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Clinical food challenges 2007 EAACI Göteborg

Clinical food challenges 2007 EAACI Göteborg. Ulf Bengtsson Department of Respiratory Medicine and Allergology Sahlgrenska University Hospital Göteborg. Introduction.

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Clinical food challenges 2007 EAACI Göteborg

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  1. Clinical food challenges2007 EAACI Göteborg Ulf Bengtsson Department of Respiratory Medicine and Allergology Sahlgrenska University Hospital Göteborg Ulf Bengtsson

  2. Introduction • In many situations, the diagnosis of food allergy rests simply upon a history of an acute onset of typical symptoms, such as hives and wheezing, following the isolated ingestion of a suspected food, with conformatory positive IgE-tests. Ulf Bengtsson

  3. When is history and IgE-test enough? Ulf Bengtsson

  4. Ex. • A history of anaphylaxis and pos IgE-tests; here challenges normally are contraindicated! • Clear-cut objective symptoms with pos IgE-tests Ulf Bengtsson

  5. The diagnosis is more complicated in other situations: Ulf Bengtsson

  6. When multiple foods are implicated • In chronic diseases: asthma, atopic dermatitis • When reactions are not IgE-mediated (e.g. food related gastrointestinal symptoms) Ulf Bengtsson

  7. Elimination diets followed by physician-supervised oral challenges are critical in the identification and proper treatment of these disorders Ulf Bengtsson

  8. Basics for investigation History and IgE-tests Food challenges Elimination diets Ulf Bengtsson

  9. The aims of controlled food challenges are: Ulf Bengtsson

  10. To prove that a certain allergen plays a role for the individual symptoms Ulf Bengtsson

  11. To exclude food allergy in order to prevent the individual being subjected to unnecessary or even harmful elimination diets Ulf Bengtsson

  12. Challenge models Indication Labial challenge In high risk patients? In patients with pronounced fear of special foods? Screening method? Titration /stepwise increase of dose, Open, single blind or DBPCFC. A history of anaphylaxis Open challenges with normal portions The actual history is doubtful Blinded placebo controlled food challenges-normal portion Add a food back to the diet under safe conditions In subjective symptoms- gastrointestinal complaints, atopic eczema Food aversion, a psychological condition when a person has a reaction, caused by emotions associated with food. Ulf Bengtsson

  13. Labial food challenge (LFC) The method was described by F Rancé, G Datau, France, PAI 1997; 8: 41-4 Ulf Bengtsson

  14. Method • Inspect the face and the mouth cavity • Place the food inside of the lower lip during 2 minutes. • Observe for local or systemic reactions in the ensuing 30 minutes Ulf Bengtsson

  15. Method A positive test is: • development of a contiguous rash of the cheek and chin • oedema of the lip with conjunctivitis or rhinitis • systemic reaction Ulf Bengtsson

  16. Method • Negative labial food challenges are generally followed by open oral food challenges Ulf Bengtsson

  17. Is LFC an alternative to the other methods? • Sensitivity is poor • DBPCFC are required after negative LFC results • Further comparative anlyses of the LFC and oral challenges will better determine the value of LFC for exploration of cases of food allergy Ulf Bengtsson

  18. Possible indications • In high risk patients where food challenges are planned Ulf Bengtsson

  19. Possible indications • Before open challenges in patients with a history of pronounced fear of special foods Ulf Bengtsson

  20. LFC • Simple • Rapid to perform • Associated with a low risk of systemic reactions Ulf Bengtsson

  21. Open food challenges Indications: • Reactions which can be confirmed objectively Ulf Bengtsson

  22. Open food challenges • For practical reasons, an open challenge can be the first approach when the probability of a negative outcome is estimated to be very high Ulf Bengtsson

  23. In infants and children <3 years old, an open, physician- controlled challenge is often sufficient for suspected immediate type reactions. Open food challenges Ulf Bengtsson

  24. Open food challenges • For patients with pollen-related oral allergy syndrome (OAS) as their only symptom, an open challenge could be sufficient as regular procedure - due to difficulties in blinding fruits and vegetables concerning their allergenicity Ulf Bengtsson

  25. Open food challenges • Pollen-related oral allergy syndrome (OAS) Ulf Bengtsson

  26. Characteristics: Fresh food in relevant amount. Can be titrated Advantages: Easily performed. Negative test makes DBPCFC superfluous Disadvantages: Risk of false positive results Summary - open food challenges Ulf Bengtsson

  27. Single blind placebo- controlled food challenges • Double blind placebo-controlled food challenges (DBPCFC) Ulf Bengtsson

  28. DBPCFC Placebo challenges are indicated • when expected late phase clinical reaction or day-to-day-variations play a role Ulf Bengtsson

  29. DBPCFC • when subjective symptoms may play a role (such as gastrointestinal symptoms, headache or palpitations) Ulf Bengtsson

  30. DBPCFC • DBPCFC is the method of choice for scientific protocols. Ulf Bengtsson

  31. Characteristics: Dehydrated food Advantages: Can be titrated, commercially available Disadvantages: Many capsules, reactions in mouth and throat not diagnosed, food quality unknown DBPCFC with capsules or tablets Ulf Bengtsson

  32. DBPCFC with masked vehicle • Characteristics: Fresh food in relevant amount. Can be titrated and given via tube or masked vehicle • Advantages: Quantity of allergen. Reactions in mouth diagnosed. Normal route of administration. • Disadvantages:Resource-demanding, not standardized Ulf Bengtsson

  33. Confusing factors….. Ulf Bengtsson

  34. Confusing factors • Physical exercise • Drugs (acetylsalicylic acid, beta-blockers, angiotensine-converting enzyme), alcohol • Fat content • Hormonal factors • Psychologicol factors Ulf Bengtsson

  35. Food-dependent exercise-induced anaphylaxis • Food-dependent exercise-induced anaphylaxis is revealed by a chronological sequence in which food intake, followed by exercise, induces symptoms after a varying period. • When the food intake and the exercise are independent of each other, there are no symptoms. Ulf Bengtsson

  36. Food dependent exercise induced anaphylaxis • In food-dependent exercise-induced anaphylaxis (FDEIA) it is difficult to mimic all parameters in the challenge procedure Ulf Bengtsson

  37. Food dependent exercise induced anaphylaxis • In the challenge procedure it may be important to standardize exercise with and without the suspected food Ulf Bengtsson

  38. Interplay between food allergens, aspirin and exercise • Aspirin enhances the induction of IgE- allergic symptoms when combined with foods and exercise in patients with food-dependent exercise-induced anaphylaxis. • Harada S et al. Br J Dermatol 2001; 145: 336-9 Ulf Bengtsson

  39. Food challenges and fat content The fat content of a challenge vehicle may effect the reaction pattern experienced after allergen ingestion.Grimshaw KE et al. Clin Exp Allergy 2003; 33: 1581-5 van Odijk J, Bengtsson U. et al. Allergy 2005; 60: 602-5 Ulf Bengtsson

  40. Food challenges and fat content • If you have a low (normal) fat content you may have reactions to a smaller dose and earlier onset of symptoms • If you have a high fat content the reactions are delayed and more pronounced perhaps because more foods are eaten before the reactions occurs. Ulf Bengtsson

  41. Problems….. Ulf Bengtsson

  42. There are no general agreements about • The amount of foods to use • How to hide taste, smell and colour • Time between separate challenges • Increase of dose • How to deal with patients with a history of food intolerance after days or weeks of regular intake of suspected foods (delayed reactions) • False negative test Ulf Bengtsson

  43. General agreement • Patients with manifest, life-threatening symptoms or anaphylaxis should not be challenged Ulf Bengtsson

  44. However…….. Ulf Bengtsson

  45. DBPCFCs in children with a history of ana- phylaxis to foods: Are they necessary and safe?BJ Vlieg-Boerstra, Groningen, Netherlands, AAAAI San Diego 2007 • 22 children with a clear-cut history of anaphylaxis to foods were double blind challenged • 16 were DB positive, 5 were negative (23%) and 1 was questionable. Ulf Bengtsson

  46. So perhaps, in selected cases with a history of food related anaphylaxis, we should challenge to avoid unnessesary elimination diets Ulf Bengtsson

  47. Specific IgE and DBPCFC • Allergy tests on their own cannot be considered diagnostic when approximately 10% of DBPCFC, although positive, do not correlate with immunoglobuline E-mediated disease. Ulf Bengtsson

  48. A special problem in adults is patients with a history of IBS-like symptoms. The prevalence of IBS in the western world is 20%. >60% of these patients have a history of food related abdominal symptoms mainly because of unspecific visceral hypersensitivity. Ulf Bengtsson

  49. The prevalence of IBS in the western world is 20% • >60% of these patients have a history of food related gastrointestinal symptoms Ulf Bengtsson

  50. In recent years several papers have been published indicating a specific hypersensitivity in subgroups of IBS-patients despite lack of food specific IgE in skin or serum. Ulf Bengtsson

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