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International Journal of Chronic Obstructive Pulmonary Disease Volume 12, 2017 - Issue
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Original Research

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

David P Johns1 Faculty of Health, NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, TasmaniaCorrespondence[email protected]
,
Aruneema Das1 Faculty of Health, NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania
,
Brett G Toelle2 Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney;3 Sydney Local Health District, Sydney, New South Wales
,
Michael J Abramson4 Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria
,
Guy B Marks2 Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney;5 South Western Sydney Clinical School, University of New South Wales, Sydney, New South Wales
,
Richard Wood-Baker1 Faculty of Health, NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania
&
E Haydn Walters1 Faculty of Health, NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania;6 Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia
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Pages 3567-3577 | Published online: 13 Dec 2017

Figures & data

Figure 1 Variables used to quantify central and peripheral concavities (see text).

Notes: FEF50% and FEF75% are the measured values and Ref FEF50% and Ref FEF75% are the reference flows that would be obtained if the flow–volume curve had zero curvature, that is, a linear descending limb (dashed line).
Abbreviations: FEF25%–75%, forced expiratory flow between 25% and 75% of the FVC; FVC, forced vital capacity; PEF, peak expiratory flow; vPEF, volume expired to peak expiratory flow.
Figure 1 Variables used to quantify central and peripheral concavities (see text).

Table 1 Descriptive data for the sample

Figure 2 Relationship between lifetime tobacco consumption and post-BD spirometry and concavity, expressed as the difference relative to never smokers (nil pack-years).

Note: P-values refer to all points below the arrow.
Abbreviations: FEF25%–75%, forced expiratory flow between 25% and 75% of the FVC; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; post-BD, post-bronchodilator.
Figure 2 Relationship between lifetime tobacco consumption and post-BD spirometry and concavity, expressed as the difference relative to never smokers (nil pack-years).

Table 2 Spearman rank correlations for associations between post-BD concavity and spirometric variables

Table 3 Descriptive data for subjects classified as normalTable Footnotea

Table 4 Prevalence of abnormal post-BD concavities (central and peripheral) and abnormal spirometric variables

Figure 3 Post-BD relationships between central concavity and FEV1/FVC in males (n=424) and females (n=466).

Notes: The horizontal dotted line is the ULN for central concavity. The vertical dotted line in the two upper plots is the LLN for FEV1/FVC from Hankinson et alCitation34 and for the lower two plots, it is the fixed LLN of 70% from GOLD.Citation1 A negative value for FEV1/FVC indicates values below the LLN.

Abbreviations: FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, global initiative for chronic obstructive lung disease; LLN, lower limit of normal; Post-BD, post-bronchodilator; ULN, upper limit of normal.

Figure 3 Post-BD relationships between central concavity and FEV1/FVC in males (n=424) and females (n=466).Notes: The horizontal dotted line is the ULN for central concavity. The vertical dotted line in the two upper plots is the LLN for FEV1/FVC from Hankinson et alCitation34 and for the lower two plots, it is the fixed LLN of 70% from GOLD.Citation1 A negative value for FEV1/FVC indicates values below the LLN.Abbreviations: FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, global initiative for chronic obstructive lung disease; LLN, lower limit of normal; Post-BD, post-bronchodilator; ULN, upper limit of normal.

Figure 4 Post-BD relationships between peripheral concavity and FEV1/FVC in males (n=424) and females (n=466).

Notes: The horizontal dotted line is the ULN for peripheral concavity. The vertical dotted line in the two upper plots is the LLN for FEV1/FVC from Hankinson et alCitation34 and for the lower two plots, it is the fixed LLN of 70% from GOLD.Citation1 A negative value for FEV1/FVC indicates values below the LLN.

Abbreviations: FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, global initiative for chronic obstructive lung disease; LLN, lower limit of normal; Post-BD, post-bronchodilator; ULN, upper limit of normal.

Figure 4 Post-BD relationships between peripheral concavity and FEV1/FVC in males (n=424) and females (n=466).Notes: The horizontal dotted line is the ULN for peripheral concavity. The vertical dotted line in the two upper plots is the LLN for FEV1/FVC from Hankinson et alCitation34 and for the lower two plots, it is the fixed LLN of 70% from GOLD.Citation1 A negative value for FEV1/FVC indicates values below the LLN.Abbreviations: FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; GOLD, global initiative for chronic obstructive lung disease; LLN, lower limit of normal; Post-BD, post-bronchodilator; ULN, upper limit of normal.

Figure 5 Post-BD relationships between central and peripheral concavities and FEF25%–75% in males (n=424) and females (n=466).

Notes: The horizontal line is the ULN for central (upper plots) and peripheral (lower plots) concavities. The vertical dotted line is the LLN for FEF25%–75% from Hankinson et al.Citation34 A negative value for FEF25%–75% indicates values below the LLN.
Abbreviations: FEF25%–75%, forced expiratory flow between 25% and 75% of the FVC; LLN, lower limit of normal; Post-BD, post-bronchodilator; ULN, upper limit of normal.
Figure 5 Post-BD relationships between central and peripheral concavities and FEF25%–75% in males (n=424) and females (n=466).

Table 5 Sensitivity and specificity analyses of concavity for breathlessness on moderate activity (which occurred in 20% of the total population) in males and females whose FEV1/FVC or FEF25%–75% or FEV1/FVC ratio + FEF25%–75% were normal

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