Are acute exacerbation blood eosinophil numbers associated with clinical pattern of preschool wheeze?

Abstract

Background: Wheezing in preschool children is common. Two clinical patterns are well described; episodic viral wheeze (EVW) and multiple trigger wheeze (MTW). MTW is associated with atopic disease, a higher risk of persistence of wheezing into school-age (Spycher et al 2008) and airway eosinophilia (Warke et al 2002). MTW is therefore often considered an early form of allergic asthma. Allergic asthma in older children and adults is strongly associated with increased absolute blood eosinophil counts but this has not been shown for preschool children with MTW. Aim: To investigate whether children with MTW have a higher absolute blood eosinophil count during an acute exacerbation than those with EVW. Methods: Children aged 6 months to 5 years old presenting to our hospital with acute wheeze were eligible to participate. Details of wheeze history were collected. Wheeze pattern was categorised as either EVW or MTW. A blood sample was obtained and a leucocyte differential cell count was performed. Differences in absolute blood eosinophil counts between the groups were determined by Mann-Whitney U test. Results: 60 children recruited (median age 33 months) were included in the analysis. For all children, median total eosinophil count was 0.125 x10 9 /L. There was no significant difference in median total eosinophil counts between those with EVW (0.145 x10 9 /L, n=38) and MTW (0.065 x10 9 /L, n=22), p=0.228. Conclusions: During acute exacerbation of preschool wheeze we found similar absolute blood eosinophil counts in children with MTW and EVW. The data suggests that during acute wheeze, blood eosinophil numbers are not raised in most preschool children and do not differ between EVW and MTW.