Funding for this research was provided by:
Ministry of Science and ICT (2017-0-00588)
Received: 30 October 2018
Accepted: 1 May 2019
First Online: 13 June 2019
Ethics approval and consent to participate
: The KNHANES was approved by the Institutional Review Board of the Korea Centers for Disease Control (IRB No. 1401–047-547), and all participants signed an informed consent form. This study meets the Helsinki Declaration-based ethical principles for medical research involving human subjects.
: Not applicable.
: The authors declare that they have no competing interests.
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