Received: 20 October 2020
Accepted: 18 May 2021
First Online: 29 May 2021
: Peking University Third Hospital Medical Science Research Ethics Committee (PUTH REC) is an independent organization composed of medical professionals, legal experts and nonmedical personnel. Its responsibility is to verify whether the clinical trial protocol and its attachments are ethical and to provide public guarantee to ensure that the safety, health and rights and interests of subjects are protected. Through strict examination, the consent has been waived for the following reasons: a. This study was designed as a population survey, and all the respondents were anonymous. The only record that subjects can be contacted in the study is the informed consent document. Signing informed consent may involve subject privacy or / or identity disclosure. b. The risk of this study is not greater than the minimum risk. c. Subjects were informed of the purpose and content of the study before accepting the survey. The subjects chose whether to fill in the questionnaire or not according to their own wishes. At any time during the questionnaire, subjects may discontinue their questionnaire if they feel offended or uncomfortable. And the questionnaire will not be collected for this study.
: This manuscript has not been published before and is not being considered for publication elsewhere.
: All authors declare that there are no competing interests.