the survey was supported by funds from chinese center for disease control and prevention (CDC), national center for non-communicable and chronic disease control and prevention,the technical development plan in shandong (implemented by shandong CDC,grant no. 2012GSF11828). We thank all investigators from the national ,provincial, and county-level CDC and all participants of the survey. We also acknowledeg ying cai and sonia Angell for their review of the study design and advice on implementation of the field intervention. The findings and conclusions in this reportol are those of the authors and do not necessarily represent the official position of the us centers for Disease control and prevention. There are no conflicts of interest relevant to this article