Asthma and lower airway disease
Exhaled nitric oxide distinguishes between subgroups of preschool children with respiratory symptoms

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Background

Respiratory symptoms are common in early childhood. The clinical characterization of disease presentation and hence its likely disease progression has so far been proven difficult.

Objective

To investigate whether exhaled nitric oxide (NO) could be helpful to distinguish between subgroups of nonwheezy and wheezy young children less than 4 years of age.

Methods

Exhaled NO was measured in 391 children (age 3-47 months) with nonwheezy and wheezy respiratory symptoms. Children were divided into 3 groups: children with recurrent cough but no history of wheeze (group 1), with early recurrent wheeze and a loose index for the prediction of asthma at school age (group 2), and with frequent recurrent wheeze and a stringent index for the prediction of asthma at school age (group 3).

Results

Children from group 3 showed significantly higher median (interquartile range) fractional exhaled NO (FeNO) levels (11.7 [11.85]) than children from groups 1 (6.5 [5.5]; P < .001) and 2 (6.4 [6.5]; P < .001). No difference in FeNO levels was found between children from groups 1 and 2 (P = .91).

Conclusion

Wheezy young children less than 4 years of age with a stringent index for the prediction of asthma at school age have elevated levels of FeNO compared with children with recurrent wheeze and a loose index for the prediction of asthma at school age or children with recurrent cough.

Section snippets

Study population

This is a prospective cohort study with 391 young children less than 4 years of age consecutively undergoing assessment for respiratory symptoms at the University Children's Hospital Zürich, Switzerland, between 2000 and 2004. Exclusion criteria were a diagnosis of a specific respiratory disease such as cystic fibrosis, primary ciliary dyskinesia, interstitial lung disease, pneumonia, or tuberculosis and/or current upper airway infection or inability to obtain an appropriate FeNO measurement.

Results

Group 1 (children with cough) consisted of more girls (P = .023) and older children (P < .026) compared with groups 2 and 3. Allergic sensitization as assessed by RAST was more frequent in group 3 compared with groups 1 and 2. No differences between groups were noted for percentage of blood eosinophils or prenatal or postnatal passive smoke exposure. Less than 1/3 of the children were on current inhaled corticosteroid (ICS) treatment at the time of FeNO measurement, significantly more in groups

Discussion

We have shown that the measurement of exhaled NO differentiates between subgroups of young children less than 4 years of age with wheezy and nonwheezy respiratory symptoms. Children with frequent recurrent wheeze and a stringent asthma predictive index10 (group 3) showed significantly higher FeNO values than children with nonfrequent recurrent wheeze and a loose asthma predictive index (group 2) or nonwheezy children with chronic or recurrent cough (group 1). Although there was an overlap in

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    Supported by an unrestricted grant by GlaxoSmithKline Switzerland.

    Disclosure of potential conflict of interest: The authors have declared that they have no conflict of interest.

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