Funding for this research was provided by:
Guangzhou Science and Technology Program key projects (2014Y2-00196, 201508020261)
Innovative Research Group Project of the National Natural Science Foundation of China (81870254)
Received: 16 February 2019
Accepted: 11 November 2019
First Online: 28 November 2019
Ethics approval and consent to participate
: This study was approved by the Guangzhou Medical Ethics Committee of the Chinese Medical Association (No. GDREC2015306H) and was conducted in accordance with the ethical standards of the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. All participants provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.