Funding for this research was provided by:
Natural Science Foundation of Guangxi Province (2013GXNSFBA019131, 2015GXNSFAA139171)
Education Department of Guangxi Zhuang Autonomous Region (Guangxi Scholarship Fund)
Received: 20 October 2019
Accepted: 23 December 2019
First Online: 28 December 2019
Ethics approval and consent to participate
: The study was approved by the ethics committee of the First Affiliated Hospital of Guangxi Medical University and was carried out in accordance with the Declaration of Helsinki. All participants provided informed consent.
: Not applicable.
: The authors declare that they have no competing interests.