Funding for this research was provided by:
Korea Health Industry Development Institute (HI16C0526)
Received: 15 August 2017
Accepted: 10 April 2018
First Online: 20 April 2018
Ethics approval and consent to participate
: Not applicable. This survey did not need formal ethics approval as stated by national laws (Article 17 of the Statistics Act). We used only public data from the KHPS, which did not include any personal identification. The Korea Institute for Health and Social Affairs provided the data and permission to use and analyse it.
: The authors declare that they have no competing interests.
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