Abstract
A paper in the ERJ suggests that testing bronchodilator responsiveness is not helpful but the authors have not used the most appropriate method http://bit.ly/2MJR3KM
To the Editor:
The recent paper in the European Respiratory Journal by Janson et al. [1] on testing bronchodilator responsiveness suggests that it has no value in distinguishing asthma from COPD. The authors correctly state that “there are many different ways of defining bronchodilator reversibility.” However, they do not then mention any of them other than using the change in forced expiratory volume in 1 s (FEV1) standardised by the start value. This can lead to a sex and size bias in assessing bronchodilator response [2]. One method, that was recommended by the European Respiratory Society many years ago [3], standardises the change in FEV1 by the subject's predicted value and not their start value. Using this method it has been found that a change in FEV1 of 8% of predicted or more due to a bronchodilator was associated with a survival advantage [2]. This approach avoided all the pitfalls around the clinical diagnosis of COPD versus asthma. Previously it has been found that a change in FEV1 of 4% of predicted in COPD patients was associated with subjects being able to appreciate that their breathlessness was improved [4].
Before the respiratory community dismisses testing bronchodilator responsiveness based on the evidence of Janson et al. [1], it needs to look at expressing any change due to a bronchodilator as a percent of the subject's predicted value, as this has been shown to be free from potential sex and size bias and is better at distinguishing important clinical end-points.
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Footnotes
Conflict of interest: M.R. Miller has nothing to disclose.
- Received October 16, 2019.
- Accepted October 17, 2019.
- Copyright ©ERS 2019