Factors associated with "Frequent Exacerbator" phenotype in children with bronchiectasis: The first report on children from the Australian Bronchiectasis Registry.

ABSTRACT

INTRODUCTION: In adults with bronchiectasis, multicentre data advanced the field including disease characterisation and derivation of phenotypes such as 'frequent exacerbator (FE)' (≥3 exacerbations/year). However, paediatric cohorts are largely limited to single centres and no scientifically derived phenotypes of paediatric bronchiectasis yet exists. Using paediatric data from the Australian Bronchiectasis Registry (ABR), we aimed to (a) describe the clinical characteristics and compare Indigenous with non-Indigenous children, and (b) determine if a FE phenotype can be identified and if so, its associated factors. METHODS: We retrieved data of children (aged <18-years) with radiologically confirmed bronchiectasis, enrolled between March 2016-March 2020. RESULTS: Across five sites, 540 children [288 Indigenous; median age = 8-years (IQR 6-11)] were included. Baseline characteristics revealed past infection/idiopathic was the commonest (70%) underlying aetiology, most had cylindrical bronchiectasis and normal spirometry. Indigenous children (vs. non-Indigenous) had significantly more environmental tobacco smoke exposure (84% vs 32%, p < 0.0001) and lower birth weight (2797 g vs 3260 g, p < 0.0001). FE phenotype present in 162 (30%) children, was associated with being younger (ORadjusted = 0.85, 95%CI 0.81-0.90), more recent diagnosis of bronchiectasis (ORadjusted = 0.67; 95%CI 0.60-0.75), recent hospitalization (ORadj = 4.51; 95%CI 2.45-8.54) and Pseudomonas aeruginosa (PsA) infection (ORadjusted = 2.43; 95%CI 1.01-5.78). The FE phenotype were less likely to be Indigenous (ORadjusted = 0.14; 95%CI 0.03-0.65). CONCLUSION: Even within a single country, the characteristics of children with bronchiectasis differ among cohorts. A paediatric FE phenotype exists and is characterised by being younger with a more recent diagnosis, PsA infection and previous hospitalization. Prospective data to consolidate our findings characterising childhood bronchiectasis phenotypes are required.