Chest
Volume 155, Issue 2, February 2019, Pages 331-341
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Original Research: Asthma
Change in FEV1 and Feno Measurements as Predictors of Future Asthma Outcomes in Children

https://doi.org/10.1016/j.chest.2018.10.009Get rights and content

Background

Repeated measurements of spirometry and fractional exhaled nitric oxide (Feno) are recommended as part of the management of childhood asthma, but the evidence base for such recommendations is small. We tested the hypothesis that reducing spirometric indices or increasing Feno will predict poor future asthma outcomes.

Methods

A one-stage individual patient data meta-analysis used data from seven randomized controlled trials in which Feno was used to guide asthma treatment; spirometric indices were also measured. Change in %FEV1 and % change in Feno between baseline and 3 months were related to having poor asthma control and to having an asthma exacerbation between 3 and 6 months after baseline.

Results

Data were available from 1,112 children (mean age, 12.6 years; mean %FEV1, 94%). A 10% reduction in %FEV1 between baseline and 3 months was associated with 28% increased odds for asthma exacerbation (95% CI, 3-58) and with 21% increased odds for having poor asthma control (95% CI, 0-45) 6 months after baseline. A 50% increase in Feno between baseline and 3 months was associated with 11% increase in odds for poor asthma control 6 months after baseline (95% CI, 0-16). Baseline Feno and %FEV1 were not related to asthma outcomes at 3 months.

Conclusions

Repeated measurements of %FEV1 that are typically within the “normal” range add to clinical risk assessment of future asthma outcomes in children. The role of repeated Feno measurements is less certain because large changes were associated with small changes in outcome risk.

Section snippets

Study Design

Authors of published RCTs in which measurements of Feno were used to guide asthma treatment in children18 were invited to provide anonymized data for IPD.19 The outcomes were asthma exacerbation (defined as a prescription of prednisolone during the follow-up period and derived using data provided by study authors) and poor asthma control (defined by per trial protocol by symptom score, and including FEV1 cutoff values in some trials11, 12, 16 but not including an asthma exacerbation).

Study Subjects

Data from seven pediatric RCTs were analyzed (Table 1)11, 12, 13, 14, 15, 16, 17; data from an eighth RCT could not be obtained.25 Details of population inclusion and exclusion criteria are presented in e-Appendix 1. The IPD included data on 1,112 participants. In two studies,14, 17 spirometry was measured at baseline and at 12 months only, and change in %FEV1 between baseline and 3 months could not be calculated. There was a predominance of male participants (58%) and mean (SD) age was 12.6

Discussion

This study sought to understand the relationship between changes in spirometric measurements and Feno and future asthma outcomes. The first finding was that, independent of all factors that might influence treatment decisions, falling %FEV1 (even within the range of 80% to 120% commonly considered as “normal”) was associated with increased odds for future asthma exacerbation and having uncontrolled asthma. A second finding was that an absolute change in Feno (Table 4) did not predict outcomes,

Acknowledgments

Author contributions: S. T. conceived the idea for the study, wrote the first draft of the manuscript, and is the guarantor of the study. S. T. and S. F. designed the study. All authors other than S. T. and S. F. contributed data for the analysis. S. F. undertook the analysis. All authors made contributions to the final manuscript.

Financial/nonfinancial disclosure: None declared.

Other contributions: The individual patient data analysis was carried out at the University of Aberdeen. Original

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    FUNDING/SUPPORT: The authors have reported to CHEST that no funding was received for this study.

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