Food Allergy- An Overview - PowerPoint Presentation

1. Food Allergy- An OverviewNaveena Bobba MDFriday October 23, 2015

2. Objectives1. Understand the presentation of IgE mediated food allergy2. Identify the appropriate patients to skin test for food allergy3. Understand the management of food allergy

3. Case Study GK is an 18 yo M coming in for concerns about food allergyNotes that for the last year has had episodes of lip tingling and itching in throat and lips, mainly after eating. Decided to make an appointment because a few weeks ago actually had lip swelling. No history of asthma or atopic dermatitis, although thinks his younger brother had eczema as a child, and everyone in the family has hayfever

4. Adverse reactions to food can be categorized as immunologic or non immunologicFood intolerance can include metabolic, pharmacologic, toxic, and/or undefined mechanismFood allergy- Adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given foodImmune responses can be IgE or non-IgE mediated~13% self report having food allergy, 3% prevalence based on OFCData to suggest that peanut allergy has tripled since late 90's Food AllergySampson, H, et al. Food Allergy: A Practice Parameter Update-2014. JACI, 2014; 134(5):1016-25.

5. Adverse Food Reactions

6. IgE mediated food allergyIncludes classic allergic mediated symptoms resulting from exposure of food Mod-severe Atopic Dermatitis is a significant risk factor for food allergy Diagnosis is clinical, testing can help Symptoms generally occur within minutes to hours after ingestion Food allergy is more common in children.A limited number of foods account for the most significant food allergies: Milk, egg, soy, wheat, peanut, tree nut, shellfish, fish.Food allergy more common in people with atopic diseases.

7. In individuals presenting with anaphylaxis or related symptoms that occur within minutes to hours of ingesting food, especially in young children and/or if symptoms have followed the ingestion of a specific food on more than 1 occasionMost commonly have cutaneous involvement: urticaria, angioedema or erythemaCan also involve GI tract (most commonly vomiting), respiratory system and CV systemSuspect Food Allergy…..Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-Sponsored Expert Panel. JACI, 2010; 126(6):S1-58.

8. Critical questions should include the following:What are the symptoms of concern?What food precipitates the symptoms, and has this food caused such symptoms more than once?When did symptoms occur in relation to exposure to a given food?What quantity of food was ingested when the symptoms occurred?Was the food in a baked (extensively heated) or uncooked form?Can the food ever be eaten without these symptoms occurring?Have the symptoms been present at times other than after exposure to a given food?What treatment was given, and how long did the symptoms last?History for FAGuidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-Sponsored Expert Panel. JACI, 2010; 126(6):S1-58.

9. Allergy tests yield information on sensitizationIndicates presence of food specific IgETesting must be correlated with history and physical exam to determine clinical diseaseSensitized patients may tolerate foodFalse Positive Tests- both skin and blood tests are poorly specific, up to 50-60%False Negative Tests- Negative tests occasionally occur in patients with IgE-mediated FA. Skin test diameter and RAST levels do correlate with likelihood of reaction, but not severityTesting for Food Allergy

10. Positive Predictive Values

11. When skin testing or IgE antibody test results do not confirm the clinical history, or the history is not definitive then an oral food challenge (OFC) may be warranted Perform an open oral food cost- and time-efficientPatient characteristics that increase the risks associated with OFCs include having a history of a previous severe reaction or history of reaction after ingestion of trace amounts of the causal food.Concomitant medical conditions, such as asthma or respiratory tract infection, should be considered before performing OFCs.Delay or defer OFC for those with uncontrolled urticaria or ADConfirming FA

12. Allergen-Directed Treatment Plans for Food AllergyDiscussion of avoidanceLabel reading, cross-contact in food preparation, restaurantsFor children- work with parents to inform staff in special settingsDiscussion of medical management of anaphylaxisIngestion is the most likely route for triggering severe allergic/anaphylactic reactionsDevelop a written action plan for treatment of allergic reactionsIndications and technique of self-injectable epinephrinePractice techniqueEnsure Epi pens are accessible and up to dateResources: The Food Allergy & Anaphylaxis Network (www.foodallergy.org); American Academy of Allergy, Asthma and Immunology (www.aaaai.org); American College of Allergy, Asthma and Immunology (www.acaai.org)

13. Natural History of Food AllergyCertain food allergies in children can resolve with timeMost common in milk, egg, wheat and soy allergiesRetest yearly to see if sensitization is decreasingAllergy to peanut, tree nut, fish and shellfish are usually more persistent20% tolerance to peanut with time, 10% to tree nutIf testing indicates decreased sensitization can consider an OFCIf OFC is passed, family should work at incorporating food into diet.

14. PreventionNo recommendation for mother’s to avoid foods during pregnancy or with breast feedingDo not delay introduction of foods in infantsIncreased risk for food allergy or atopic dermatitis- in reference to primary preventionSecondary prevention may need to consider a more cautious approach

15. A Few Words on LEAPRandomized infants to early peanut introduction or avoidanceInfants were from 4-6 months old and either had severe eczema or egg allergyPrimary outcome was clinical peanut allergy at 5 years oldMain results:Large reduction in development of peanut allergy in infants randomized to early introduction

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17. LEAP study: ResultsDu Toit et al, NEJM 2015;372:803-813

18. Case Study GK is an 18 yo M coming in for concerns about food allergyNotes that for the last year has had episodes of lip tingling and itching in throat and lips, mainly after eating. On further probing this seems to occur with ingestion of apples, melons and peaches. A few weeks ago he was eating a cantaloupe and developed lip swellingHe does give you a history of rhinitis. When living on the East Coast with his family had symptoms in spring/fall- told he was allergic to trees and ragweed. Now has symptoms year long

19. Oral Allergy Syndrome (OAS)Oral allergy syndrome is caused by cross-reacting allergens found in both pollen and raw fruits, vegetables, or some tree nuts. The immune system recognizes the pollen and similar proteins in the food and directs an allergic response to itOAS most commonly affects patients who are allergic to (specific) pollens (eg, ragweed and birch). Symptoms include pruritus and/or tingling of the lips, tongue, roof of the mouth, and throat with or without swelling. Systemic clinical reactions are rare.

20. Oral Allergy SyndromeSampson, H, et al. Food Allergy: A Practice Parameter Update-2014. JACI, 2014; 134(5):1016-25.

21. Take Home PointsThe history is critical in the diagnosis of food allergy and is the first step in discerning both the type of food allergy present and the suspected causative food.Skin testing for food-specific IgE is used only in the diagnosis of IgE-mediated food allergies. Skin testing is more sensitive than in vitro testing in many cases Testing in a guide, on occasion a supervised food challenges may required for the definitive diagnosis of food allergy

22. Questions????