Article History
Received: 1 November 2017
Accepted: 19 June 2018
First Online: 29 June 2018
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: According to the Public Health Japanese Law, approval from an institutional review board is not required for human non-interventional studies. All procedures performed in studies involving human participants were in accordance with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual participants included in the study.