• Quintero SantofimioValentinaVNational Heart and Lung Institute, Imperial College London, London, United Kingdom. Electronic address: vq20@imperial.ac.uk., Ben Knox-Brown, James Potts, Samuel Bartlett-Pestell, Johanna Feary, and AmaralAndre F SAFSNational Heart and Lung Institute, Imperial College London, London, United Kingdom; NIHR Imperial Biomedical Research Centre, London, United Kingdom..
• National Heart and Lung Institute, Imperial College London, London, United Kingdom. Electronic address: vq20@imperial.ac.uk.
• Chest. 2024 Oct 1; 166 (4): 712720712-720.

BackgroundSmall airways obstruction (SAO) is common in general populations. It has been associated with respiratory symptoms, cardiometabolic diseases, and progression to COPD over time. Whether SAO predicts mortality is largely unknown.Research QuestionIs spirometry-defined SAO associated with increased mortality?MethodsData were analyzed from 252,877 adult participants, aged 40 to 69 years at baseline, in the UK Biobank who had provided good-quality spirometry measurements. SAO was defined as the ratio of the forced expiratory volume in 3 s to the forced expiratory volume in 6 s less than the lower limit of normal. SAO was considered to be isolated if present when the FEV1/forced expiratory volume in 6 s ratio was normal (ie, greater than the lower limit of normal). A multivariable Cox regression model was used to assess the association of SAO, and isolated SAO, with all-cause and disease-specific mortality. Sex differences were investigated in these associations, and the primary analysis was repeated, excluding those who ever smoked. All models were adjusted for potential confounders such as sex, BMI, smoking status, smoking pack-years, assessment center, Townsend deprivation index, and ethnicity.ResultsA total of 59,744 participants with SAO were identified, of whom 24,004 had isolated SAO. A total of 5,009 deaths were reported over a median of 12.8 years of follow-up. Participants with SAO had increased all-cause (hazard ratio [HR], 1.31; 95% CI, 1.26-1.36), cardiovascular (HR, 1.39; 95% CI, 1.29-1.51), respiratory (HR, 2.20; 95% CI, 1.92-2.51), and neoplasm (HR, 1.23; 95% CI, 1.17-1.29) mortality risk. These associations were not modified by sex. However, in those who never smoked, only respiratory and cardiovascular mortality risk was associated with SAO. Isolated SAO was also associated with an increased mortality risk (HR, 1.14; 95% CI, 1.07-1.20).InterpretationIndividuals with SAO have an increased risk of all-cause and disease-specific mortality. Further studies are needed to determine whether SAO causes mortality or is a marker of underlying disease.Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.

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