Received: 15 March 2018
Accepted: 28 September 2018
First Online: 5 October 2018
Ethics approval and consent to participate
: This cross-sectional study protocol was approved by the Institution Ethics Committee of Toho University School of Medicine (Number: A16072_A17082). All participants provided written informed consent in accordance with the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.
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