Blood eosinophils in managing preschool wheeze: lessons learnt from a proof-of-concept trial

Background: Management of preschool wheeze is based predominantly on symptom pattern. Objective: To determine whether personalising therapy using blood eosinophils or airway bacterial infection results in fewer attacks compared to standard care. Methods: A proof-of-concept, randomised trial to investigate whether prescription of inhaled corticosteroids (ICS) guided by blood eosinophils, or targeted antibiotics for airway bacterial infection, results in fewer unscheduled healthcare visits (UHCV) compared to standard care. Children aged 1-5 years with >2 wheeze attacks in the previous year were categorised as episodic viral wheeze (EVW), or multiple trigger wheeze (MTW). The intervention group were prescribed ICS if blood eosinophils >3%, or targeted antibiotics if positive culture on induced sputum/cough swab. The control group received standard care. Primary outcome: UHCV at 4 months. Results: 60 children, median age 36.5 (range 14-61) months were randomised. Median blood eosinophils were 5.2 (range 0-21)%, 27/60 (45%) children were atopic and 8/60 (13%) had airway bacterial infection. There was no relationship between EVW, MTW and either blood eosinophils, atopic status, or infection. 67% in each group were prescribed ICS. 15/30 control subjects and 16/30 intervention group had UHCV over 4 months, p=0.8. Time to first UHCV was similar. 50% returned adherence monitors, in those, median ICS adherence was 67%. There were no differences in any parameter between those that did and did not have an UHCV. Conclusion: Clinical phenotype was unrelated to allergen sensitisation or blood eosinophils. ICS treatment determined by blood eosinophils did not impact UHCV, but ICS adherence was poor.