Introduction
The burden of food allergy (FA) remains a significant public health concern. There is ample evidence for the negative impact that FA can have on the quality of life of patients and their families, on the breadth and quality of social interactions, on the performance at school or work and on overall psychological well-being [1-3]. This is aggravated by the financial strain that FAs impose on families and individuals through the cost of allergen-free food, direct and indirect medical expenses, and missed work or school days [4].
A recently published study documents a continued increase in the prevalence of FA in Europe. It estimates lifetime and point prevalence of self-reported FA to be 20% and 13%, respectively [5]. Considering both a clinical diagnosis of food allergy or a positive OFC, FAs have increased from 2.6% in the early 2000’s to 3.5% in the next decade [5]. Currently, FA confirmed by oral food challenge (OFC) worldwide is estimated at 4%[6]. This has resulted in a growing demand for appropriate FA diagnosis, driving health care professionals to employ a wide range of allergy tests. However, not all these diagnostic tests are equally useful or appropriate to reach an accurate diagnosis of FA and while the OFC remains the reference standard, it is a costly and time-consuming procedure that may lead to life-threatening anaphylaxis [7]. For a highly sensitive test, a negative result effectively rules out the diagnosis of FA; for a highly specific test, a positive result rules in a FA diagnosis. Deeper understanding of diagnostic test accuracy could reduce the need for OFC and guide clinical practice.
Determining the optimal diagnostic cut-offs in single studies that are generalisable to other clinical settings poses a significant challenge. By combining and analysing data from multiple studies, we can overcome the limitations of individual studies and gain a more comprehensive understanding of the diagnostic performance of tests. Meta-analyses allow us to synthesize findings from various sources, enhancing the reliability and generalizability of the results. Thus, they play a crucial role in guiding clinical decision-making and improving diagnostic accuracy.
The European Academy of Allergy and Clinical Immunology (EAACI) is updating their guidelines on both the diagnosis and management of FA [8, 9]. A systematic review (SR) of index tests is the most reliable form of evidence in the diagnostic field and enables clinicians and other healthcare professionals to make well-informed decisions [10, 11]. To inform the EAACI guidelines on FA diagnosis, we undertook a SR and meta-analysis (meta-analyses) about the accuracy of index tests to support the diagnosis of IgE-mediated FA, following a previously registered and published protocol [12].
This SR addresses the question: What is the diagnostic accuracy measured by the sensitivity and specificity of any index test for IgE-mediated FA to any food compared with the reference standard OFC (in at least a subset of patients) or previous clear history of immediate reaction to the food and evidence of IgE sensitisation?