Does Aspergillus fungal sensitisation define asthma severity in difficult asthma? Findings from WATCH

Abstract

Background: Fungal sensitisation is associated with asthma severity, but is not well described in difficult asthma. Aim: To assess the clinical characteristics of difficult asthma with Aspergillus fungal sensitisation in relation to asthma severity. Methods: Clinical characteristics of difficult asthma with Aspergillus fungal sensitisation, defined by positive Aspergillus skin test or serology, was assessed in the WATCH difficult asthma cohort. Results: 16.3% (80/490) had Aspergillus fungal sensitisation; 51.3% female, 48.8% male, with older mean ages (51y vs 61y). Median age of asthma diagnosis was 12.5 yrs, with disease duration of 34 yrs. Maintenance oral steroid use (48.8%) and mean number of acute courses in past year (3.0) were greater, whilst healthcare utilisation (20.3% ≥1 hospitalisation; 35.4% ≥1 ICU admission) and missed working days; p=0.25 were not significant. Poor asthma control was reflected by a mean ACQ-6 score 2.21, with significant difference in those with positive Aspergillus skin test; p=0.014. 28.2% had ABPA with 16.3% on itraconazole. Mean peripheral blood eosinophil count was 0.34; 44.1% being ≥0.3. Mean total IgE was raised; 684.2kU/L, with 26.3% on Omalizumab. There was greater airflow obstruction; FEV1 62.8%, FEV1/FVC 61.0%, FEF 25-75 35.9%, with mean FeNO 31.7 ppb. Conclusion: Aspergillus fungal sensitisation in difficult asthma was seen at an older age. Early-onset asthma with longer disease duration was prevalent. There was greater requirement for maintenance and acute oral steroids, but no significant impact on healthcare utilisation/missed working days. Poorer asthma control was observed, along with structural disease and greater airflow obstruction.