Catherine M. Bettcher, M.D. CME Director & Assistant Professor, Department of Family Medicine, University of Michigan No Nuts Allowed: Food Allergies in Children

Learning Objectives Understand appropriate methods to diagnose food allergy Implement strategies to manage children with food allergy Apply evidence-based recommendations for prevention of food allergies Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-Sponsored Expert Panel. Dec 2010

Why Bother? Probably becoming more common Reactions can be life-threatening Affects meal preparation and family social activities May cause anxiety and poorer quality of life among parents

Definition of Food Allergy Adverse health effect Caused by a immune response Reproducible Exposure to specific food Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-Sponsored Expert Panel. Dec 2010

Prevalence of Food Allergy

Major Food Allergens in U.S.

Prevalence of Specific Food Allergies

Risk Factors for Food Allergy Family history of atopic disease Presence of atopic dermatitis ? Changes in diet ? Hygiene hypothesis (dirt = good) ? Exposure to food allergens

When to Suspect Food Allergy Child develops anaphylaxis or symptoms typical of allergic reactions (urticaria, pruritis, angioedema) on exposure to food – Occurs shortly after ingesting food – Occurs consistently following ingestion Infant or young child has a certain disorder that is highly associated with food allergy

Diagnosis of IgE-Mediated Food Allergy Not based on history and physical exam Must be confirmed by appropriate tests – Skin prick test – Allergen-specific serum IgE – Oral food challenge

Skin Prick Test (SPT) ProsCons SafeLow specificity (over-diagnosis) Inexpensive High sensitivity

Allergen-Specific Serum IgE ProsCons Routinely availableMore expensive Easy to performVariable sensitivity Not affected by medicationVariable specificity (over-diagnosis) Can be done with skin diseaseDifferent assays not comparable No risk of allergic reaction

Double-Blind, Placebo-Controlled Oral Food Challenge ProsCons Gold-standardExpensive High specificityTime-consuming Requires specialized personnel Risk of severe allergic reaction

Severity of Allergic Reaction Based on amount of food ingested and food form Cannot be predicted by: 1. Degree of severity of past reactions 2. Level of allergen-specific IgE 3. Size of wheal on skin prick test Children with asthma are more likely to have severe reactions

Treatment of Food Allergy

Management of Food Allergy Allergen avoidance Oral antihistamine and injectable epinephrine prescriptions Nutritional counseling and education ( Regular growth monitoring Education in schools/childcare centers

Natural History of Food Allergy About 85% of children with food allergy eventually tolerate milk, egg, soy and wheat Less likely to resolve in children with higher levels of allergen-specific IgE Time to resolution of food allergy varies Consider reevaluating patients every 1-2 years

Prevention of Food Allergy Avoiding specific foods while pregnant or breastfeeding does not prevent food allergy No difference between cow’s milk infant formula and soy infant formula Delaying the introduction of solid foods does not prevent food allergy

Feeding and Atopic Disorders InterventionAsthmaAllergic rhinitisEczema Breastfeed > 9.5 monthsDecrease Cereal before 5.5 monthsDecrease Cereal before 4.5 monthsIncrease Egg before 11 monthsDecrease Fish before 9 monthsDecrease J Allergy Clin Immunol 2013;131:78-86

Learning Early About Peanut Allergy (LEAP) trial 640 high-risk infants 4 to 11 months old – Randomized to eat peanuts 3 d/wk vs. complete avoidance until 5 yrs old Peanut avoidance group had a higher risk of peanut allergy (17.2%) compared to peanut consumption group (3.2%)

Take home points Don’t presume that “food allergies” are true allergies Beware of false positives Refer to nutritionist (Food Allergy Program) Introduce foods early

Choosing Wisely Don’t perform food IgE testing without a history consistent with potential IgE-mediated food allergy. Don’t perform screening panels for food allergies without previous consideration of medical history.

References Boyce JA et al. NIAID-sponsored expert panel. Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID- sponsored expert panel. J Allergy Clin Immunol. 2010;126(6 Suppl):S1-58. Du Toit G et al. Identifying infants at high risk of peanut allergy: the Learning Early About Peanut Allergy (LEAP) screening study. J Allergy Clin Immunol. 131(1): e1-12, 2013 Jan. Lack GL. Epidemiologic risks for food allergies. J Allergy Clin Immunol. 2008;121(6): Lieberman JA, Sicherer SH. Diagnosis of food allergy: epicutaneous skin tests, in vitro tests, and oral food challenge. Curr Allergy Asthma Rep. 2011;11: Liu AH. Hygiene theory and allergy and asthma prevention. Paediatric and Perinatal Epidemiology. 2007;21(Suppl. 3):2-7. Nwaru BI et al. Timing of infant feeding in relation to childhood asthma and allergic diseases. J Allergy Clin Immunol. 131(1):78-86, 2013 Jan.

References Okada H, Kuhn C, Feillet H, Bach JF. The ‘hygiene hypothesis’ for autoimmune and allergic diseases: an update. Clinical and Experimental Immunology. 2010;160:1-9. Schneider Chafen JJ, Newberry SJ, Riedl MA, et al. Diagnosing and managing common food allergies. JAMA. 2010;303(18):