Received: 28 January 2021
Accepted: 23 April 2021
First Online: 30 April 2021
: This study was approved by the Ethics Committee of The University of Tokyo (No. 2187) and conformed to the Declaration of Helsinki. Informed consent was obtained from all subjects included in this study. Informed consent was obtained from all subjects included in this study using the opt-out informed consent procedure. Namely, on admission, all of the inpatients were provided with a document explaining the policy of The University of Tokyo Hospital on protection of personal information and handling of samples of human origin. Any patients could request for suspension of use, elimination, provision of own personal information. In addition, a document that declares an opt-out policy by which any possible patient could refuse to be included in this study was uploaded on the web page of the The University of Tokyo Hospital.
: Not applicable.
: No author has any conflict of interest.