Text and Data Mining valid from 2020-04-29
Received: 6 February 2020
Accepted: 22 April 2020
First Online: 29 April 2020
Ethics approval and consent to participate
: Ethical approval was exempted by the medical ethics committee of Sichuan University Institutional Review Board (ExternalRef removed). Informed written consent to participate in the study has been obtained from participants.
: Not applicable.
: The authors declare that they have no competing interests.