xRead - September 2022

Wise et al.

Page 70

There are some important similarities and differences between skin testing and sIgE testing that warrant discussion. First, studies have indicated that while patients are accepting of both in vitro and in vivo allergy testing, skin testing may be preferred because it allows for immediate feedback and visible results. 914 Second, neither skin or sIgE testing can definitively predict the severity of a patient’s sensitivity to an aeroallergen. Third, cross reacting allergens and poly-sensitizations can confound both skin and in vitro testing, leading to false-positive results. 915 In contrast to skin testing, sIgE tests use more extensively quality-controlled allergens and defined human serum controls. Whereas skin testing depends upon the clinician administering and interpreting the test, sIgE tests have coefficients of variation less than 15% in the College of American Pathologists diagnostic allergy proficiency survey, which is performed 3 times per year by all Clinical Immunology Laboratories licensed by the Clinical Laboratory Improvement Act of 1988. However, several reports have demonstrated poor agreement in results from testing the same sera by different commercially available assay systems. 916,917 As with skin testing, sIgE results should be interpreted within the context of the patient’s clinical history. One application of sIgE technology is multiallergen screens consisting of 10 to 15 allergens. In scenarios where a clinician wishes to either rule in or out allergy as a driving factor behind symptoms without subjecting patients to the time and cost of a full testing battery, sIgE screens are an option. Generally, either a negative or positive result is given. Screens testing for 10 to 12 allergens (ie, molds, regional pollens, cat, and mite) are positive in up to 95% of patients who would have tested positive on a larger battery. 912,918 Therefore, they are effective in identifying allergic patients. Conversely, if the test is negative, there is evidence that this reliably supports an absence of allergy. 910 A second application lies in the fact that levels of sIgE may correlate with severity of AR symptoms. 919-923 Given that patients with more severe symptoms have been shown to respond better to AIT than those with milder symptoms, sIgE may help in the selection of candidates for AIT and possibly predict the response. 919,924 Third, in polysensitized patients, it can be difficult to determine the most relevant allergen on SPT. In these situations, sIgE levels can help discriminate the most relevant allergen and guide AIT. 920 Studies have shown that sIgE testing has a sensitivity between 67% and 96% and specificity of between 80% and 100%. 793,822,835,925,926 Further, it has been demonstrated that sIgE shows excellent correlations with both NPT and SPT in the diagnosis of AR. 793,822,835,857,911 There is good evidence to show that sIgE is, in many ways, equivalent to SPT. 218,818,925 The decision to perform sIgE must be based upon a thorough history and physical examination to confirm the presence of allergy and guide therapy when necessary. It is important to note that while sIgE levels are a biomarker of allergic sensitization, this test alone cannot provide a definitive diagnosis of allergy due to the high rate of clinically irrelevant (false-positive) tests without an indicative clinical history. Based on the reviewed literature, sIgE testing is an acceptable alternative to skin testing and is safe to use in patients who are not candidates for skin testing (Table VIII.F.2). • Aggregate Grade of Evidence: B (Level 3b: 7 studies; Table VIII.F.2).

Author Manuscript Author Manuscript Author Manuscript Author Manuscript

Int Forum Allergy Rhinol . Author manuscript; available in PMC 2020 June 10.