Funding for this research was provided by:
Tianjin Municipal Health Bureau (15KG132)
Received: 1 November 2019
Accepted: 19 March 2020
First Online: 30 March 2020
Ethics approval and consent to participate
: This study was conducted in accordance with the Declaration of Helsinki. This study was approved by the Ethics Committee of Tianjin First Central Hospital. We explained to all participants the purpose of the study and how the data collected in this research study would be used. Written, informed consent was obtained from all participants before inclusion in the study.
: Not applicable.
: The authors declare that they have no competing interests.