Supplementary Material for: Basophil activation test (BAT) is inferior to provocation test in diagnosing aspirin hypersensitivity

Introduction Diagnostic of aspirin (ASA) hypersensitivity is largely based on provocation tests. However they have significant limitations including influence of medications, necessity of hospitalization and safety issues. Basophil activation test (BAT) seems to be a promising in vitro alternative. It has already proven to be a useful tool for diagnosing IgE-mediated allergy to certain food and airborne allergens as well as insects venoms. The aim of the study was to assess performance of BAT in diagnosing aspirin hypersensitivity in comparison with current golden standard (oral provocation test; OPT). Methods The study group comprised 148 adult patients with suspicion of aspirin hypersensitivity, including 51 (36%) with chronic urticaria, 73 (51%) with asthma and 55 (39%) with chronic sinusitis. The control group were 10 healthy adult patients who used NSAIDs during preceding year with good tolerance. BAT with ASA was conducted in all the participants. Additionally, in the study group OPT was performed with cumulative dose of 1000 mg of ASA. Results Out of 148 study group participants, 114 underwent BAT and ASA provocation with conclusive results acquired in both tests. In this group the threshold for positive BAT was 4.9%. Sensitivity and specificity of BAT were found to be 55.9% and 75% respectively, with positive predictive value of 77% and negative predictive value of 54%. The highest sensitivity (78%) was found in subgroup patients with chronic urticaria while specificity was highest in the subgroup with chronic respiratory diseases (87%). Conclusion Despite significant advantages of BAT such as safety, no influence of drugs and objectivity, its performance makes it inferior to current standard in ASA hypersensitivity.