Funding for this research was provided by:
the Japan Society for the Promotion of Science (JSPS KAKENHI Grant Number 17H01973)
Received: 20 April 2021
Accepted: 9 November 2021
First Online: 18 November 2021
: This study was conducted according to the guidelines laid down in the Declaration of Helsinki and all procedures involving study participants were approved by the Ethics Committee of the Faculty of Medicine, Toho University (approval of revised version: no. A19003_A17043 on Apr.17, 2019; first approval: no. A17043 on Sep 6, 2017). The study was registered as an intervention study in the UMIN Clinical Trials Registry (trial ID: UMIN000029252) on Sep 22, 2017 (ExternalRef removed). Written informed consent for the children was obtained from their guardians. Regarding the guardians themselves, completion and return of the questionnaires was not mandatory, and those who did so were deemed to have consented to participation after detailed explanation about the study.
: Not applicable.
: The authors declare that they have no competing interests.