Received: 29 October 2018
Accepted: 18 March 2019
First Online: 28 March 2019
Ethics approval and consent to participate
: This study analyzed existing data and therefore did not require approval from an ethics review board. This study used data from the Korea National Health and Nutrition Examination Survey (KNHANES), which has been subject to an annual review and approval by the KCDC Research Ethics Review Committee since 2007.
: Not applicable.
: The authors declare no conflicts of interest.
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