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Int J Chron Obstruct Pulmon Dis. 2016 May 2;11:927-33. doi: 10.2147/COPD.S104644. eCollection 2016.

Vital capacity and COPD: the Swedish CArdioPulmonary bioImage Study (SCAPIS).

Author information

1
Section of Occupational and Environmental Medicine, Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
2
Department of Public Health and Clinical Medicine, Division of Medicine/Respiratory Medicine, Umeå University, Umeå, Sweden.
3
Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
4
Department of Clinical Science, Malmö, Lund University, Lund, Sweden.
5
Department of Respiratory Medicine and Department of Medicine and Health Sciences, Linköping University, Linköping, Sweden.
6
Respiratory Medicine Unit, Department of Medicine Solna, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.
7
Department of Internal Medicine/Lung Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
8
Department of Medical Sciences, Clinical Physiology and Respiratory, Allergy and Sleep Research, Uppsala University, Uppsala, Sweden.
9
Department of Translational Medicine, Lund University, Malmö, Sweden.
10
Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.

Abstract

BACKGROUND:

Spirometric diagnosis of chronic obstructive pulmonary disease (COPD) is based on the ratio of forced expiratory volume in 1 second (FEV1)/vital capacity (VC), either as a fixed value <0.7 or below the lower limit of normal (LLN). Forced vital capacity (FVC) is a proxy for VC. The first aim was to compare the use of FVC and VC, assessed as the highest value of FVC or slow vital capacity (SVC), when assessing the FEV1/VC ratio in a general population setting. The second aim was to evaluate the characteristics of subjects with COPD who obtained a higher SVC than FVC.

METHODS:

Subjects (n=1,050) aged 50-64 years were investigated with FEV1, FVC, and SVC after bronchodilation. Global Initiative for Chronic Obstructive Lung Disease (GOLD) COPDFVC was defined as FEV1/FVC <0.7, GOLDCOPDVC as FEV1/VC <0.7 using the maximum value of FVC or SVC, LLNCOPDFVC as FEV1/FVC below the LLN, and LLNCOPDVC as FEV1/VC below the LLN using the maximum value of FVC or SVC.

RESULTS:

Prevalence of GOLDCOPDFVC was 10.0% (95% confidence interval [CI] 8.2-12.0) and the prevalence of LLNCOPDFVC was 9.5% (95% CI 7.8-11.4). When estimates were based on VC, the prevalence became higher; 16.4% (95% CI 14.3-18.9) and 15.6% (95% CI 13.5-17.9) for GOLDCOPDVC and LLNCOPDVC, respectively. The group of additional subjects classified as having COPD based on VC, had lower FEV1, more wheeze and higher residual volume compared to subjects without any COPD.

CONCLUSION:

The prevalence of COPD was significantly higher when the ratio FEV1/VC was calculated using the highest value of SVC or FVC compared with using FVC only. Subjects classified as having COPD when using the VC concept were more obstructive and with indications of air trapping. Hence, the use of only FVC when assessing airflow limitation may result in a considerable under diagnosis of subjects with mild COPD.

KEYWORDS:

air trapping; asthma; epidemiology; general population; obstructive; slow vital capacity; spirometry

PMID:
27194908
PMCID:
PMC4859418
DOI:
10.2147/COPD.S104644
[Indexed for MEDLINE]
Free PMC Article

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