Background
Management of preschool wheeze is based predominantly on symptom patterns.

Objective
To determine whether personalizing therapy using blood eosinophils or airway bacterial infection results in fewer attacks compared with standard care.

Methods
A proof-of-concept, randomized trial to investigate whether the prescription of inhaled corticosteroids (ICS) guided by blood eosinophils, or targeted antibiotics for airway bacterial infection, results in fewer unscheduled healthcare visits (UHCVs) compared with standard care. Children aged 1–5 years with ≥2 wheeze attacks in the previous year were categorized as episodic viral wheeze (EVW) or multiple trigger wheeze (MTW). The intervention group was prescribed ICS if blood eosinophils ≥3%, or targeted antibiotics if there is positive culture on induced sputum/cough swab. The control group received standard care. The primary outcome was UHCV at 4 months.

Results
60 children, with a median age of 36.5 (range 14–61) months, were randomized. Median blood eosinophils were 5.2 (range 0–21)%, 27 of 60 (45%) children were atopic, and 8 of 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 of 30 control subjects and 16 of 30 patients in the intervention group had UHCV over 4 months (p = .8). The 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 who did and did not have an UHCV.

Conclusion
Clinical phenotype was unrelated to allergen sensitization or blood eosinophils. ICS treatment determined by blood eosinophils did not impact UHCV, but ICS adherence was poor.