Optimal spirometry thresholds for the prediction of chronic airflow obstruction: a multinational longitudinal study
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Author(s)
Type
Journal Article
Abstract
Introduction: Chronic airflow obstruction is key for COPD diagnosis but strategies for its early detection are limited. We aimed to define the optimal z-score thresholds for spirometry parameters to discriminate chronic airflow obstruction incidence.
Methods: The Burden of Obstructive Lung Disease study is a multinational cohort study. Information on respiratory symptoms was collected and pre- and post-bronchodilator spirometry was performed at baseline. Eighteen study sites were followed up with repeat measurements after a median of 8.4 years. We converted lung function measurements into z-scores using the Third National Health and Nutrition Survey reference equations. We used the Youden index to calculate the optimal z-score thresholds for discriminating chronic airflow obstruction incidence. We further examined differences by smoking status.
Results: We analysed data from 3057 adults (57% females, mean age: 51 years at baseline). Spirometry parameters were good at discriminating chronic airflow obstruction incidence (AUC 0.80-0.84), while respiratory symptoms performed poorly. The optimal z-score threshold was identified for pre-bronchodilator FEV1/FVC <-1.336, equivalent to the 9th percentile (sensitivity: 78%, specificity: 72%). All z-score thresholds associated with a lower post-bronchodilator FEV1/FVC and greater odds of chronic airflow obstruction at follow-up. The risk of chronic airflow obstruction was slightly greater for current smokers and, to some extent, never smokers with a pre-bronchodilator FEV1/FVC less than the 9th/10th percentiles at baseline, particularly among males.
Conclusions: Spirometry is better than respiratory symptoms at predicting chronic airflow obstruction incidence. A pre-bronchodilator FEV1/FVC <9th/10th percentiles, particularly among current smokers, could suggest early airflow obstruction or pre-COPD.
Methods: The Burden of Obstructive Lung Disease study is a multinational cohort study. Information on respiratory symptoms was collected and pre- and post-bronchodilator spirometry was performed at baseline. Eighteen study sites were followed up with repeat measurements after a median of 8.4 years. We converted lung function measurements into z-scores using the Third National Health and Nutrition Survey reference equations. We used the Youden index to calculate the optimal z-score thresholds for discriminating chronic airflow obstruction incidence. We further examined differences by smoking status.
Results: We analysed data from 3057 adults (57% females, mean age: 51 years at baseline). Spirometry parameters were good at discriminating chronic airflow obstruction incidence (AUC 0.80-0.84), while respiratory symptoms performed poorly. The optimal z-score threshold was identified for pre-bronchodilator FEV1/FVC <-1.336, equivalent to the 9th percentile (sensitivity: 78%, specificity: 72%). All z-score thresholds associated with a lower post-bronchodilator FEV1/FVC and greater odds of chronic airflow obstruction at follow-up. The risk of chronic airflow obstruction was slightly greater for current smokers and, to some extent, never smokers with a pre-bronchodilator FEV1/FVC less than the 9th/10th percentiles at baseline, particularly among males.
Conclusions: Spirometry is better than respiratory symptoms at predicting chronic airflow obstruction incidence. A pre-bronchodilator FEV1/FVC <9th/10th percentiles, particularly among current smokers, could suggest early airflow obstruction or pre-COPD.
Date Issued
2025-03-01
Date Acceptance
2024-08-30
Citation
ERJ Open Research, 2025, 11 (2)
ISSN
2312-0541
Publisher
European Respiratory Society
Journal / Book Title
ERJ Open Research
Volume
11
Issue
2
Copyright Statement
Copyright ©The authors 2024 This version is distributed under the terms of the Creative Commons Attribution Non-Commercial Licence 4.0. For commercial reproduction rights and permissions contact permissions@ersnet.org
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Identifier
https://publications.ersnet.org/content/erjor/early/2024/08/30/2312054100624-2024.abstract
Publication Status
Published
Article Number
00624
Date Publish Online
2024-09-27