Text and Data Mining valid from 2019-05-02
Received: 22 January 2018
Accepted: 22 April 2019
First Online: 2 May 2019
Ethics approval and consent to participate
: This study was approved by the ethics committee of Jikei University School of Medicine [No. 27–031(7938)]. Informed consent was waived by the ethics committee because we retrospectively collected data without using identifying information or applying any interventions.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.