Data Resource Profile: China Chronic Disease and Risk Factor Surveillance (CCDRFS)

Abstract

The China Chronic Disease and Risk Factor Surveillance (CCDRFS), conducted by the Chinese Centre for Disease Control and Prevention (China CDC), is a series of periodical cross-sectional nationally representative surveys covering 31 provinces in mainland China and conducted by China CDC that have collected data about Chinese adults regarding chronic and non-communicable diseases (NCDs) and related risk factors. It was first established in 2004, and there have been six field surveys in 2004, 2007, 2010, 2013, 2015 and 2018. Multistage stratified cluster sampling was used to select subjects. Of 776 571 adults invited, 746 020 finished the interview with a response rate of 96.1%. After data cleaning, 732 472 cases were included in the database, with 32 987 in 2004 (aged 18–69 years), 50 717 in 2007 (aged 15–69 years) and 98 120 in 2010, 176 534 in 2013, 189 605 in 2015 and 184 509 in 2018 (all aged ≥18 years). The data collected using household and individual questionnaires included: (i) demographic and socio-economic information, tobacco use, alcohol use, physical activity, diet, self-reported diagnosis and treatment of hypertension, diabetes, dyslipidaemia, myocardial infarction, stroke and other NCDs; (ii) height, weight, waist circumference and blood pressure; (iii) biochemical indicators, including glucose, lipids, glycated haemoglobin (HbA1c), uric acid, etc. CCDRFS data were managed by the National Centre for Chronic and Noncommunicable Disease Control and Prevention, China CDC. Using the newly established remote analysis platform, CCDRFS is expected to support more valuable research in China. Reliable and timely information on chronic and non-communicable diseases (NCDs) and their risk factors are fundamental for informing the development, implementation and evaluation of NCDs-related health policy. The China Chronic Disease and Risk Factor Surveillance (CCDRFS) is series of ongoing periodical nationally representative cross-sectional surveys among Chinese adults on their chronic health conditions (e.g. hypertension, diabetes, dyslipidaemia, stroke, myocardial infarction, cancer and chronic obstructive pulmonary disease) and related risk factors (e.g. smoking, harmful drinking, physical inactivity and unbalanced diet). The CCDRFS is established and organized by the National Centre for Chronic and Noncommunicable Disease Control and Prevention (NCNCD), the Chinese Centre for Disease Control and Prevention (China CDC), incorporated into the national Disease Surveillance Points (DSPs) system. A DSP area covers one rural county or one urban district. The details of the DSPs system have been reported elsewhere.1,2 Since its establishment in 2004, the CCDRFS was incorporated into the DSPs system, using its surveillance point as the primary sampling unit (PSU) in a multistage sampling framework. At the time of writing this paper, six field surveys had been carried out in 2004 (79 DSPs), 2007 (161 DSPs), 2010 (161 DSPs), 2013 (298 DSPs), 2015 (298 DSPs) and 2018 (298 DSPs). Figure 1 shows the locations of the CCDRFS surveillance points before and after expansion. Maps of surveillance points from the national Disease Surveillance Points system included in the China Chronic Disease and Risk Factor Surveillance surveys (A) Before the expansion of the Disease Surveillance Points system and (B) after the expansion. Within each PSU, subjects were selected using multistage stratified cluster sampling. Figure 2 shows the detailed sampling process. During the home visit to each selected household, basic demographic information (e.g. birth date and gender) were recorded for all household members. Subjects were selected from each household as follows. In CCDRFS 2004, among the subjects meeting the eligibility criteria, the person whose date of birth was closest to the 21st of the month was invited. In CCDRFS 2007, 2010 and 2013, the Kish method was used to select one eligible subject within every household.3 This method was released by Leslie Kish and was a rigorous, almost pure, probability method of sampling persons within households to be surveyed. Since 2015, all eligible subjects in the household have been invited to participate in the field survey. An average of 2.3 subjects per household were selected (range 1–10 subjects). The eligibility criteria included: (i) age ≥18 years (restricted to 18–69 years in 2004 and ranging from 15 to 69 years of age in 2007); (ii) having lived in the address for more than 6 months in the past 12 months; (iii) not pregnant; (iv) with no serious health condition or illness that would prevent the individual from participating, including intellectual disability or language disorder. Overall, among 776 571 adults invited, 746 020 completed the interview with an average response rate of 96.1%. After data cleaning, 732 472 cases were included in the database, with 32 987 in 2004 (18–69 years), 50 717 in 2007 (15–69 years) and 98 120 in 2010, 176 534 in 2013, 189 605 in 2015 and 184 509 in 2018 (all ≥18 years). Sampling frame of the China Chronic Disease and Risk Factor Surveillance. Each field survey started in August of the survey year, with most interviews and exams being completed in the same year. All remaining visits were completed by June of the next year. Trained interviewers from local centres for disease control and prevention (CDCs) carried out the face-to-face interviews, physical measurements, biochemical sample collection and sample pretreatment. For most subjects, interviews were conducted during home visits. Physical measurement and biochemical sample collections were conducted at a community health centre. During the home visit, an adult who knew the details of the household well, usually the householder, was first interviewed using a household questionnaire (including economic and environmental information). Subjects meeting the inclusion criteria were given an individual questionnaire on demographic information, lifestyle and history of chronic diseases. Smoking status was obtained using the Global Adult Tobacco Survey questionnaire.4 An alcohol frequency questionnaire was used to measure alcohol consumption. Physical activity has been obtained using the Global Physical Activity Questionnaire since 2010. Dietary behaviour and food consumption within the past 12 months were estimated using a food-frequency questionnaire.5 At the end of the home visit, the investigator gave the respondents an appointment letter, showing the time, place and any associated precautions of the physical measurements. All subjects were invited to a community health centre for physical measurements and to complete the questionnaire in the case of subjects who did not complete the individual questionnaire during the home visit. In 2004 and 2007, height was measured using wall-mounted stature meters; since 2010, height has been measured using mechanical anthropometry stadiometers. In 2004, weight was measured using metal body analogue weighing scales; since 2007, weight has been measured using the same model of electronic body scales, which were calibrated on a regular basis according to the standard protocol. Waist circumference was measured as the midpoint between the lower edge of the costal arch and the upper edge of the iliac crest while standing. In 2004, blood pressure was measured using a mercury sphygmomanometer. Since 2007, a digital device has been used. Biological sampling has been included in CCDRFS since 2010. Blood samples were obtained in the morning after an overnight fast for at ≥10 hours. In 2010, 2013 and 2018, subjects without a self-reported history of diabetes were given an oral glucose tolerance test by measuring plasma glucose before and 2 hours after drinking a solution containing 75 g anhydrous glucose. Also, in 2018, every subject was asked to take a urine sample at home on the morning of the physical examination and submit it on arrival at the health centre. Total cholesterol (TC), low-density-lipoprotein cholesterol (LDL-C), high-density-lipoprotein cholesterol (HDL-C), triglycerides (TG), uric acid and creatinine in serum, as well as creatinine and microalbumin in urine, were measured using an automatic biochemical analyser. Table 1 shows the data collected in each survey. Summary of information collected with the China Chronic Disease and Risk Factor Surveillance NA, not applicable; COPD, chronic obstructive pulmonary disease; NCDs, non-communicable diseases; OGTT, oral glucose tolerance test; HbA1c, glycated haemoglobin; TC, total cholesterol; LDL-C, low-density-lipoprotein cholesterol; HDL-C: high-density-lipoprotein cholesterol; TG, triglycerides. The ‘economy’ refers to the family's monthly or annual income. The ‘environment’ refers to the fuel used, including firewood, coal, natural gas or electricity, etc. Before 2015, all data were recorded using paper questionnaires, entered into bespoke data-entry software and delivered to the NCNCD via e-mail or an online data-transfer system. Since 2015, the NCNCD has deployed an integrated platform consisting of a tablet-assisted interview system and an online information-management system, which was adopted by all provincial and local CDCs. The data from the questionnaire, physical measurement, and blood and urine samples were collected electronically using the tablet-assisted system. The internet-based information-management system was used for sampling, on-site identity confirmation, quality control, lab-data submission, physical-examination reports and data download. All local labs passed the quality certification and underwent daily quality control during the testing process. The central labs were certified by the College of American Pathologists and performed all measurements using stringent quality-control procedures. The CCDRFS data have been used to assess the status and trend in major NCDs and related risk factors among Chinese adults. They informed the development of related national plans in China and were used to evaluate health promotion and NCD prevention programmes, such as the World Health Organization’s Noncommunicable Disease Monitoring Framework and its nine voluntary goals, the ‘Healthy China’ 2030 Planning Outline, the China Medium and Long-Term Plan for the Prevention and Control of Chronic Diseases (2017–2025) and the National Basic Public Health Service Projects. The CCDRFS also provided technical support for research in multiple fields, including global disease burden research6,7 and national surveys for specific NCDs (e.g. mental health,8 stroke,9 digestive system diseases and diabetes complications). More than 100 scientific papers and 5 reports have been published based on the CCDRFS data. These publications reported the national levels and trends in major NCDs and related risk factors. According to the CCDRFS data, the prevalence of diabetes among Chinese adults increased from 2.7% in 2002 (according to China National Nutrition and Health Survey data) to 9.7% in 2010 and 10.4% in 2013; 35.7% had prediabetes in 2013.10–12 The high prevalence of hypertension (27.8%) and low awareness, treatment and control rates (9.7%) were also observed among Chinese adults in 2013.13 Only 0.2% of adults had ideal cardiovascular health in 2010.14 Among adults with a high risk of developing atherosclerotic cardiovascular disease, 74.5% had uncontrolled LDL-C levels (≥2.6 mmol/L) and only 5.5% of them were treated with medication in 2013.15 Obesity and overweight varied significantly between 31 provinces in mainland China16 and the trends in urban and rural areas diverged since 2010, especially among women.17 Tobacco smoking remained highly prevalent among men (54.0% in 2010 and 51.8% in 2013) in China.18,19 E-cigarette use in China remained low but has increased substantially between 2015 (1.3%) and 2019 (1.6%).20 The major strength of the CCDRFS is its representativeness of both the national and the provincial populations of China. All surveys had large sample sizes and high response rates. It is also the only NCDs and risk factor surveillance system that is representative at the province level in China. The CCDRFS provides strong support for policy decisions for NCDs prevention and control of national and provincial governments. Furthermore, all DSPs in the CCDRFS also perform death registration and most also perform incidence registration for cardiovascular diseases and cancer. This provides a unique opportunity to monitor and study disease and death outcomes of the CCDRFS subjects. We are now exploring ways to link the CCDRFS data with other data sources, including the medical-record homepage system, turning the CCDRFS subjects into a dynamic cohort that will enable further research. Some limitations of the CCDRFS should be noted. First, the history of some NCDs (e.g. stroke, myocardial infarction and chronic obstructive pulmonary disease) was self-reported, which might underestimate the prevalence of these NCDs. However, many health surveys, such as the Behavioral Risk Factor Surveillance System in the USA, also collected self-reported disease history. Second, like most health surveys, only the non-institutionalized population was surveyed. People such as workers living in factory dormitories, soldiers living in barracks and university students were excluded, and this might decrease the proportion of younger adults among samples and introduce selection bias. Third, diet data on cooking-oil and salt consumption were also self-reported, which might underestimate the actual consumption. The nationwide status of tobacco use, alcohol use, physical inactivity, unhealthy diet, as well as the diagnosis, treatment and control of major NCDs (e.g. obesity, diabetes, hypertension and dyslipidaemia) can be found in the Report on Chronic Disease and Risk Factors among Chinese.21–24 The report of the CCDRFS 2018 is under preparation and is expected to be published in 2021. Visualizations of the published surveillance results will be available at www.ncddata.cn, which is under construction and will be deployed soon. Individual data from the CCDRFS are available to researchers by conducting a formal joint study with the NCNCD. Licensed researchers can analyse data and download the results of analyses via a remote system hosted at the NCNCD. Further inquiries on the application and use of the CCDRFS data can be obtained by contacting the data manager (at [email protected]). CCDRFS 2004–2013 and CCDRFS 2018 were approved by the ethical review committee of the NCNCD, China CDC. CCDRFS 2015 was approved by the ethical review committee of China CDC. Lim W., J.W., Lin W. and Ma Z. initiated the manuscript. Me Z. and Lim W. led the writing of the manuscript. All co-authors reviewed and contributed to the writing of the manuscript. Supplementary data are available at IJE online. In 2004 and 2007, the CCDRFS was funded by the NCNCD. Since 2010, the CCDRFS has been supported and funded by the Key Project of Public Health Program from the National Health Commission of the People's Republic of China. We would like to thank the participants, project staff, and diligent provincial and local staff of the CDCs for their participation and contributions. We also thank Dr Bin Zhou from the Imperial College London for his English-language polishing. None declared.

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