Received: 5 November 2019
Accepted: 13 April 2020
First Online: 19 April 2020
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of Kunming Medical University prior to the commencement of research. Written informed consent was obtained from all persons participating in the study, and the Ethics Committee of Kunming Medical University approved this consent procedure.
: Not applicable.
: The authors declare that there are no conflicts of interest.