Interpretation for the group standards in data management for large population-based cohorts / 中华流行病学杂志

Precision medicine became the key strategy in development priority of science and technology in China. The large population-based cohorts become valuable resources in preventing and treating major diseases in the population, which can contribute scientific evidence for personalized treatment and precise prevention. The fundamental question of the achievements above, therefore, is how to construct a large population-based cohort in a standardized way. The Chinese Preventive Medicine Association co-ordinated experienced researchers from Peking University and other well-known institutes to write up two group standards Technical specification of data processing for large population-based cohort study (T/CPMA 001-2018) and Technical specification of data security for large population-based cohort study (T/CPMA 002-2018), on data management. The standards are drafted with principles of emphasizing their scientific, normative, feasible, and generalizable nature. In these two standards, the key principles are proposed, and technical specifications are recommended in data standardization, cleansing, quality control, data integration, data privacy protection, and database security and stability management in large cohort studies. The standards aim to guide the large population-based cohorts that have been or intended to be established in China, including national cohorts, regional population cohorts, and special population cohorts, hence, to improve domestic scientific research level and the international influence, and to support decision-making and practice of disease prevention and control.

Relationship between educational level and long-term changes of body weight and waist circumference in adults in China / 中华流行病学杂志

Objective: To evaluate the association of educational level with anthropometric measurements at different adult stages and their long-term changes in adults who participated in the second re-survey of China Kadoorie Biobank (CKB). Methods: The present study excluded participants who were aged >65 years, with incomplete or extreme measurement values, or with major chronic diseases at baseline survey or re-survey. The weight at age 25 years was self-reported. Body height, body weight and waist circumference at baseline survey (2004-2008) and re-survey (2013-2014) were analyzed. Results: The present study included 3 427 men and 6 320 women. Both body weight and waist circumference (WC) increased with age. From age 25 years to baseline survey (mean age 45.2±6.5), the mean weight change per 5-year was (1.70±2.63) kg for men and (1.27±2.10) kg for women. From baseline survey to re-survey (53.2±6.5), the mean changes per 5-year for body weight were (1.12±2.61) kg for men and (0.90±2.54) kg for women; and that for WC was (3.20±3.79) cm for men and (3.83±3.85) cm for women. Among women, low educational level was consistently associated with higher body mass index (BMI) and WC at age 25 years, baseline survey and re-survey. Among men, low educational level was associated with higher BMI at age 25 years. At baseline survey and re-survey, the educational level in men was not statistically associated with BMI; but men who completed junior or senior high school showed slight higher WC and increase of WC from baseline survey to re-survey than other male participants. Conclusions: Body weight and WC increased with age for both men and women. The associations of educational level with BMI and WC were different between men and women.

Prevalence of 'healthy lifestyle' in Chinese adults / 中华流行病学杂志

Objective: To examine the prevalence of 'healthy lifestyle' from data extracted from the China Kadoorie Biobank (CKB) of 0.5 million adults from ten areas across China. Methods: After excluding participants with self-reported histories of coronary heart disease, stroke or cancer, a total of 487 198 participants at baseline (2004-2008) and 22 604 participants at second survey (2013- 2014), were included for analysis. 'Healthy lifestyle' was defined as haing the following characteristics: a) never smoking or having stopped smoking for reasons other than illness; b) alcohol drinking <25 g/day (men)/<15 g/day (women); c) diet rich in vegetables, fruits, legumes and fish, but low in red meat; d) upper quarter of the physical activity level; e) body mass index of 18.5-23.9 kg/m(2) and waist circumstance <85 cm (men)/80 cm (women). We calculated the healthy lifestyle scores (HLS) by counting the number of all the healthy lifestyle factors, with a range from 0 to 6. Results: At baseline, prevalence rates of the above five healthy lifestyles (except physical activity) were 70.6%, 92.6%, 8.7%, 52.6% and 59.0%, respectively, with the mean HLS being 3.1±1.2. Most participants (81.4%) had2-4 healthy components, while only 0.7% (0.2% in men and 1.0% in women) of all the participants had all six healthy lifestyles. Participants who were women, at younger age, with more schooling and rural residents, were more likely to adhere to the healthy lifestyle. After ten years, the mean HLS showed a slight decrease. Conclusion: The prevalence of optimal lifestyles in Chinese adults appeared extremely low. Levels of 'healthy lifestyle' varied greatly among those populations with different socio-demographic characteristics across the ten areas in China.

Family history and risk of coronary heart disease / 中华流行病学杂志

Objective: To evaluate the association of family history with risk of major coronary events (MCE) and ischemic heart disease (IHD). Methods: After excluding participants with heart disease, stroke or cancer at baseline survey, a total of 485 784 participants from the China Kadoorie Biobank, who had no missing data on critical variables, were included in the analysis. Cox regression analysis was used to estimate the hazard ratios (HR) and 95% CI. Subgroup analyses were performed according to the baseline characteristics. Results: During a median of 7.2 years of follow-up, we documented 3 934 incident cases of MCE and 24 537 cases of IHD. In multivariable-adjusted models, family history was significantly associated with risk of MCE and IHD. The adjusted HRs (95%CI) were 1.41 (1.19-1.65) and 1.25 (1.18-1.33), respectively. History of disease among siblings was more strongly associated with early-onset MCE than parental history (HR=2.97, 95%CI: 1.80-4.88). Moreover, the association of family history with MCE and IHD was stronger in persons who were overweight or obesive, and the association between family history and MEC was stronger in smokers. Conclusion: This large-scale, prospective study indicated that family history was an independent risk factor for MCE and IHD in China. The intervention targeting major known lifestyle risk factors and the management of chronic diseases should be strengthened for Chinese population, especially for the individuals with family history were at high risk.

Levels of calcaneus bone mineral density in adults from 10 regions of China / 中华流行病学杂志

Objective: To describe the regional and population-related differences in calcaneus bone mineral density (BMD) across ten regions of China. Methods: Based on the results: from the second Re-survey of China Kadoorie Biobank project, in which 5% of the surviving participants were interviewed during 2013-2014 and 24 677 participants aged 38-87 years were included in the study. We excluded those people with missing data for BMD and important variables. Calcaneus BMD was measured using the quantitative ultrasound bone densitometer. We analyzed four indexes, including broadband ultrasound attenuation (BUA), speed of sound (SOS), stiffness index (SI), and T score. Results The average calcaneus BMDs of the present population were: BUA (109.7±12.6) dB/MHz, SOS (1 554.7±45.6) m/s, SI (88.3±18.8), T score (-0.74±1.28). Urban residents showed higher calcaneus BMD, so as in men. The calcaneus BMD decreased by age, with a larger decline seen in women. Current smokers and postmenopausal women presented lower calcaneus BMD, while in those who frequently drank milk or yogurt or being physically more active, had higher calcaneus BMD. Conclusion: Calcaneus BMD varied greatly among people from the ten regions of CKB study and among participants having different demographic characteristics, lifestyle behaviors or health conditions.

Association between central obesity and risk for heart disease in adults in China: a prospective study / 中华流行病学杂志

Objective: To understand the association between central obesity, assessed by waist circumference, and the risks for ischemic heart disease (IHD), major coronary event (MCE), and IHD death. Methods: After excluding participants with heart disease, stroke, cancer, COPD, and diabetes at baseline survey, we included a total of 428 595 participants from the China Kadoorie Biobank for the analysis. The baseline survey was conducted from June 2004 to July 2008. We used Cox proportional hazards model to estimate the hazard ratio (HR) and 95%CI. Results: During an average 9.1 years of follow-up (3 803 637 person-years), we documented 26 900 incident cases of IHD, 4 320 cases of MCE, and 2 787 of deaths from IHD. After adjustment for possible confounders and BMI, central obesity was found to be associated with increased risks for IHD, MCE, and IHD death. The adjusted HRs (for the participants who had waist circumference of 85.0-89.9 cm in men and 80.0-84.9 cm in women were 1.13 (95%CI: 1.09-1.17) for IHD, 1.15 (95%CI: 1.05-1.26) for MCE and 1.11 (95%CI: 0.98-1.24) for IHD death. The respective HRs for those central obese participants (men ≥90.0 cm, women ≥85.0 cm) were 1.29 (95%CI: 1.24-1.34), 1.30 (95%CI: 1.17-1.44) and 1.32 (95%CI: 1.16-1.51). Further stratification analysis according to BMI showed that the risks for incident IHD, MCE, and IHD death increased along with the increase of waist circumference even in the participants with normal weight. Conclusion: This large-scale prospective study revealed that central obesity was an independent risk factor for IHD in adults in China, and the risk of IHD would increase with the increase of waist circumference.

Epidemiological characteristics of household fuel use in 10 areas of China / 中华流行病学杂志

Objective: To describe the characteristics of cooking and heating fuel use in participants from the China Kadoorie Biobank (CKB) study. Methods: The CKB study recruited 512 891 adults from 10 areas in China during 2004-2008. Information on cooking fuel and heating fuel was collected using a questionnaire in baseline survey. The proportions of various fuels used in different areas, in different populations, and at different time points were calculated and compared. Results: Overall, 52.1% participants used solid fuel for cooking or heating. Rural areas had higher prevalence of solid fuel use than urban areas. The percentage of participants using solid fuel for cooking was 36.1% (coal 20.1%, wood/charcoal 16.0%); The percentage of participants using solid fuel for heating was 36.7% (coal 22.7%, wood/charcoal 14.0%). The prevalence of solid fuel use and the fuel type mainly used varied widely across 10 areas. The proportion of clean fuel use was lower in less-educated and lower-income people. Household coal and wood/charcoal use showed a declining trend, which was more remarkable in urban areas. Conclusion: There are still a large number of rural residents and people with low income relying on solid fuel in China, which is a serious public health concern.

Associations between family history of major chronic diseases and healthy lifestyles in Chinese adults / 中华流行病学杂志

Objective: To examine the associations between family history of major chronic diseases and healthy lifestyle in adults in China. Methods: Data were from the baseline and second survey of China Kadoorie Biobank study, which were conducted during 2004-2008 and 2013-2014, respectively. After excluding participants with self-reported histories of coronary heart disease, stroke, cancer or diabetes, a total of 461 213 adults from baseline survey and 20 583 adults from second survey were included in the current study. Participants who reported a family history of acute myocardial infarction, stroke, cancer, or diabetes of any first-degree relative (i.e., biological father, mother, or siblings) were defined as having a family history of major chronic diseases. Healthy lifestyles were defined as current nonsmoking, non-excessive alcohol drinking, eating vegetables and fruits daily, upper quarter of physical activity level, body mass index (BMI) of (18.5-23.9) kg/m(2), and waist- to-hip ratio (WHR) <0.90 (man)/<0.85 (women). Results: At baseline survey, 36.5% of the participants had family history of major chronic diseases. Proportions of the above six healthy lifestyles were 70.5%, 93.0%, 18.0%, 25.0%, 53.4%, and 43.5%, respectively. Compared with participants without family history, the proportions of current nonsmoking, non-excessive drinking, normal BMI, and normal WHR were lower in participants with family history of major chronic diseases, while the proportions of eating vegetables and fruits daily, and being physically active, were higher. In general, the absolute differences in these proportions between participants with and without a family history were only slight. Similar results were observed when other family history status (the type or number of disease, the category or number of affected family members) were analysed. The association between family history of major chronic diseases and healthy lifestyles was consistently observed in the second survey 10 years later. Conclusion: In Chinese population, adults with family history of major chronic diseases did not adopt healthier lifestyles.