Background: Anaphylaxis is the more severe form of immediate hypersensitivity. It can be life-threatening and therefore requires fast and appropriate medical management. After a first hypersensitivity phase, a recurrence of symptoms without an elicitor re-exposure may occur, called a biphasic reaction. The aim of this study was to identify biological and clinical predictors of biphasic reactions in patients with anaphylaxis. Methods: We retrospectively compared patients with monophasic anaphylaxis to those with biphasic anaphylaxis from an allergology day hospital in a French university hospital between January 2017 and May 2020. Results: Among the 237 patients, the rate of biphasic reactions was 5.5% (n = 13). The odds of a biphasic reaction was increased with asthma (p = 0.021; odds ratio = 4 [95% confidence interval 1.05-14.81]) and loss of consciousness during anaphylaxis (p = 0.008) as compared with monophasic anaphylaxis. Basal tryptase levels were significantly higher with biphasic than monophasic anaphylaxis (p = 0.009). Conclusions: Asthma and unconsciousness during the first phase of anaphylaxis could be associated with a biphasic reaction . Elevated basal tryptase was linked to biphasic reactions, which should be further explored.

Background Patients with severe asthma may present with characteristics representing overlapping phenotypes, making them eligible for more than one class of biologic. Our aim was to describe the profile of severe adult asthma patients eligible for both anti-IgE and anti-IL5/5R and to compare the effectiveness of both classes of treatment in real life. Methods This was a prospective cohort study that included adult severe asthma patients from 22 countries enrolled into the International Severe Asthma registry (ISAR) who were eligible for both anti-IgE and anti-IL5/5R. The effectiveness of anti-IgE and anti-IL5/5R was compared in a 1:1 matched cohort. Exacerbation rate was the primary effectiveness endpoint. Secondary endpoints included long-term-oral corticosteroid (LTOCS) use, asthma-related emergency room (ER) attendance and hospital admissions. Results In the matched analysis (n=350/group), the mean annualized exacerbation rate decreased by 47.1% in the anti-IL5/5R group and 38.7% in the anti-IgE group. Patients treated with anti-IL5/5R were less likely to experience a future exacerbation (adjusted IRR 0.76; 95% CI 0.64, 0.89; p<0.001) and experienced a greater reduction in mean LTOCS dose than those treated with anti-IgE (37.44% vs 20.55% reduction; p=0.023).) There was some evidence to suggest that patients treated with anti-IL5/5R experienced fewer asthma-related hospitalizations (IRR 0.64; 95% CI 0.38, 1.08), but not ER visits (IRR 0.94, 95% CI 0.61, 1.43). Conclusions In real life, both anti-IgE and anti-IL5/5R improve asthma outcomes in patients eligible for both biologic classes, however anti-IL5/5R was superior in terms of reducing asthma exacerbations and LTOCS use.