Received: 31 July 2019
Accepted: 12 November 2019
First Online: 28 November 2019
Compliance with ethical standards
: Each author certifies that he or she has no commercial associations that might pose a conflict of interest in connection with the submitted article.
: No funding for this study was required.
: This study was approved by the institutional review board of Asan Medical Center (AMC IRB No. 2018-1225).