Diagnostic accuracy of specific IgE to components in diagnosing peanut allergy: a systematic review

Abstract

The diagnostic accuracy of skin prick test (SPT) and specific IgE (sIgE) to peanut extract in diagnosing peanut allergy is suboptimal. Recent studies have evaluated sIgE to peanut components as a possible new diagnostic tool. The aim of our review was to systematically search the literature to assess the diagnostic value of sIgE to peanut components in diagnosing peanut allergy. A literature search was performed in PubMed, Embase and the Cochrane Library. Results were subsequently screened for in- and exclusion criteria. The quality of eligible studies was assessed using a standardized quality assessment tool (QUADAS-2). Data on sensitivity, specificity, and positive and negative likelihood ratios were extracted or calculated for a descriptive analysis. Twenty-two studies were eligible, of which 21 studies in paediatric populations. Most studies reported on sIgE to peanut extract (15) and sIgE to Ara h 2 (12), followed by SPT (9) and sIgE to Ara h 1 (7). All studies were at risk of bias or caused applicability concerns on at least one item of the quality assessment tool. The best combination of diagnostic accuracy measures of all diagnostic tests was found for sIgE to Ara h 2. This finding was independent of geographical location. Compared to SPT and sIgE to peanut extract, sIgE to Ara h 2 was mainly superior in diagnosing peanut allergy in case of a positive test result. Worst diagnostic accuracy measures were found in general for sIgE to Ara h 8 and sIgE to Ara h 9. sIgE to Ara h 2 showed the best diagnostic accuracy of all diagnostic tests to diagnose peanut allergy. Compared to the currently used SPT and sIgE to peanut extract, sIgE to Ara h 2 was superior in diagnosing peanut allergy and should therefore replace these tests in daily clinical practice, especially in children.

Diagnostic Value of Antigen-Specific Immunoglobulin E Immunoassays against Ara h 2 and Ara h 8 Peanut Components in Child Food Allergy

“…We conclude that it cannot reasonably be retained as an accurate tool to discriminate peanut allergy from tolerance, consistent with previous reports [12,23,24,25]. At a cutoff of 0.35 kU/l, the Ara h 2 sIgE immunoassay was acceptable, with a Youden index of 0.94 and a PPV of 100%, in line with recent results [17,26,27,28]. Thus, Ara h 2 sIgE immunoassay should be the first biological test performed for the diagnosis of peanut allergy.…”

“…The involvement of PR-10 such as Ara h 8 in severe peanut reactions is still a topic of debate [16,17]. However, oral syndrome has commonly been reported with PR-10 and cross birch or hazelnut allergy [29].…”

“…Ara h 8, a so-called pathogenesis-related protein (PR-10), is associated with mild peanut-induced reactions and cross-reacts with other PR-10 such as birch pollen protein Bet v 1 [16]. The diagnostic value of these component sIgE immunoassays, and notably their role in the diagnostic strategy, requires more thorough investigation [17,18]. …”

Structural Biology of Peanut Allergens

“…However, in the case of birch pollen allergic patients, Ara h 8 is more significant due to its cross-reactivity with Bet v 1 (Mittag et al, 2004). Interestingly, isolated Ara h 8 sensitization was suggested as being associated with no or mild symptoms among peanutsensitized patients (Asarnoj et al, 2012;Glaumann et al, 2013;Klemans et al, 2014). However, severe reactions have been reported with Ara h 8 recognition by IgE.…”

“…However, severe reactions have been reported with Ara h 8 recognition by IgE. Also, it is important to note that reactivity to Ara h 8 and 9 are geographically dependent and the severity of the reaction in monosensitized patients to either of these cannot be predicted accurately (Glaumann et al, 2013; Similarity ( Klemans et al, 2014). Until recently, the function of Ara h 8 was completely unknown.…”