Funding for this research was provided by:
Japan Society for the Promotion of Science (15K19994)
Received: 26 July 2017
Accepted: 3 November 2017
First Online: 16 November 2017
Ethics approval and consent to participate
: This study was approved by the Research Ethics Committee of Osaka University Hospital (no. 15098–2). The requirement for written informed consent of participants and their parents was waived by the committee due to the retrospective nature of this study.
: Not applicable.
: All authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
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