Optimal spirometry thresholds for the prediction of chronic airflow obstruction: a multinational longitudinal study
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 st...
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| Main Authors: | , , , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
European Respiratory Society
2025-03-01
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| Series: | ERJ Open Research |
| Online Access: | http://openres.ersjournals.com/content/11/2/00624-2024.full |
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| Summary: | 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. 18 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% female, mean age: 51 years at baseline). Spirometry parameters were good at discriminating chronic airflow obstruction incidence (area under the curve 0.80–0.84), while respiratory symptoms performed poorly. The optimal z-score threshold was identified for pre-bronchodilator forced expiratory volume in 1 s to forced vital capacity ratio (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 <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. |
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| ISSN: | 2312-0541 |