Immunoglobulin E-mediated immediate allergic reactions to dipyrone: value of basophil activation test in the identification of patients

Abstract

Background: Pyrazolones are a major cause of immediate IgE-mediated reactions to drugs in many countries.

Objective: The aim of the study was to evaluate a group of patients with this type of reaction by basophil activation test (BAT), focusing on the influence on positivity of the time between the reaction and this study.

Methods: The study included 51 patients with selective immediate allergic reactions to pyrazolones and 56 controls. Patients were defined by skin testing or a drug provocation test and BATs with pyrazolones were carried out in all cases. Patients who were BAT positive were followed-up for 30 months to establish the rate of decline in positive tests.

Results: BAT was positive in 28 (54.9%) cases. BAT sensitivity was higher in those who were skin-test positive (85.7%) compared with those who were skin-test negative (33.3%). The time between the initial reaction and this study was significantly shorter in those who were skin-test positive (P=0.005) and those who were BAT positive (P=0.017). Follow-up of the BAT-positive patients showed a decrease over time, with 60% of these patients becoming negative after 6 months.

Conclusions: BAT is a useful complement to skin testing for the evaluation of immediate allergic reactions to pyrazolones. Although not optimal, BAT sensitivity was also positive in patients with a negative skin test and it is a reasonable alternative in patients with severe reactions who may develop symptoms after skin testing. The time of performance of the test is critical to obtain a positive response.