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Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
Sat 1110-food-allergies- -seasons
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Sat 1110-food-allergies- -seasons

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  • 1. 5/26/2014 1 An Approach to Food Allergies Edmond S. Chan, MD, FRCPC Clinical Associate Professor, UBC Division of Allergy & Immunology June 7, 2014 BCCFP Spring 2014 Family Medicine Conference Vancouver Faculty/Presenter Disclosure • Faculty: Edmond Chan • Relationships with commercial interests: • Advisory board: Sanofi (Allerject) • Honoraria (CME lectures): Sanofi, Pfizer, Mead Johnson, Nestle CFPC CoI Templates: Slide 1
  • 2. 5/26/2014 2 Disclosure of Commercial Support • This program has not received financial support. • This program has not received in-kind support. • Potential for conflict(s) of interest: None CFPC CoI Templates: Slide 2 Mitigating Potential Bias • There is no potential bias with any products. CFPC CoI Templates: Slide 3
  • 3. 5/26/2014 3 Objectives • Discuss: How to diagnose food allergies • Examine: How to manage non-acute food allergies • Review: Update on the prevention of food allergy Case: 4 year old girl • Older brother with confirmed, multiple IgE mediated food allergy and eczema – Girl has mild eczema, parents afraid to introduce allergenic foods • Mom paid for IgG blood tests via alternative health practitioner 2 yrs ago: egg specific IgG blood test negative – mom gave egg at home & girl had anaphylaxis • Currently: egg specific IgE negative • Approach?
  • 4. 5/26/2014 4 What does “food allergy” really mean? • ADVERSE REACTION to food=any abnormal reaction, due to: • I) TOXIC – Bacterial enterotoxins – Other food poisonings • II) NON-TOXIC – 1. “Food Allergy” = Immune mediated – 2. Food Intolerance = Non-immune Johansson S, EAACI, Allergy 2001; 56:813-24 Definitions, cont’d • 1. “Food Allergy” – IgE mediated (e.g. anaphylaxis, oral allergy syndrome) – Mixed IgE/non-IgE (e.g. eosinophilic esophagitis) – Non-IgE (e.g. Protein induced enterocolitis) • 2. Food Intolerance – Enzyme deficiency (e.g. lactase deficiency) – Pharmacologic sensitivity (e.g. caffeine) – Psychologic (e.g. food aversion) Johansson S, EAACI, Allergy 2001; 56:813-24
  • 5. 5/26/2014 5 IgE mediated Food Allergy: Suspected foods • Majority of IgE mediated reactions due to these foods: – Cow’s milk* – Egg* – Peanut* & Tree nuts – Sesame seed – Fish & Shellfish – (Soy) – (Wheat) Predictive values for skin tests • Positive predictive value low unless recent and clear history – “Asymptomatic sensitization” • Negative predictive value high • i.e.) negative results more useful than positive ones – Guidelines for the Diagnosis and Management of Food Allergy in the U.S. J Allergy Clin Immunol 2010; 126:S1-S58
  • 6. 5/26/2014 6 Predictive values for serum specific IgE • Positive predictive value low unless recent and clear history – “Asymptomatic sensitization” • Negative predictive value high • i.e.) negative results more useful than positive ones – Guidelines for the Diagnosis and Management of Food Allergy in the U.S. J Allergy Clin Immunol 2010; 126:S1-S58 PREDICTIVE VALUES FOR COMMON FOODS, Specific IgE blood tests Sampson HA, J Allerg Clin Immunol, 2004;113:805-19
  • 7. 5/26/2014 7 Oral Food Challenges • The gold standard in the allergist’s evidence based approach • For ruling out food allergy • For the follow-up of food allergy (?outgrowing) – Generally done when specific IgE levels fall to a level at which ~50% tolerate the food Sicherer SH & Bock SA. J Allergy Clin Immunol 2006;117:1419-22 • …positive test results for food-specific IgG are to be expected in normal, healthy adults and children • The CSACI strongly discourages the practice of food specific IgG testing for the purposes of identifying or predicting adverse reactions to food
  • 8. 5/26/2014 8 Objectives • Discuss: How to diagnose food allergies • Examine: How to manage non-acute food allergies • Review: Update on the prevention of food allergy Management of allergic conditions • Allergen avoidance • Medical management • Immunotherapy (where indicated)
  • 9. 5/26/2014 9 Egg allergy: eat baked goods regularly? • 1. May result in outgrowing egg allergy earlier – Via tolerance induction • 2. Possible improved quality of life • 3. Often, children are already eating occasionally, and message is then to increase to daily ingestion Dietary baked egg accelerates resolution of egg allergy in children • Prospective, 79 subjects, baked oral challenges, 37.8 month F-up, usual recipe, control • Egg tolerance median 50.0 vs 78.7 mo (p<.0001) • IgE↓ , IgG4↑ Leonard SA, Sampson, Sicherer et al. JACI 2012
  • 10. 5/26/2014 10 Egg allergic children not currently eating baked goods • Recent evidence suggests 70-80% of children with egg allergy tolerate baked goods • Difficult to predict the 20-30% who will react if not currently eating already – History, skin tests, and specific IgE blood tests do not reliably correlate with chance of reacting if not currently eating • Decision to offer oral challenge individualized 2013 Bartnikas L, Schneider L et al, JACI IP Intramuscular flu vaccine can be safely given to those with egg allergy • Canadian multi-centre study: – 367 patients recruited (132 severe egg allergy) – Analyzed with other studies, total 4172 patients (513 severe egg allergy) – None had anaphylaxis Des Roches A et al. J Allergy Clin Immunol. 2012 Nov;130(5):1213-1216
  • 11. 5/26/2014 11 Case: 6 year old boy • History of peanut and tree nut allergy • Has been carrying an Epipen Junior since 2 yrs of age • Child is now 21 kg • MD writes prescription for Epipen Regular 0.3mg • Pharmacist faxes back with message that monograph for Epipen says to use 0.3mg only for 30kg or more • What to do next? Only 2 doses of epinephrine autoinjectors • Balance of efficacy & safety • 0.3mg (Epipen or Allerject) – 25kg children – 20kg children at higher risk (asthma) • 0.15mg (“Junior”) – 10-25kg children – Often prescribed for “less than 10kg” due to lack of alternatives Sicherer SH and Simons FER. Pediatrics 2007;199(3), 638-46
  • 12. 5/26/2014 12 • Randomized, controlled crossover trial • Primary outcome of ‘desensitization’ at 6 months (passed oral challenge) – 62% in active group, 0% in control group • 84% of the active group tolerated 800mg peanut protein daily (~ 5 peanuts) • Side effects mild in majority Oral food immunotherapy not ready for clinical use yet • Safety: anaphylaxis risk variable in studies, ?eosinophilic esophagitis risk • Efficacy: short term ‘desensitization’ versus long term ‘tolerance’? – No standard protocol – Some data for return of cow’s milk allergy after therapy • Cost effectiveness? • More studies needed Greenhawt MJ. Lancet 2014;383:1272-4
  • 13. 5/26/2014 13 Objectives • Discuss: How to diagnose food allergies • Examine: How to manage non-acute food allergies • Review: Update on the prevention of food allergy Case: 3 month old boy • History of atopic dermatitis • 5 yo brother with severe anaphylaxis to peanut, atopic dermatitis, severe asthma • Mom asks you… – Should I introduce peanut to Billy? – If yes, then…Why? • When? Where? How? – “He could get anaphylaxis the first time” • Am I putting Mike in danger?
  • 14. 5/26/2014 14 CPS Position Statement Dec 2, 2013 • Chan ES, Cummings C. Dietary exposures and allergy prevention in high-risk infants. Paediatr Child Health 2013;18(10):545-9 – www.cps.ca/documents/position/dietary- exposures-and-allergy-prevention-in-high-risk- infants • Joint statement of the CPS and the CSACI (Canadian Society of Allergy & Clinical Immunology) Canadian Family Physician, April 2014 issue
  • 15. 5/26/2014 15 Defining risk • An infant at high risk for developing allergy usually has – a first degree relative (at least one parent or sibling) with an allergic condition such as atopic dermatitis, food allergy, asthma, or allergic rhinitis – While recommendations are intended for high-risk infants, some of the studies cited included infants from the general population not considered high risk CPS Position Statement Recommendations • 1. Do not restrict maternal diet during pregnancy or lactation • 2. Breastfeed exclusively for the first six months of life • 3. Choose a hydrolyzed cow’s milk based formula for mothers who cannot or choose not to breastfeed – Extensively hydrolyzed casein likely more effective than partially hydrolyzed whey
  • 16. 5/26/2014 16 CPS Position Statement Recommendations • 4. Do not delay the introduction of any specific solid food beyond six months of age – Includes non-choking forms of peanut, egg, fish, etc – Delay does not prevent and may increase risk of food allergy • 5. More research is needed on inducing tolerance via early introduction between 4 to 6 months of age CPS Position Statement Recommendations • 6. Once introduced, regularly ingest the food (e.g. several times/week) to maintain tolerance – Routine skin or specific IgE blood testing before a first ingestion is discouraged due to the high risk of potentially confusing false-positive results
  • 17. 5/26/2014 17 Lack G. J Allergy Clin Immunol 2012; 129:1187-97 Clinical Teaching Pearls #1 • DIAGNOSIS – History is the most important “test” – Skin prick or specific IgE testing is susceptible to false positive results unless history of recent immediate reaction – Food-specific IgG testing to diagnose a food allergy is inappropriate, not evidence based, & strongly discouraged
  • 18. 5/26/2014 18 Clinical Teaching Pearl #2 • NON-ACUTE MANAGEMENT – Eating baked goods with egg may help with outgrowing egg allergy faster – Intramuscular flu vaccine is safe for egg allergy – Switch from the 0.15mg (“Junior”) epinephrine auto-injector dose to the 0.3mg (“Adult”) dose when a child reaches 20-25kg weight – Oral immunotherapy to food is not ready for clinical use Clinical Teaching Pearls #3 • PREVENTION – Do not delay introduction of any solid food beyond 6 months of age – Once introduced, eat regularly (e.g. several times/week)

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