Greater disease severity in adults with paediatric-onset versus adult-onset bronchiectasis: a multicenter EMBARC registry study.

Background: Young adults with paediatric- onset bronchiectasis (POBE) represent a minority of bronchiectasis patients and are poorly characterized. We aimed to compare the characteristics and severity of adults with POBE to adult-onset bronchiectasis (AOBE).

Methods: Data from four EMBARC (European Bronchiectasis Registry) centers were analyzed. POBE was defined as patient-reported symptom onset before 18 years, while AOBE was defined as symptom onset at or after 18 years. We compared POBE to AOBE and used multivariable models to identify factors associated with disease severity, including lung function, Pseudomonas aeruginosa infection, exacerbations, and hospitalizations.

Results: Among 1422 patients, 249 (17.5%) had POBE (mean onset age: 6.5 years), and 1173 had AOBE (mean onset age: 55.4 years). POBE patients were younger at enrollment (50.3 versus 66 years), had longer disease duration (43.3 versus 10.8 years), worse lung function (FEV1% predicted: 70.8 versus 84.2), greater radiological extent (Reiff index: 6.0 versus 4.4), higher bacterial infection rates (72.3% versus 54.6%), and more exacerbations (median: 2 versus 1 per year) compared to AOBE (p<0.001 across all comparisons). Symptom duration was independently associated with P. aeruginosa infection, hospitalization, exacerbations, and reduced FEV1%. Congenital etiologies, such as primary ciliary dyskinesia and primary immune deficiencies, further contributed to disease severity.

Conclusions: Adults with POBE exhibit greater disease severity than those with AOBE, likely due to prolonged symptom duration and congenital aetiologies. Conventional bronchiectasis severity scores may underestimate severity in young people with POBE. Optimized care, including structured transition to adult care, may mitigate progression in POBE patients.