Louisville Medicine Volume 66, Issue 2 - Page 28

FEATURE DON’T GO NUTS: The Current View of Food Allergies Wes Sublett, MD F ood allergy is an important public health problem as it affects count- less children and adults. Food aller- gies affect up to six to eight percent of children, and two to three percent of adults. The incidence of food allergies has increased significantly over the past 20 years. In the US, peanut allergy has more than tri- pled between 1997 and 2008, and food allergy related emergency visits nearly tripled in a four-year period. Although many foods have been documented to cause allergic reactions, cow’s milk, hen’s eggs, peanuts, tree nuts, fish and shellfish are responsible for most serious allergic reactions. Although most egg and cow’s milk allergies resolve in early childhood, the development of spontaneous tolerance to peanut or tree nut allergies occurs in less than 20 percent of patients. Patients and their families experience significant anxiety related to fear of accidental exposures leading to allergic reactions. 1-5 Food allergy results in significant direct medical costs for the US health care system and even larger costs for families facing food allergy. In a cross-sectional survey of 1,643 US caregivers of a child with a current food allergy, the overall economic cost was estimated at $24.8 billion annually ($4,184 per year per child). Direct medical costs were $4.3 billion annually including clinician visits, emergency department visits and hospitalizations. Costs borne by the families totaled $20.5 billion annually, including lost labor productivity, out-of-pocket and opportunity costs. 6 Food allergy is most often caused by a specific IgE-mediated 26 LOUISVILLE MEDICINE reaction to a food protein with the potential to cause food-in- duced anaphylaxis, a serious allergic reaction that is rapid in onset and may cause death. Foods triggers have been identified in other non-IgE-induced mechanisms, including food protein-induced enteropathy (FPIES), exacerbations of eosinophilic GI disorders (EGIDs) (eosinophilic gastritis, eosinophilic enteritis, eosinophilic colitis, and eosinophilic gastroenteritis), and food-induced allergic contact dermatitis. For the sake of this article, we will focus on only IgE mediated food allergy. 5 Medical history is the most critical part of making an accurate diagnosis of food allergy. Food allergy is typically characterized by a defined exposure to a food allergen that is followed by a rapid onset and evolution of multiple symptoms involving multiple organ systems. If food allergy is suspected, the patient should then be evaluated by a board-certified allergist to confirm the diagnosis. At that time, additional diagnostic modalities include skin prick testing to specific food allergens and specific serum IgE blood test may be done. “Routine” panels of food skin prick testing or in-vitro specific serum IgEs should not be ordered without a historical rationale and tolerated foods (foods ingested without problems) need not be tested. False positive prick and in-vitro testing, without a supporting history, may cause needless anxiety and unnecessary elimination of foods. Oral food challenges remain the gold standard for diagnosis of food allergy. However, challenges are time and resource intensive and carry the risk of an anaphylactic reaction. Neither skin prick testing nor specific IgE blood test results alone are considered suffi-