Published on in Vol 7, No 6 (2019): June
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/12245, first published
.
1 Guangdong Medical University, Dongguan, China
2 Baoan District Shajing Health Supervision Office, Shenzhen, China
3 Beijing Jiaotong University, Beijing, China
*these authors contributed equally