Confirmation of triggers for anaphylaxis

References:

Simons FER. Anaphylaxis: recent advances in assessment and treatment. J Allergy Clin Immunol. 2009;124(4):625-636.
Sampson HA, Munoz-Furlong A, Campbell RL, et al. Second symposium on the definition and management of anaphylaxis: summary report—Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin Immunol. 2006;117(2):391-397.
EpiPen [patient insert]. Napa, CA: Dey Pharma LP; April 2008.
Gonzales-Perez A, Aponte Z, Vidaurre CF, et al. Anaphylaxis epidemiology in patients with and patients without asthma: a United Kingdom database review. J Allergy Clin Immunol. 2010;125(5):1098-1104.
Simons FER. Anaphylaxis. J Allergy Clin Immunol. 2010;125(suppl 2):S161-S181.
Ben-Shoshan M, Clarke AE. Anaphylaxis: past, present and future. Allergy. 2011;66(1):1-14.
Sicherer SH, Simons FE. Quandaries in prescribing an emergency action plan and self-injectable epinephrine for first-aid management of anaphylaxis in the community. J Allergy Clin Immunol. 2005;115(3):575-583.
Lieberman P, Kemp SF, Oppenheimer J, Lang DM, Bernstein IL, Nicklas RA. J Allergy Clin Immunol. 2005;115(suppl 2):S483-S523.
Lieberman P, Nicklas RA, Oppenheimer J, et al. The diagnosis and management of anaphylaxis practice parameter:2010 update. J Allergy Clin Immunol. 2010; 126(3):477-480.e1-e42.
Moffitt JE, Golden DBK, Reisman RE, et al. Stinging insect hypersensitivity: a practice parameter update. J Allergy Clin Immunol. 2004;114(4):869-886.
Banerji A, Rudders SA, Corel B, et al. Repeat epinephrine treatments for food-related allergic reactions that present to the emergency department. Allergy Asthma Proc. 2010; 31(4):308-316.
Chapman JA, Bernstein IL, Lee RE, et al. Food allergy: a practice parameter. Ann Allergy Asthma Immunol. 2006;96(3 Suppl 2):S1-S68.
Simons FER, Frew AJ, Ansotegui IJ, et al. Risk assessment in anaphylaxis: current and future approaches. J Allergy Clin Immunol. 2007;120:S2-S24.

Confirmation of triggers for anaphylaxis

In patients who have experienced anaphylaxis, it is important to confirm the trigger or triggers. A detailed history of prior exposures and resulting reactions can identify specific triggers that should be avoided in order to prevent recurrences of anaphylaxis.⁵

Determining the nature of the symptoms during previous anaphylactic reactions is also important. Essential questions to ask your patient include^8,9:

Were there cutaneous manifestations, specifically pruritus, flushing, urticaria, or angioedema?
Was there any sign of airway obstruction involving either the upper or lower airway?
Were there gastrointestinal symptoms (ie, nausea, vomiting, or diarrhea)?
Were syncope or presyncopal symptoms present?

In addition to the patient’s history, several tests are available to help identify triggers of anaphylaxis including skin tests, in vitro tests, and challenge tests.^5,8,9 These tests are described in Table 4.

Table 4. Tests which confirm anaphylactic triggers
Skin tests Determine the presence of IgE antibodies and identify anaphylactic reactions triggered by food, medications, and stinging insects^8,9 Skin tests are performed at least 3 to 4 weeks after an anaphylactic reaction^1,5 In the case of a skin prick/puncture test, a positive result is indicated by a mean wheal diameter of 3 mm or greater¹² *In vitro* tests Determine the presence of allergen-specific IgE levels in the serum and identify anaphylactic reactions triggered by food, stinging insect venom, medications, and natural rubber latex^12,13 In vitro tests are considered less sensitive than skin tests^8,9,12 ImmunoCAP is an example of a quantitative in vitro test, which correlates IgE levels with clinical reactivity and has predictive values for positive or negative results¹ Challenge tests Physician-monitored challenge tests may be used if skin or in vitro test results are inconclusive^8,9 Challenge tests help predict the clinical reactivity to anaphylaxis triggered by food and medication¹³ Challenge tests are time consuming, costly, and risky, and should be conducted only in well-equipped health care facilities staffed by health care professionals who are trained and experienced in selecting appropriate patients for these tests, performing challenges, and diagnosing and treating anaphylaxis^1,13

Table 4. Tests which confirm anaphylactic triggers

Skin tests

Determine the presence of IgE antibodies and identify anaphylactic reactions triggered by food, medications, and stinging insects^8,9
Skin tests are performed at least 3 to 4 weeks after an anaphylactic reaction^1,5
In the case of a skin prick/puncture test, a positive result is indicated by a mean wheal diameter of 3 mm or greater¹²

In vitro tests

Determine the presence of allergen-specific IgE levels in the serum and identify anaphylactic reactions triggered by food, stinging insect venom, medications, and natural rubber latex^12,13
In vitro tests are considered less sensitive than skin tests^8,9,12
ImmunoCAP is an example of a quantitative in vitro test, which correlates IgE levels with clinical reactivity and has predictive values for positive or negative results¹

Challenge tests

Physician-monitored challenge tests may be used if skin or in vitro test results are inconclusive^8,9
Challenge tests help predict the clinical reactivity to anaphylaxis triggered by food and medication¹³
Challenge tests are time consuming, costly, and risky, and should be conducted only in well-equipped health care facilities staffed by health care professionals who are trained and experienced in selecting appropriate patients for these tests, performing challenges, and diagnosing and treating anaphylaxis^1,13