Junshi Chen

Contrasting male and female trends in tobacco-attributed mortality in China: evidence from successive nationwide prospective cohort studies

Summary Background Chinese men now smoke more than a third of the worlds cigarettes, following a large increase in urban then rural usage. Conversely, Chinese women now smoke far less than in previous generations. We assess the oppositely changing effects of tobacco on male and female mortality. Methods Two nationwide prospective studies 15 years apart recruited 220 000 men in about 1991 at ages 40–79 years (first study) and 210 000 men and 300 000 women in about 2006 at ages 35–74 years (second study), with follow-up during 1991–99 (mid-year 1995) and 2006–14 (mid-year 2010), respectively. Cox regression yielded sex-specific adjusted mortality rate ratios (RRs) comparing smokers (including any who had stopped because of illness, but not the other ex-smokers, who are described as having stopped by choice) versus never-smokers. Findings Two-thirds of the men smoked; there was little dependence of male smoking prevalence on age, but many smokers had not smoked cigarettes throughout adult life. Comparing men born before and since 1950, in the older generation, the age at which smoking had started was later and, particularly in rural areas, lifelong exclusive cigarette use was less common than in the younger generation. Comparing male mortality RRs in the first study (mid-year 1995) versus those in the second study (mid-year 2010), the proportional excess risk among smokers (RR-1) approximately doubled over this 15-year period (urban: RR 1·32 [95% CI 1·24–1·41] vs 1·65 [1·53–1·79]; rural: RR 1·13 [1·09–1·17] vs 1·22 [1·16–1·29]), as did the smoking-attributed fraction of deaths at ages 40–79 years (urban: 17% vs 26%; rural: 9% vs 14%). In the second study, urban male smokers who had started before age 20 years (which is now typical among both urban and rural young men) had twice the never-smoker mortality rate (RR 1·98, 1·79–2·19, approaching Western RRs), with substantial excess mortality from chronic obstructive pulmonary disease (COPD RR 9·09, 5·11–16·15), lung cancer (RR 3·78, 2·78–5·14), and ischaemic stroke or ischaemic heart disease (combined RR 2·03, 1·66–2·47). Ex-smokers who had stopped by choice (only 3% of ever-smokers in 1991, but 9% in 2006) had little smoking-attributed risk more than 10 years after stopping. Among Chinese women, however, there has been a tenfold intergenerational reduction in smoking uptake rates. In the second study, among women born in the 1930s, 1940s, 1950s, and since 1960 the proportions who had smoked were, respectively, 10%, 5%, 2%, and 1% (3097/30 943, 3265/62 246, 2339/97 344, and 1068/111 933). The smoker versus non-smoker RR of 1·51 (1·40–1·63) for all female mortality at ages 40–79 years accounted for 5%, 3%, 1%, and <1%, respectively, of all the female deaths in these four successive birth cohorts. In 2010, smoking caused about 1 million (840 000 male, 130 000 female) deaths in China. Interpretation Smoking will cause about 20% of all adult male deaths in China during the 2010s. The tobacco-attributed proportion is increasing in men, but low, and decreasing, in women. Although overall adult mortality rates are falling, as the adult population of China grows and the proportion of male deaths due to smoking increases, the annual number of deaths in China that are caused by tobacco will rise from about 1 million in 2010 to 2 million in 2030 and 3 million in 2050, unless there is widespread cessation. Funding Wellcome Trust, MRC, BHF, CR-UK, Kadoorie Charitable Foundation, Chinese MoST and NSFC

Consumption of spicy foods and total and cause specific mortality: population based cohort study

Objective To examine the associations between the regular consumption of spicy foods and total and cause specific mortality. Design Population based prospective cohort study. Setting China Kadoorie Biobank in which participants from 10 geographically diverse areas across China were enrolled between 2004 and 2008. Participants 199 293 men and 288 082 women aged 30 to 79 years at baseline after excluding participants with cancer, heart disease, and stroke at baseline. Main exposure measures Consumption frequency of spicy foods, self reported once at baseline. Main outcome measures Total and cause specific mortality. Results During 3 500 004 person years of follow-up between 2004 and 2013 (median 7.2 years), a total of 11 820 men and 8404 women died. Absolute mortality rates according to spicy food consumption categories were 6.1, 4.4, 4.3, and 5.8 deaths per 1000 person years for participants who ate spicy foods less than once a week, 1 or 2, 3 to 5, and 6 or 7 days a week, respectively. Spicy food consumption showed highly consistent inverse associations with total mortality among both men and women after adjustment for other known or potential risk factors. In the whole cohort, compared with those who ate spicy foods less than once a week, the adjusted hazard ratios for death were 0.90 (95% confidence interval 0.84 to 0.96), 0.86 (0.80 to 0.92), and 0.86 (0.82 to 0.90) for those who ate spicy food 1 or 2, 3 to 5, and 6 or 7 days a week, respectively. Compared with those who ate spicy foods less than once a week, those who consumed spicy foods 6 or 7 days a week showed a 14% relative risk reduction in total mortality. The inverse association between spicy food consumption and total mortality was stronger in those who did not consume alcohol than those who did (P=0.033 for interaction). Inverse associations were also observed for deaths due to cancer, ischemic heart diseases, and respiratory diseases. Conclusion In this large prospective study, the habitual consumption of spicy foods was inversely associated with total and certain cause specific mortality, independent of other risk factors of death.

Association Between Diabetes and Cause-Specific Mortality in Rural and Urban Areas of China.

Importance In China, diabetes prevalence has increased substantially in recent decades, but there are no reliable estimates of the excess mortality currently associated with diabetes. Objectives To assess the proportional excess mortality associated with diabetes and estimate the diabetes-related absolute excess mortality in rural and urban areas of China. Design, Setting, and Participants A 7-year nationwide prospective study of 512 869 adults aged 30 to 79 years from 10 (5 rural and 5 urban) regions in China, who were recruited between June 2004 and July 2008 and were followed up until January 2014. Exposures Diabetes (previously diagnosed or detected by screening) recorded at baseline. Main Outcomes and Measures All-cause and cause-specific mortality, collected through established death registries. Cox regression was used to estimate adjusted mortality rate ratio (RR) comparing individuals with diabetes vs those without diabetes at baseline. Results Among the 512 869 participants, the mean (SD) age was 51.5 (10.7) years, 59% (n = 302 618) were women, and 5.9% (n = 30 280) had diabetes (4.1% in rural areas, 8.1% in urban areas, 5.8% of men, 6.1% of women, 3.1% had been previously diagnosed, and 2.8% were detected by screening). During 3.64 million person-years of follow-up, there were 24 909 deaths, including 3384 among individuals with diabetes. Compared with adults without diabetes, individuals with diabetes had a significantly increased risk of all-cause mortality (1373 vs 646 deaths per 100 000; adjusted RR, 2.00 [95% CI, 1.93-2.08]), which was higher in rural areas than in urban areas (rural RR, 2.17 [95% CI, 2.07-2.29]; urban RR, 1.83 [95% CI, 1.73-1.94]). Presence of diabetes was associated with increased mortality from ischemic heart disease (3287 deaths; RR, 2.40 [95% CI, 2.19-2.63]), stroke (4444 deaths; RR, 1.98 [95% CI, 1.81-2.17]), chronic liver disease (481 deaths; RR, 2.32 [95% CI, 1.76-3.06]), infections (425 deaths; RR, 2.29 [95% CI, 1.76-2.99]), and cancer of the liver (1325 deaths; RR, 1.54 [95% CI, 1.28-1.86]), pancreas (357 deaths; RR, 1.84 [95% CI, 1.35-2.51]), female breast (217 deaths; RR, 1.84 [95% CI, 1.24-2.74]), and female reproductive system (210 deaths; RR, 1.81 [95% CI, 1.20-2.74]). For chronic kidney disease (365 deaths), the RR was higher in rural areas (18.69 [95% CI, 14.22-24.57]) than in urban areas (6.83 [95% CI, 4.73-9.88]). Among those with diabetes, 10% of all deaths (16% rural; 4% urban) were due to definite or probable diabetic ketoacidosis or coma (408 deaths). Conclusions and Relevance Among adults in China, diabetes was associated with increased mortality from a range of cardiovascular and noncardiovascular diseases. Although diabetes was more common in urban areas, it was associated with greater excess mortality in rural areas.

Emerging tobacco-related cancer risks in China: A nationwide, prospective study of 0.5 million adults.

In China, cigarette consumption has increased substantially since the 1980s, almost exclusively in men. This study was aimed at assessing the emerging cancer risks.

Prevalence and correlates of airflow obstruction in ∼317 000 never-smokers in China

In China, the burden of chronic obstructive disease (COPD) is high in never-smokers but little is known about its causes in this group. We analysed data on 287 000 female and 30 000 male never-smokers aged 30–79 years from 10 regions in China, who participated in the China Kadoorie Biobank baseline survey (2004–2008). Prevalence of airflow obstruction (AFO) (pre-bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) <0.7 and below the lower limit of normal (LLN)) was estimated, by age and region. Cross-sectional associations of AFO (FEV1/FVC <0.7), adjusted for confounding, were examined. AFO prevalence defined as FEV1/FVC <0.7 was 4.0% in females and 5.1% in males (mean ages 51 and 54 years, respectively). AFO prevalence defined as FEV1/FVC <LLN was 5.9% and 5.2%, respectively. In females, odds ratios of AFO were positively associated with lower household income (1.63, 95% CI 1.55–1.72 for lowest versus highest income groups), prior tuberculosis (2.36, 95% CI 2.06–2.71), less education (1.17, 95% CI 1.12–1.23 for no schooling versus college education), rural region and lower body mass index. AFO was positively associated with cooking with coal but not with other sources of household air pollution. Associations were similar for males. AFO is prevalent in Chinese never-smokers, particularly among those with low socioeconomic status or prior tuberculosis, and in rural males. Airflow obstruction is prevalent in Chinese never-smokers and particularly associated with low socioeconomic status http://ow.ly/sG481

Associations of blood glucose and prevalent diabetes with risk of cardiovascular disease in 500 000 adult Chinese: the China Kadoorie Biobank

To examine the relationship of self‐reported diabetes, and of random blood glucose levels among individuals without known diabetes, with the prevalence of cardiovascular disease in Chinese adults.

Use of drug treatment for secondary prevention of cardiovascular disease in urban and rural communities of China: China Kadoorie Biobank Study of 0.5 million people

Aims Relatively little is known about the use of medication for the secondary prevention of cardiovascular disease (CVD) events in China, and the relevance to it of socioeconomic, lifestyle and health-related factors. Methods and results We analysed cross-sectional data from the China Kadoorie Biobank (CKB) of 512,891 adults aged 30–79 years recruited from 1737 rural and urban communities in China. Information about doctor-diagnosed ischaemic heart disease (IHD) and stroke, and the use of medication for the secondary prevention of CVD events, were recorded by interview. Multivariate logistic regression was used to estimate odds ratios (ORs) for use of secondary preventive treatment, adjusting simultaneously for age, sex, area and education. Overall, 23,129 (4.5%) participants reported a history of CVD (3.0% IHD, 1.7% stroke). Among them, 35% reported current use of any of 6 classes of drug (anti-platelet, statins, diuretics, ACE-I, β-blockers or calcium-channel blockers) for the prevention of CVD events, with the rate of usage greater in those with older age, higher levels of income, education, BMI or blood pressure. The use of these agents was associated positively with history of diagnosed hypertension (OR 7.5; 95% confidence intervals: 7.08–8.06) and diabetes (1.40; 1.28–1.52) and inversely with self-rated health status, but there was no association with years since diagnosis. Conclusions Despite recent improvements in hospital care in China, only one in three individuals with prior CVD was routinely treated with any proven secondary preventive drugs. The treatment rates were correlated with the existence of other risk factors, in particular evidence of hypertension.

Gallstone Disease and the Risk of Ischemic Heart Disease

Objective—Gallstone disease (GSD) is related to multiple cardiovascular risk factors; the present study was to prospectively examine the association between GSD and ischemic heart disease (IHD). Approach and Results—We examined the association of GSD with IHD among 199 292 men and 288 081 women aged 30−79 years in the China Kadoorie Biobank study. Participants with cancer, heart disease, and stroke at baseline were excluded. Cox proportional hazards regression model was used to estimate the association of GSD with IHD. The prevalence of self-reported GSD was 3.7% in men and 7.3% in women at baseline. During 3 431 124 person-years of follow-up between 2004 and 2013 (median, 7.2 years), we documented 10 245 incident IHD cases in men and 14 714 in women. As compared with men without GSD at baseline, the multivariate-adjusted hazard ratio for IHD was 1.11 (95% confidence interval, 1.02−1.22) for men with GSD; the respective hazard ratio was 1.27 (95% confidence interval, 1.20−1.34) in women and 1.23 (95% confidence interval, 1.17−1.28) in the whole cohort. The sex difference in IHD risk associated with GSD was statistically significant (P=0.009 for interaction with sex). In addition, we found that the association between GSD and IHD was stronger in nonhypertensive than in hypertensive women (P<0.001 for interaction). Conclusions—In this large prospective study, the presence of GSD was associated with an increased risk of incident IHD, independent of other risk factors of cardiovascular disease. Our findings suggest novel prevention strategy to mitigate heart disease through improvement of gastrointestinal health.

Major Dietary Patterns in Relation to General and Central Obesity among Chinese Adults.

Limited evidence exists for the association between diet pattern and obesity phenotypes among Chinese adults. In the present study, we analyzed the cross-sectional data from 474,192 adults aged 30–79 years from the China Kadoorie Biobank baseline survey. Food consumption was collected by an interviewer-administered questionnaire. Three dietary patterns were extracted by factor analysis combined with cluster analysis. After being adjusted for potential confounders, individuals following a traditional southern dietary pattern had the lowest body mass index (BMI) and waist circumference (WC); the Western/new affluence dietary pattern had the highest BMI; and the traditional northern dietary pattern had the highest WC. Compared to the traditional southern dietary pattern in multivariable adjusted logistic models, individuals following a Western/new affluence dietary pattern had a significantly increased risk of general obesity (prevalence ratio (PR): 1.06, 95% confidence interval (CI): 1.03–1.08) and central obesity (PR: 1.07, 95% CI: 1.06–1.08). The corresponding risks for the traditional northern dietary pattern were 1.05 (1.02–1.09) and 1.17 (1.25–1.18), respectively. In addition, the associations were modified by lifestyle behaviors, and the combined effects with alcohol drinking, tobacco smoking, and physical activity were analyzed. Further prospective studies are needed to elucidate the diet-obesity relationships.

Gender-specific association between tobacco smoking and central obesity among 0.5 million Chinese people: the China Kadoorie Biobank Study.

Objectives Lifestyle factors are well-known important modifiable risk factors for obesity; the association between tobacco smoking and central obesity, however, is largely unknown in the Chinese population. This study examined the relationship between smoking and central obesity in 0.5 million Chinese adults, a population with a low prevalence of general obesity, but a high prevalence of central obesity. Subjects A total of 487,527 adults (200,564 males and 286,963 females), aged 30-79 years, were enrolled in the baseline survey of the China Kadoorie Biobank (CKB) Study conducted during 2004-2008. Waist circumference (WC) and WC/height ratio (WHtR) were used as measures of central obesity. Results The prevalence of regular smokers was significantly higher among males (60.6%) than among females (2.2%). The prevalence of central obesity increased with age and BMI levels, with a significant gender difference (females>males). Of note, almost all obese adults (99.4%) were centrally obese regardless of gender. In multivariable regression analyses, adjusting for age, education, physical activity, alcohol use and survey site, regular smoking was inversely associated with BMI in males (standardized regression coefficients, β= -0.093, p<0.001) and females (β= -0.025, p<0.001). Of interest, in the BMI stratification analyses in 18 groups, all βs of regular smoking for WHtR were positive in both genders; the βs showed a significantly greater increasing trend with increasing BMI in males than in females. In the analyses with model adjustment for BMI, the positive associations between regular smoking and WHtR were stronger in males (β= 0.021, p<0.001) than in females (β= 0.008, p<0.001) (p<0.001 for gender difference). WC showed considerably consistent results. Conclusions The data indicate that tobacco smoking is an important risk factor for central obesity, but the association is gender-specific and depends on the adjustment for general obesity.