Funding for this research was provided by:
Received: 30 August 2019
Accepted: 20 February 2020
First Online: 4 March 2020
Ethics approval and consent to participate
: Written informed consent was obtained from the bereaved families of the patients at the time of autopsy. The study protocol was approved by the Ethics Committees of Tokyo Geriatric Hospital and Tokyo Medical and Dental University and authorized by TMDU Research Ethics Committee under the number 2016–011-02.
: Not applicable.
: The authors declare there are no competing interests.