Received: 2 August 2020
Accepted: 23 November 2020
First Online: 3 December 2020
Ethics approval and consent to participate
: The study protocol complied with the Helsinki Declaration standards and was approved by the institutional review board of Shimane University Hospital. Written informed consent was substituted by an opt-out fashion according to the recommendation of the ethical committee because this study employed an observational design, which provided patients with no interventions, and patients with delirium could not voluntarily consent by themselves. This study was registered with the University Hospital Medical Information Network Clinical Trials Registry, as accepted by the International Committee of Medical Journal Editors (UMIN000032646).
: Not applicable.
: The authors declare that they have no competing interests.