- Correspondence to Dr Maigeng Zhou, National Center for Chronic and Noncommunicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100050, China; and Dr Guoqing Hu, Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha 410078, China;
- Received December 19, 2017
- Revised March 28, 2018
- Accepted April 6, 2018
- First published April 24, 2018.
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