The use of Basophil Activation Test (BAT) for diagnosing IgE mediated allergy and monitorising immunotherapy response has increased over last years. BAT has gained especial interest when diagnosis is complex, as in immediate drug hypersensitivity reactions (IDHR) which can produce over/under-diagnosis with consequences for patient safety. In vivo tests, skin tests (ST) and drug provocation tests (DPT), for IDHR diagnosis can have a suboptimal sensitivity or be potentially risky. BAT is a functional test that could help identify the responsible drug or safe alternatives, especially in
cases in which in vivo tests can produce equivocal results or DPTs are not recommended. BAT is used for the most frequent drugs, for many others for which no other diagnostic test is available, and more recently, chemotherapeutic and biological agents. Results indicate a good specificity and variable sensitivity with controversial results in some cases, being DRAFT complementary to ST. Moreover, it is being considered for monitoring drug desensitisation to evaluate its prognostic value to predict reactions. Although BAT use is widening, there are still many questions to be answered regarding its use in IDHRs: its utility for some drugs, useful basophil markers, and several tips to take into account when performing BAT for evaluating IDHRs. All these could generate important confusion and could discourage users of this test. Therefore, it is necessary to develop specific guidelines and recommendations for the application of BAT specifically in IDHRs addressing all these gaps. We aim to: perform a survey to clinicians to check their impressions about BAT advantages/disadvantages to diagnoseIDHRs; and describe the conditions for overcoming the BAT limitations and include recommendations in a consensus document using the survey together with data from the literature and group’s own experience.

Chair: Cristobalina Mayorga
Secretary: Didier Ebo