A retrospective study done in the department of Pediatric Allergy of a Children's Hospital from June 2008 to May 2011. Data was taken from the records of 100 patients who gave positive to Prick and Prick-to-Prick food tests. We also looked for the clinical setting referred to by the patient. The frequency and CI 95% were analyzed by Chi(2). Out of the 100 patients, 48 were female and 52 male. These patients were grouped by age range. Fifteen patients fall within 1 to 2 years range, 15 patients fall within the 3 to 5 year range and 26 patients within the over-6-years range. Twenty patients presented asthma, 16 allergic rhinitis, 24 atopic dermatitis, 33 food allergy, 5 gastrointestinal eosinophilia, and 2 children presented other reactions. The tests were done with extracts of IPI ASAC Laboratories and fresh food. We considered that the tests that were positive were those with a wheal diameter greater than 3 mm over the negative control. RESULTS: 10%(95% CI, 4.12-15.88) of the patients had a reaction after the Prick test and presented clinical symptoms of which 30% were cutaneous and 70% gastrointestinal. Thirty six percent of the patients had a reaction after the Prick-to-Prick test (95% CI, 26.59-45.40)[P = 0.005] of which 17% developed respiratory symptoms, 22% skin, and 61% gastrointestinal. The main fresh foods with which the patients gave positive were: milk 16% (95% CI, 8.81-23.18), egg 10% (95% CI, 4.12-15.88), and wheat 7% (95% CI, 1.99-12.00). Prick tests like milk, eggs and corn could not be assessed properly by the sample size. CONCLUSIONS: Prick-to-Prick tests are more effective than Prick to detect patients with food clinical reactions.