Funding for this research was provided by:
Ministry of Education, Culture, Sports, Science and Technology (JP16K09931)
Japan Agency for Medical Research and Development (JP17fk0108307, JP18fk0108061, JP18fk0108052, JP18fk0108020)
Received: 17 April 2019
Accepted: 15 July 2019
First Online: 24 July 2019
Ethics approval and consent to participate
: Institutional review boards at NUH approved the study before its initiation (approval number 2017–0444 11811).
: Not applicable.
: The authors declare that they have no competing interests.