Article History
Received: 25 January 2018
Accepted: 2 March 2018
First Online: 14 March 2018
Compliance with ethical standards
:
: All authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national ethical guidelines for medical and health research involving human subjects and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was not obtained but the option of opting out was provided as approved by the ethics committee at Keio University School of Medicine.