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Improved spirometric detection of small airway narrowing: concavity in the expiratory flow–volume curve in people aged over 40 years


Johns, DP and Das, A and Toelle, BG and Abramson, MJ and Marks, GB and Wood-Baker, R and Walters, EH, Improved spirometric detection of small airway narrowing: concavity in the expiratory flow-volume curve in people aged over 40 years, COPD: journal of chronic obstructive pulmonary disease, 12 pp. 3567-3577. ISSN 1541-2555 (2017) [Refereed Article]


Copyright Statement

Copyright 2017 Johns et al. Licensed under Creative Commons Attribution-NonCommercial 3.0 Unported (CC BY-NC 3.0)

DOI: doi:10.2147/COPD.S150280


Background and objective: We have explored whether assessing the degree of concavity in the descending limb of the maximum expiratory flow–volume curve enhanced spirometric detection of early small airway disease.

Methods: We used spirometry records from 890 individuals aged $40 years (mean 59 years), recruited for the Burden of Obstructive Lung Disease Australia study. Central and peripheral concavity indices were developed from forced expired flows at 50% and 75% of the forced vital capacity, respectively, using an ideal line joining peak flow to zero flow.

Results: From the 268 subjects classified as normal never smokers, mean values for postbronchodilator central concavity were 18.6% in males and 9.1% in females and those for peripheral concavity were 50.5% in males and 52.4% in females. There were moderately strong correlations between concavity and forced expired ratio (forced expiratory volume in 1 second/ forced vital capacity) and mid-flow rate (forced expiratory flow between 25% and 75% of the FVC [FEF25%–75%]; r=-0.70 to -0.79). The additional number of individuals detected as abnormal using the concavity indices was substantial, especially compared with FEF25%–75%M, where it was approximately doubled. Concavity was more specific for symptoms.

Conclusion: The inclusion of these concavity measures in the routine reports of spirometry would add information on small airway obstruction at no extra cost, time, or effort.

Item Details

Item Type:Refereed Article
Keywords:early airway disease, airflow obstruction, COPD
Research Division:Biomedical and Clinical Sciences
Research Group:Cardiovascular medicine and haematology
Research Field:Respiratory diseases
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:Johns, DP (Associate Professor David Johns)
UTAS Author:Das, A (Dr Aruneema Das)
UTAS Author:Wood-Baker, R (Professor Richard Wood-Baker)
UTAS Author:Walters, EH (Professor Haydn Walters)
ID Code:123128
Year Published:2017
Web of Science® Times Cited:6
Deposited By:Medicine
Deposited On:2017-12-17
Last Modified:2018-09-11
Downloads:83 View Download Statistics

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