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The China Health and Retirement Longitudinal Study (CHARLS) is a nationally representative longitudinal survey of persons in China 45 years of age or older and their spouses, including assessments of social, economic, and health circumstances of community-residents. CHARLS examines health and economic adjustments to rapid ageing of the population in China. The national baseline survey for the study was conducted between June 2011 and March 2012 and involved 17 708 respondents. CHARLS respondents are followed every 2 years, using a face-to-face computer-assisted personal interview (CAPI). Physical measurements are made at every 2-year follow-up, and blood sample collection is done once in every two follow-up periods. A pilot survey for CHARLS was conducted in two provinces of China in 2008, on 2685 individuals, who were resurveyed in 2012. To ensure the adoption of best practices and international comparability of results, CHARLS was harmonized with leading international research studies in the Health and Retirement Study (HRS) model. Requests for collaborations should be directed to Dr Yaohui Zhao (yhzhao@nsd.edu.cn). All data in CHARLS are maintained at the National School of Development of Peking University and will be accessible to researchers around the world at the study website. The 2008 pilot data for CHARLS are available at: http://charls.ccer.edu.cn/charls/. National baseline data for the study are expected to be released in January 2013.

BACKGROUND: In China, there have been few large prospective studies of the associations of body mass index (BMI) with overall and cause-specific mortality that have simultaneously controlled for biases that can be caused by pre-existing disease and smoking. METHODS: Prospective cohort study of 224 064 men, of whom 40 700 died during follow-up between 1990-91 and 2006. Analyses restricted to 142 214 men aged 40-79 years at baseline with no disease history and, to further reduce bias from pre-existing disease, at least 5 years of subsequent follow-up, leaving 17 800 deaths [including 4165 stroke, 1297 coronary heart disease (CHD), 3121 chronic obstructive pulmonary disease (COPD)]. Adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) per 5 kg/m(2) calculated within either a lower (15 to

Background: Vital registration of causes of death in China is incomplete with poor coverage of medical certification. Information on the leading causes of mortality will continue to rely on verbal autopsy (VA) methods. A new international VA form is being considered for data collection in China, but it first needs to be validated to determine its operating characteristics. Methods: Detailed medical records and clinical evidence for 3290 deaths (mostly adults) among residents of six cities representative of the urban Chinese population were reviewed by a panel of physicians and coded by experts to establish a reference underlying cause of death. Independently, families of the deceased were interviewed using a structured symptomatic questionnaire and a separate death certificate was prepared for each matching case (2102). Validity of the VA procedure was assessed using standard measurement criteria of sensitivity, specificity, and positive predictive value. Results: VA methods perform reasonably well in identifying deaths from several leading causes of adult deaths including stroke, several major cancer sites (lung, liver, stomach, oesophagus, and colorectal), and transport accidents. Sensitivity was less satisfactory in detecting deaths from several causes of major public health concern in China including ischaemic heart disease, chronic obstructive pulmonary disease, diabetes, and tuberculosis, and was particularly poor in diagnosing deaths from viral hepatitis, hypertension, and kidney diseases. Conclusions: VA is an imprecise tool for detecting leading causes of death among adults. However, much of the misclassification generally occurs within broad cause groups (e.g. CVD, respiratory diseases, and liver diseases). Moreover, compensating patterns of misclassification would appear to suggest that, in urban China at least, the method yields population-level cause-specific estimates that are reasonably reliable. These results suggest the possible utility of these methods in rural China, to back up the low coverage of medical certification of cause of death owing to poor access to health facilities there.

Background Forced expiratory volume in one second (FEV1) is inversely associated with mortality in Western populations, but few studies have assessed the associations of peak expiratory flow (PEF) with subsequent cause-specific mortality, or have used populations in developing countries, including China, for such assessments. Methods A prospective cohort study followed ∼170 000 Chinese men ranging in age from 40–69 years at baseline (1990–1991) for 15 years. In the study, height-adjusted PEF (h-PEF), which was uncorrelated with height, was calculated by dividing PEF by height. Hazard ratios (HR) for cause-specific mortality and h-PEF, adjusted for age, area of residence, smoking, and education, were calculated through Cox regression analyses. Results Of the original study population, 7068 men died from respiratory causes (non-neoplastic) and 22 490 died from other causes (including 1591 from lung cancer, 5469 from other cancers, and 10 460 from cardiovascular disease) before reaching the age of 85 years. Respiratory mortality was strongly and inversely associated with h-PEF. For h-PEF ≥ 250 L/min, the association was log-linear, with a hazard ratio (HR) of 1.29 (95% CI: 1.25–1.34) per 100 L/min reduction in h-PEF. The association was stronger but not log-linear for lower values of h-PEF. Mortality from combined other causes was also inversely associated with h-PEF, and the association was log-linear for all values of h-PEF, declining with follow-up, with HRs per 100 L/min reduction in h-PEF of 1.13 (1.10–1.15), 1.08 (1.06–1.11), and 1.06 (1.03–1.08) in three consecutive 5-year follow-up periods. Specifically, lower values of h-PEF were associated with higher mortality from cardiovascular disease and lung cancer, but not from other cancers. Conclusions A lower value of h-PEF was associated with increased mortality from respiratory and other causes, including lung cancer and cardiovascular disease, but its associations with the other causes of death declined across the follow-up period.

Background: National vital registration systems are the principal source of cause specific mortality statistics, and require periodic validation to guide use of their outputs for health policy and programme purposes, and epidemiological research. We report results from a validation of cause of death statistics from health facilities in urban China. Methods: 2917 deaths from health facilities located in six cities in China constituted the study sample. A reference diagnosis of the underlying cause was derived for each death, based on expert review of available medical records, and compared with that filed at registration. Sensitivity, specificity and positive predictive value were computed for specific causes/cause categories according to the International Classification of Diseases (ICD), including analyses based on quality of evidence scores for each cause. Patterns of misclassification by the registration system were studied for individual causes of death. Results: The registration system had good sensitivity in diagnosing cerebrovascular disease and several site specific cancers (lung, liver, stomach, colorectal, breast and pancreas). Sensitivity was average (50-75%) for some major causes of adult death in China, namely ischaemic heart disease (IHD), chronic obstructive lung disease (COPD), diabetes, and liver and kidney diseases, with compensatory misclassification patterns observed between several of them. Sensitivity was particularly low for hypertensive disease. Conclusions: Although diagnostic misclassification is not uncommon in urban death registration data, they appear to balance each other at the population level. Compensating misclassification errors suggest that caution is required when drawing conclusions about particular chronic causes of adult death in China. Investment is required to improve the quality of cause attribution for health facility deaths, and to assess the validity of cause attribution for home deaths. Periodic assessments of the quality of cause of death statistics will enhance their usability for health policy and epidemiological research. © Published by Oxford University Press on behalf of the International Epidemiology Association

BACKGROUND: Increased body mass index (BMI) is known to be related to ischaemic heart disease (IHD) in populations where many are overweight (BMI>or=25 kg/m2) or obese (BMI>or=30). Substantial uncertainty remains, however, about the relationship between BMI and IHD in populations with lower BMI levels. METHODS: We examined the data from a population-based, prospective cohort study of 222,000 Chinese men aged 40-79. Relative and absolute risks of death from IHD by baseline BMI were calculated, standardized for age, smoking, and other potential confounding factors. RESULTS: The mean baseline BMI was 21.7 kg/m2, and 1942 IHD deaths were recorded during 10 years of follow-up (6.5% of all such deaths). Among men without prior vascular diseases at baseline, there was a J-shaped association between BMI and IHD mortality. Above 20 kg/m2 there was a positive association of BMI with risk, with each 2 kg/m2 higher in usual BMI associated with 12% (95% CI 6-19%, 2P=0.0001) higher IHD mortality. Below this BMI range, however, the association appeared to be reversed, with risk ratios of 1.00, 1.09, and 1.15, respectively, for men with BMI 20-21.9, 18-19.9, and

BACKGROUND: In China, tobacco smoking accounts for approximately 800 000 deaths annually and evidence suggests that tobacco use is rising. To improve tobacco control initiatives directed at youth, we conducted a population-based survey of children ages 11-20 years, both in and out of school. While there have been previous school-based studies on smoking prevalence and smoking-related knowledge, attitudes, and behaviours among adolescents in China, including the Global Youth Tobacco Survey, this survey also describes smoking behaviour among non-student youth. This population is important as approximately 40% of Chinese youths aged 15-19 years have already discontinued their studies. METHODS: A survey of smoking behaviour and smoking-related knowledge and attitudes was administered to 24 000 youths (students and non-students of middle school age) in 24 disease surveillance points in China, selected to include equal numbers of urban and rural children. RESULTS: The prevalence rates of experimenting were 47.8% for boys and 12.8% for girls. The prevalence of regular smoking among non-students was higher (8.3%) compared with students (5.2%). The strongest predictor of regular smoking was peer influence with 44% reporting that they obtained their first cigarette from peers. The majority of youths were aware that smoking was a cause of several diseases and addictive; however, non-students were less aware than students. CONCLUSIONS: The evidence highlights the need for tobacco control interventions aimed at youths in China including non-student youths. For males, prevention programmes should extend into young adulthood.