Diagnosis of anaphylaxis at presentation (Table 2)
We included three studies with 516 participants about the immediate diagnosis of people presenting with anaphylaxis (as opposed to retrospectively confirming a suspected diagnosis). Other approaches such as serum tryptase are not summarised here because they help with subsequent confirmation rather than immediate diagnosis.
The National Institute of Allergy and Infectious Disease and the Food Allergy and Anaphylaxis Network (NIAID/FAAN) criteria aim to define anaphylaxis for research and clinical purposes. It is unclear whether these criteria help to diagnose anaphylaxis because the certainty of evidence is very low, but there are positive trends (supplement S4a and Table 2).
Sensitivity is an important indicator of the accuracy of criteria for the immediate diagnosis of anaphylaxis. The NIAID/FAAN criteria may be highly sensitive, but less specific. There were three eligible studies in adults and children. One consecutive case series found that the NIAID/FAAN criteria had sensitivity of 0.95 (95% confidence interval (CI) 0.85 to 0.99) and specificity of 0.71 (95% CI 0.61 to 0.79, very low certainty).11Loprinzi Brauer CE, Motosue MS, Li JT, Hagan JB, Bellolio MF, Lee S, Campbell RL. Prospective validation of the NIAID/FAAN criteria for emergency department diagnosis of anaphylaxis. J Allergy Clin Immunol Pract 2016;4(6):1220-1226. A case-control study found sensitivity of 97% (95% CI 89% to 99%) and specificity of 82% (95% CI 76% to 88%, very low certainty).22Campbell RL, Hagan JB, Manivannan V, Decker WW, Kanthala AR, Bellolio MF, Smith VD, Li JT. Evaluation of national institute of allergy and infectious diseases/food allergy and anaphylaxis network criteria for the diagnosis of anaphylaxis in emergency department patients. J Allergy Clin Immunol 2012;129(3):748-52. Another case control study found sensitivity of 0.67 (95% CI 0.46 to 0.75) and specificity of 0.70 (0.59 to 0.80, very low certainty)33Erlewyn-Lajeunesse M, Dymond S, Slade I, Mansfield HL, Fish R, Jones O, Benger JR. Diagnostic utility of two case definitions for anaphylaxis: a comparison using a retrospective case notes analysis in the UK. Drug Saf 2010;33(1):57-64.
The Brighton Collaboration case definition is designed for standardising adverse events following immunisations. It includes many different adverse effects to vaccines, not solely anaphylaxis. It is unclear whether this definition helps to diagnose anaphylaxis because the certainty of evidence is very low (supplement S4b). One case control study found that this definition had sensitivity of 0.68 (95% CI 0.54 to 0.80) and specificity of 0.91 (95% CI 0.80 to 0.96) in children and adults (very low certainty).44Erlewyn-Lajeunesse M, Dymond S, Slade I, Mansfield HL, Fish R, Jones O, Benger JR. Diagnostic utility of two case definitions for anaphylaxis: a comparison using a retrospective case notes analysis in the UK. Drug Saf 2010;33(1):57-64.