Diagnosis of Food Allergy: Epicutaneous Skin Tests, In Vitro Tests, and Oral Food Challenge

Food allergy is becoming an increasingly common diagnosis. Because of this increase in prevalence, it is imperative that physicians evaluating patients with possible adverse reactions to foods understand the currently available assays and how they should best be used to accurately diagnose the disease. Simple tests such as skin prick testing (SPT) and serum food-specific IgE testing are the most commonly used diagnostic tests to evaluate for IgE-mediated food reactions. However, these tests, which measure sensitization and not clinical allergy, are not without pitfalls, and their utility must be appreciated to avoid over- and underdiagnosis. Although the physician-supervised oral food challenge remains the gold standard for food allergy diagnosis, a careful medical history paired with SPT and serum food-specific IgE testing often can provide a reliable diagnosis. In this review, we examine the usefulness and pitfalls of SPT and serum food-specific IgE levels, as well as examine atopy patch testing and other emerging tests, such as component-resolved diagnostics and the basophil activation test. Finally, we describe the use of the double-blind, placebo-controlled oral food challenge as the current gold standard for food allergy diagnosis.