Text and Data Mining valid from 2020-02-11
Received: 5 November 2019
Accepted: 28 January 2020
First Online: 11 February 2020
Ethics approval and consent to participate
: Written informed consents were obtained from patients and the parents of each patient, and this study was approved by the Research Ethics Board at the Asan Medical Center (approval number: S2019–1025-0001).
: Not applicable.
: The authors declare that they have no competing interests.