Asthma and lower airway disease
Symptom-pattern phenotype and pulmonary function in preschool wheezers

https://doi.org/10.1016/j.jaci.2010.04.018Get rights and content

Background

Pulmonary function in preschool wheezing phenotypes based on wheeze onset and duration and atopic status has been extensively described but has not been studied in symptom-pattern phenotypes of episodic (viral) and multiple-trigger wheeze.

Objective

We investigated whether multiple-trigger wheezers were more likely to have abnormal pulmonary function and increased fraction of exhaled nitric oxide (FeNO) than episodic (viral) wheezers and whether multiple-breath wash-out was more sensitive at detecting abnormal pulmonary function than specific airways resistance (sRaw) in preschool wheezers.

Methods

FeNO, multiple-breath wash-out indices (lung clearance index [LCI] and conductive airways ventilation inhomogeneity [Scond]) and sRaw were measured in healthy children and those with recurrent wheeze aged 4 to 6 years. Subgroup analysis was performed according to current symptom-pattern (multiple-trigger vs episodic [viral]), atopic status (atopic vs nonatopic), and wheeze status (currently symptomatic vs asymptomatic).

Results

Seventy-two control subjects and 62 wheezers were tested. Multiple-trigger wheezers were associated with an average increase of 11% (95% CI, 7% to 18%; P < .001) in LCI, 211% (95% CI, 70% to 470%; P < .001) in Scond, and 15% (95% CI, 3% to 28%; P = .01) in sRaw compared with episodic (viral) wheezers. Pulmonary function in episodic (viral) wheezers did not differ significantly from control subjects. The presence of current atopy or wheeze was associated with higher FeNO (P = .05) but did not influence pulmonary function significantly. On average, LCI was abnormal in 39% (95% CI, 32% to 45%), Scond was abnormal in 68% (95% CI, 61% to 74%), and sRaw was abnormal in 26% (95% CI, 16% to 35%) of multiple-trigger wheezers.

Conclusions

Multiple-trigger wheeze is associated with pulmonary function abnormalities independent of atopic and current wheeze status. Scond is the most sensitive indicator of abnormal pulmonary function in preschool wheezers.

Section snippets

Methods

This prospective cross-sectional study was conducted at the UCL Institute of Child Health, London, United Kingdom. The Joint UCL/UCLH Ethics Committees and the local hospital ethics committees approved the study. Parents provided informed written consent for their children to participate.

Results

One hundred thirty-four children were recruited (see Table E1 in this article's Online Repository at www.jacionline.org). The distribution of sexes and ethnic groups was similar in the wheezers and healthy control subjects. A physician had previously assessed 58 of the 62 wheezers when acutely unwell and confirmed the presence of wheeze. Wheezers as a group were significantly younger and shorter, and more were atopic, with significantly higher FeNO, LCI, Scond, and sRaw values than healthy

Discussion

This study for the first time externally validates the hitherto strictly clinical concept of episodic (viral) and multiple-trigger wheeze. Multiple-trigger wheeze is associated with abnormal pulmonary function, whereas episodic (viral) wheeze is not. The symptom-pattern phenotype of preschool multiple-trigger wheeze is the patient characteristic most significantly associated with abnormal pulmonary function independent of atopic and current symptom status. In preschool wheezers, particularly

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    • Cited by (0)

    Supported by Asthma UK, the European Respiratory Society, and Smiths Medical.

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

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    Copyright © 2010 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.