Referral to immunologist/allergist after anaphylaxis

Some suggested US referral criteria to an immunologist (allergist) include (1):

• with respect to anaphylaxis:
  • individuals with a severe allergic reaction (anaphylaxis) without an obvious or previously defined trigger
    • after a severe allergic reaction without a known cause, a trigger should be identified if at all possible. An allergist-immunologist is the most appropriate medical professional to perform this evaluation, which might include skin testing, in vitro tests, and challenges when indicated (including with exercise, see below). Future avoidance of the identified triggers should prevent subsequent anaphylactic episodes.
  • persons with anaphylaxis attributed to food
    • food allergy is the most common cause of anaphylaxis outside of the hospital setting .Allergist-immunologists use diagnostic modalities to confirm the trigger and use their specific training and clinical experience to educate patients regarding avoidance and immediate management to prevent potentially
  • exercise-induced anaphylaxis and food-dependent exercise-induced anaphylaxis
    • after an anaphylactic reaction that appears to have a significant relationship to exercise, it is crucial to be certain whether exercise is the cause and to determine whether a food might be involved
  • drug-induced anaphylaxis
    • allergist-immunologists use diagnostic agents to confirm the drug responsible for the reaction, if these agents are available
  • UK guidance suggests referral, in general, for all patients after initial episode (2)
• with respect to food allergy:
  • persons who have experienced allergic symptoms (urticaria, angioedema, itch, wheezing, and gastrointestinal responses) in association with food exposure
  • persons who experience an itchy mouth from raw fruits and vegetables
• with respect to insect hypersensitivity:
  • consider referral of patients with systemic reactions suspected or possibly caused by insect stings for accurate identification of specific allergen and consideration for venom immunotherapy
  • consider referral of patients with systemic reactions suspected or possibly caused by biting insects for accurate identification of specific allergen

Notes:

• UK guidance suggests that (2,3):
  • a referral to an immunologist or allergist is needed, in general, for all people with history of angioedema/anaphylaxis
    • note though that in people on angiotensin-converting enzyme (ACE) inhibitors the clinician should stop medication and only refer if angio-oedema is persistent or they have recurrent episodes (2)
  • NICE state (3):
    • after emergency treatment for suspected anaphylaxis, offer people a referral to a specialist allergy service
      
      
  • indications for prescribing an adrenaline auto-injector device:
    • adrenaline auto-injector devices are indicated for people with a severe allergic reaction involving the airway and/or hypotension
    • the decision to prescribe an adrenaline auto-injector is usually undertaken by an immunologist or an allergist, although local services may also be provided by a GP with specialist training in allergy management in some areas
    • NICE state that (3):
      • after emergency treatment for suspected anaphylaxis, offer people (or, as appropriate, their parent and/or carer) an appropriate adrenaline injector as an interim measure before the specialist allergy service appointment
    • seek specialist advice from the immunologist or allergist regarding local recommendations for interim management of these people
    • other groups who may be prescribed an adrenaline auto-injector include:
      • people whose reaction is triggered by an unavoidable allergen
      • people with a localised reaction (not involving the airway) in a person who is considered high risk (e.g. people with asthma, reaction to trace allergen only, likely repeated exposure to allergen, or lack of access to emergency care). Comorbidities may alter the risk to benefit ratio.

Reference:

• (1) National Guideline Clearinghouse (28/1/2008).Consultation and referral guidelines citing the evidence: how the allergist-immunologist can help.
• (2) CKS (2007). Angio-oedema and anaphylaxis.
• (3) NICE (December 2011). Anaphylaxis: assessment to confirm an anaphylactic episode and the decision to refer after emergency treatment for a suspected anaphylactic episode.