INTRODUCTION: Exacerbations in preschool wheezers increase the risk of impaired lung function and asthma persistence at school age. Bronchial remodelling-based latent classes identify severe preschool wheezers at increased risk of frequent exacerbations (>3) but failed to distinguish those without exacerbation from those with low exacerbations rate (1-2 exacerbations) in the year following bronchoscopy. We thus aimed to identify further independent factors associated with no, low or high exacerbation rates. METHODS: In this post-hoc analysis, 80 severe preschool wheezers from the “P’tit Asthme” and “RESPIRE” studies were divided into 3 groups: No-Ex (0 exacerbation in the year following the bronchoscopy, n=20), Low-Ex (1-2 exacerbations, n=27) and High-Ex (≥3 exacerbations, n=33). Associations between variables and groups were assessed using multinomial logistic regressions. RESULTS: Atopic dermatitis, age at the first wheezing episode, Haemophilus and Streptococcus genera in the bronchoalveolar lavage fluid (BALF), bronchial smooth muscle (BSM) area, reticular basement membrane (RBM) thickness and RBM-BSM distance were all significantly different between No-Ex and/or Low-Ex and/or High-Ex. However, only atopic dermatitis, age at first episode of wheezing, Haemophilus genus in the BALF, RBM-BSM distance and BSM area were significantly and independently associated with exacerbation frequency. Among them, the BSM area was the sole parameter independently associated with each group. CONCLUSION: While atopic dermatitis, age at the first episode of wheezing, Haemophilus in BALF, RBM-BSM distance and BSM area appeared to be relevant independent parameters associated with exacerbation susceptibility in severe preschool wheezers, only the increased BSM area discriminated between each of the three-exacerbation frequency-based groups.

Background: Oral immunotherapy (OIT) seems to be a promising treatment for hazelnut allergy but the available data is limited. Our objective was to evaluate the proportion of patients desensitised after hazelnut OIT, as well as to evaluate the proportion and type of adverse events (AEs) occurring during OIT and to identify clinical and biological factors predictive of OIT success. Methods: Single-center retrospective study, including pediatrics patients. Oral food challenge (OFC) was performed before and after OIT. For each patient, we collected clinical data and the level of hazelnut IgEs f17, nCor a 9, rCor a 14, at the time of the 2 OFCs. Results: After 12 months of OIT, 52.2% of children were desensitized. Those not desensitized increased their reactogenic dose by 6-fold. One-third presented an AE, mostly non-serious. They were significantly more likely to be desensitized if the levels of hazelnut IgE f17, nCor a 9, and rCor a 14 were initially low. Predictive thresholds of 16.3 kUA/L for hazelnut IgE f17 (p=0.0066) and 4.13 kUA/L for rCor a 14 (p=0.0447) were calculated with an NPV of 85%. Conclusion: Hazelnut OIT is effective in inducing tolerance in 52.2% of children. Children with lower specific IgEs (hazelnut f17, nCor a 9 and rCor a 14) were significantly more likely to achieve desensitization after 12 months of OIT. Predictive thresholds for f17 and rCor a 14 were defined above which the risks of failure of OIT are high.