Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2018 May 15;13:1583–1590. doi: 10.2147/COPD.S157165

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© 2018 Lee et al. This work is published and licensed by Dove Medical Press Limited

The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License (http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.

PMC Copyright notice

Flow diagram of the study participants.

Abbreviations: FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; KNHANES, Korean National Health and Nutritional Examination Survey; PHQ-9, Patient Health Questionnaire-9.