The CHNS is a follow-up survey regarding nutrition and food safety conducted by the Chinese Center for Disease Control and Prevention in collaboration with the Population Center of the University of North Carolina in the United States. The CHNS aimed to develop a longitudinal and multipurpose survey that could help the group measure health factors of interest, such as sociological, economic and demographic factors, for use by the CAPM (formerly the Chinese Academy of Preventive Medicine) and scholars . Since 1989, the CHNS has been conducted nine times (1989, 1991, 1993, 1997, 2000, 2004, 2006, 2009, and 2011) and has covered nine provinces (Liaoning, Heilongjiang, Jiangsu, Shandong, Henan, Hubei, Hunan, Guangxi and Guizhou), including urban and rural areas categorized by income (low, middle, and high). CHNS used a multistage stratified cluster random sampling method, and a weighted sampling scheme was used to randomly select four counties in each province . We used the 2011 health data of residents for this analysis. For the present analysis, the 2011 data were restricted to those of adult participants aged ≥ 18 years (n=13,052). Participants were excluded if the three blood pressure (SBP or DBP) measurements were not available in the survey (n=553), leaving 12,499 Chinese adults aged ≥ 18 years with complete blood pressure values for the present analysis.
In the CHNS, standard questionnaires were used to collect basic information and related biochemical indicators were measured in a national central lab in Beijing (medical laboratory accreditation certificate ISO 15189: 2007) with strict quality control . Blood pressure was measured by trained examiners using a mercury sphygmomanometer with a suitable cuff size according to a standard protocol . Three measurements were taken 10 minutes after rest, and the average of the three measurements was used for the analysis . In addition, the questionnaire asked whether the participant had a history of use of antihypertensive drugs.
Cardiovascular disease (CVD) history was defined by a self-reported previous diagnosis of myocardial infarction or stroke. The definitions of hypertension, recommended antihypertensive drug standards and recommended blood pressure targets for adults taking antihypertensive drugs referred to the 2017 ACC/AHA guideline and the 2010 Chinese guideline for the management of hypertension are presented in Table 1.
Continuous variables were presented as mean ± standard deviation (SD) or median [interquartile range, IQR], while categorical variables were expressed as counts and percentages (%). We calculated the distribution of the Chinese adults across five groups, including four groups that did not take antihypertensive medication (SBP / DBP <120 / <80, 120-129 / <80, 130-139 / 80-89, and ≥ 140 / 90 mmHg) and a group taking antihypertensive drugs. Patient groups were compared by x2 tests for categorical variables or one-way analysis of variance for continuous variables. We calculated the percentage and number (95% CI) of adults with hypertension in China and the percentage and number of people who were recommended to receive antihypertensive therapy based on the 2017 ACC/AHA guideline, the 2010 Chinese guideline, and the differences between the two guidelines (the 2017 ACC/AHA guideline but not the 2010 Chinese guideline). These calculations were performed in the general population and in different subgroups (such as groups with different ages and sexes). Moreover, the above method was used to calculate the Chinese demographic and clinical characteristics of blood pressure above the goal according to the 2017 ACC/AHA guideline and the 2010 Chinese guideline. Data from the sixth national census in 2010 were used to calculate the numbers of individuals with prevalent hypertension, who are recommended to take antihypertensive medications, and who have blood pressure above the goal. All analyses were performed with SPSS statistical software version 13.0 (SPSS Inc, Chicago, IL, USA) and SAS statistical software version 9.2 (SAS Institute Inc, Carey, NC, USA). A P value less than 0.05 was accepted as indicating statistical significance.