Funding for this research was provided by:
Japan Ministry of Health, Labour and Welfare (H28-001, H30-004)
Received: 30 March 2019
Accepted: 28 May 2019
First Online: 7 June 2019
Ethics approval and consent to participate
: The ethical considerations of the current study, including the informed consent process and patient privacy measures, are based on the ethics guidelines for medical research in Japan [CitationRef removed]. The study protocol was approved by the Ethics Committee of the Graduate School of Medicine at Chiba University (no. 3154). If we amend our protocol, we will ask the Ethics Committee to revise it and will report this change in the paper.
: Not applicable.
: The authors declare that they have no competing interests.