Study Evaluates Lung Function Algorithm for Asthma Diagnosis in Children

Background on Asthma in Children

Asthma is recognized as one of the most prevalent chronic diseases affecting children, with approximately 1.1 million young patients receiving treatment in the United Kingdom. Traditionally, the diagnosis of asthma relies on recognizing a pattern of symptoms without any alternative explanations. However, prior research has highlighted issues of both misdiagnosis and overdiagnosis in asthma cases.

Introduction of a New Diagnostic Algorithm

In an effort to mitigate the problem of asthma overdiagnosis, the UK National Institute of Health and Care Excellence (NICE) has introduced a new diagnostic algorithm. This algorithm incorporates data from four sequential tests designed to assess lung function and inflammation, including:

1. Spirometry (measuring forced expiratory volume (FEV) and forced vital capacity (FVC))
2. Bronchodilator reversibility
3. Fractional exhaled nitric oxide (FeNO)
4. Peak expiratory flow variability

The algorithm sets specific cut-off values for these tests to aid in asthma diagnosis, which are as follows:

1. FEV: FVC ratio of less than 70%
2. Bronchodilator reversibility of at least 12%
3. FeNO of at least 35 parts per billion
4. Peak expiratory flow variability greater than 20%

Research Objectives and Methodology

A study conducted by Clare Murray and colleagues, published in The Lancet Child and Adolescent Health, aimed to assess the diagnostic effectiveness of three lung function tests individually as well as the overall utility of the proposed algorithm in children exhibiting asthma symptoms. The research utilized follow-up data from the Manchester Asthma and Allergy Study, a population-based birth cohort study.

Out of 1,184 children in the cohort, 722 participated in the follow-up at ages 13 to 16. Participants completed a questionnaire detailing any wheezing, coughing, or breathlessness experienced in the past year. Those reporting no such symptoms were categorized as non-asthmatic controls. Children previously diagnosed with asthma and who had experienced wheezing symptoms or received asthma treatment in the last year were classified as having “current asthma.”

Findings of the Study

The study revealed that an FEV: FVC ratio of less than 83.8%, a bronchodilator reversibility of at least 3.48%, and a FeNO level of at least 24 parts per billion provided more reliable indicators for diagnosing asthma. Statistical evaluations indicated that both FeNO (p < 0.0001) and FEV: FVC (p = 0.0075) were independently correlated with asthma, while bronchodilator reversibility did not show a significant association (p = 0.97).

Conclusion and Recommendations

Overall, the researchers identified a lack of agreement between the NICE algorithm and their epidemiological criteria for defining current asthma. The authors remarked, “Among symptomatic children who had completed three of the four tests, we were able to securely diagnose asthma in only two children using the algorithm, neither of whom met our epidemiological definition.” Consequently, the authors recommend that the NICE diagnostic guidelines for asthma should not be implemented for children.

Written by Cindi A. Hoover, Ph.D.
Reference: Murray C, Foden P, Lowe L, Durrington H, Custovic A, Simpson A. Diagnosis of asthma in symptomatic children based on measures of lung function: an analysis of data from a population-based birth cohort study. 2017. Lancet Child Adolesc Health. https://doi.org/10.1016/S2352-4642(17)30008-1