Does the nature of adult difficult asthma differ by age of onset? Findings from WATCH.

Background: Phenotypic differences between early-onset (EODA) and adult-onset (AODA) difficult asthma in adulthood are not well described. Aim: To characterise EODA and AODA in difficult asthma. Methods: The Wessex AsThma CoHort of difficult asthma (WATCH) is a longitudinal study at University Hospital Southampton (UHS) UK set up in 2015. To date, 380 patients are enrolled from the UHS tertiary difficult asthma clinic. Clinical features of EODA (age ≤18 yrs) and AODA (age >18 yrs) are presented here. Results: Of 368 patients with available data, 51.6% had EODA and 48.4% AODA (median age of onset 4.0 yrs v 40.5 yrs respectively (p EODA had a greater proportion with eczema ever (30.6% v 10.3% p Functional comorbidities were more prevalent in EODA; dysfunctional breathing (61.9% v 45.9% p=0.003), depression (42.9% v 32.1% p=0.045) and anxiety (40.0% v 24.4% p=0.003). Rhinitis, GORD and obesity did not differ, but COPD (14.3% v 3.7% p EODA had more ICU admissions in the past year (33.0% v 21.1% p=0.011) and intubation ever for asthma (17.1% v 9.7% p=0.040). Conclusion: EODA is commoner in females and associated with more atopy, functional comorbidity, biologic therapy and healthcare need. AODA is commoner in males associated with smoking and comorbid lung disease.