[Incidence of chronic obstructive pulmonary disease and risk factors in the Suzhou cohort]

Objective: To understand the incidence of chronic obstructive pulmonary disease (COPD) in the Suzhou cohort, and explore the risk factors for the development of COPD in Suzhou, and provide a scientific basis for COPD prevention. Methods: This study was based on the China Kadoorie Biobank project in Wuzhong District, Suzhou. After excluding individuals with airflow obstruction and self-reported chronic bronchitis, emphysema, or pulmonary heart disease at baseline, 45 484 individuals were finally included in the analysis. Cox proportional risk models were used to analyze risk factors of COPD and calculate hazard ratios and 95% confidence interval (CI) in the Suzhou cohort. The effect modifications of smoking on the association between other risk factors and COPD were evaluated. Results: Complete follow-up was available through December 31, 2017. Participants were followed up for a median of 11.12 years, and 524 individuals were diagnosed with COPD during the follow-up period; the incidence was 105.54 per 100 000 person-years. Multivariate Cox proportional risk regression models showed that age (HR=3.78, 95%CI:3.32-4.30), former smoking (HR=2.00, 95%CI:1.24-3.22), current smoking (<10 cigarettes/day, HR=2.14, 95%CI:1.36-3.35;≥10 cigarettes/day, HR=2.69, 95%CI:1.60-4.54), history of respiratory disease (HR=2.08, 95%CI:1.33-3.26), daily sleep duration ≥10 hours (HR=1.41, 95%CI:1.02-1.95) were associated with increased risk of COPD. However, education level of primary school and above (primary or junior high school, HR=0.65, 95%CI:0.52-0.81; high school and above, HR=0.54, 95%CI:0.33-0.87), consuming fresh fruit daily (HR=0.59, 95%CI:0.42-0.83) and consuming spicy food weekly (HR=0.71, 95%CI:0.53-0.94) were associated with reduced risk of COPD. Conclusions: The incidence of COPD is low in Suzhou. Older age, smoking, history of respiratory disease, and long sleep duration were risk factors for the development of COPD in the Suzhou cohort.

Household air pollution from solid fuel use and depression among adults in rural China: evidence from the China Kadoorie Biobank data

BACKGROUND

Solid fuels are still widely used for cooking in rural China, leading to various health implications. Yet, studies on household air pollution and its impact on depression remain scarce. Using baseline data from the China Kadoorie Biobank (CKB) study, we aimed to investigate the relationship between solid fuel use for cooking and depression among adults in rural China.

METHODS

Data on exposure to household air pollution from cooking with solid fuels were collected and the Chinese version of the World Health Organization Composite International Diagnostic Interview short-form (CIDI-SF) was used to evaluate the status of major depressive episode. Logistic regression analysis was performed to investigate the association between solid fuel use for cooking and depression.

RESULTS

Amongst 283,170 participants, 68% of them used solid fuels for cooking. A total of 2,171 (0.8%) participants reported of having a major depressive episode in the past 12 months. Adjusted analysis showed that participants who had exposure to solid fuels used for cooking for up to 20 years, more than 20 to 35 years, and more than 35 years were 1.09 (95% CI: 0.94-1.27), 1.18 (95% CI: 1.01-1.38), and 1.19 (95% CI: 1.01-1.40) times greater odds of having a major depressive episode, respectively, compared with those who had no previous exposure to solid fuels used for cooking.

CONCLUSION

The findings highlight that longer exposure to solid fuels used for cooking would be associated with increased odds of major depressive episode. In spite of the uncertainty of causal relationship between them, using solid fuels for cooking can lead to undesirable household air pollution. Reducing the use of solid fuels for cooking by promoting the use of clean energy should be encouraged.

[Relationship between smoking and the risk of morbidity of chronic obstructive pulmonary diseases among residents aged 30 years and above in Sichuan Province: a prospective study]

Objective: To investigate the morbidity of chronic obstructive pulmonary diseases (COPD) in residents aged 30 years and above in Sichuan Province, and analyze the effect of smoking on the risk of morbidity on COPD. Methods: From 2004 to 2008, people were randomly selected from Pengzhou, Sichuan Province. All the local people aged 30-79 years were asked to receive questionnaire survey, physical examination and pulmonary function testing, and long-term follow-up to determine the morbidity of COPD. Cox proportional hazard regression model was used to analyze the relationship between smoking and COPD. Results: In 46 540 participants, the current smoking rates were 67.31% in males and 8.67% in females, there were 3 101 new cases of COPD, with a cumulative incidence of 6.66%. Adjusted for age, gender, occupation, marriage, income level, educational level, BMI, daily total physical activity, current cooking frequency, whether there was smoke exhaust device at present and frequency of passive smoking exposure, multivariate Cox proportional hazard regression analysis showed that compared with the non-smoking population, current smoking and quitting smoking increased the risk of COPD, with HR of 1.42 (95%CI:1.29-1.57) and 1.34 (95%CI:1.16-1.53). Compared with people who never or occasionally smoke, the risk of morbidity on COPD increased with the increase of average daily smoking volume, mixed smoking at present, mixed smoking at the beginning increased the risk of COPD, with HR of 1.79 (95%CI: 1.42-2.25) and 2.12 (95%CI: 1.53-2.92), started smoking at the age of <18 years old and ≥18 years old increased the risk of COPD, with HR of 1.61 (95%CI:1.43-1.82) and 1.34 (95%CI: 1.22-1.48), inhaling into the mouth, throat and lung during smoking increased the risk of COPD, with HR of 1.30 (95%CI: 1.16-1.45), 1.63 (95%CI: 1.45-1.83) and 1.37 (95%CI: 1.21-1.55). Adjusted for multiple confounding factors and adjusted for regression dilution bias, the average daily smoking volume, the age of starting smoking and the depth of smoking inhalation had an impact on the incidence of COPD, and the gender difference was particularly prominent. Conclusions: Smoking increased the risk of morbidity on COPD, which was related to the average daily smoking volume, the type of smoking, the age of starting smoking and the depth of smoking inhalation. Tobacco control should comprehensively consider the specific characteristics of smoking, so as to prevent COPD.

Age at smoking initiation and smoking cessation influence the incidence of stroke in China: a 10-year follow-up study

Our study aimed to explore the correlation between age at smoking initiation and smoking cessation for the risk for stroke in China. We investigated 50,174 participants from one of the urban areas of China Kadoorie Biobank (CKB) Study. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) for association between smoking and incidence of stroke were estimated using Cox regression model. During a median of 10.7 years of follow-up, 4370 total stroke cases were documented. Among men, comparing current smokers to never smokers, the HR of total stroke for current smokers was 1.279 (95% CI, 1.134-1.443) for total stroke. The HRs of total stroke were 1.344 (1.151-1.570) for those started smoking at age less than 20 years, 1.254 (1.090-1.443) for those started smoking at age 20-30 years, and 1.205 (1.012-1.435) for those started smoking at age 30 year and above, with a dose-response relation (P for trend, 0.004). Comparing former smokers to current smokers, in the low pack-year group, those stopped smoking at age less than 65 years had a 18.2% decreased risk for total stroke (0.818; 0.673-0.994). The decreased risk was not found in those stopped smoking at age 65 years and above. Similar results were observed in the high pack-year group. In conclusion, we found that current smokers had a higher stroke risk than never smokers, and the risk increased with a younger age at smoking initiation. Smoking cessation can reduce the risk for stroke, especially could benefit from cessation at a younger age.

Association between frequency of dairy product consumption and hypertension: a cross-sectional study in Zhejiang Province, China

BACKGROUND

Hypertension, a well-known risk factor, contributes to millions of deaths from cardiovascular and renal diseases worldwide. However, evidence on the association between frequency of dairy product consumption and hypertension is inconsistent.

METHODS

The data for the present study are from the Tongxiang baseline dataset of the China Kadoorie Biobank prospective study. A total of 53,916 participants aged 30-79 years were included in the final analysis. Multivariable logistic regression was utilized to evaluate the association of dairy product consumption with hypertension, and multiple linear regression was conducted to assess the association of dairy product consumption with systolic and diastolic blood pressure.

RESULTS

Of the 53,916 participants, 2.6% reported consuming dairy products weekly, and 44.4% had prevalent hypertension. After adjusting for socio-demographic status, lifestyle factors, BMI, waist circumference, sleep duration and snoring, when compared with participants who never consumed dairy products, the odds ratios (95% CI) for hypertension among those consuming dairy products less than once per week, and ≥ 1 time per week were 0.85 (0.77-0.95) and 0.74 (0.65-0.84), respectively. The corresponding odds ratios (95% CI) for men were 0.85 (0.71-1.02) and 0.75 (0.61-0.92), respectively (P_trend = 0.001), and for women were 0.88 (0.76-1.01) and 0.77 (0.65-0.91), respectively. (P_trend < 0.001).

CONCLUSIONS

In this large epidemiological study, higher frequency of dairy product consumption is associated with significantly lower odds of hypertension among Chinese adults.

Association between sleep duration and hypertension in southwest China: a population-based cross-sectional study

OBJECTIVE

Hypertension is a major risk factor and cause of many non-communicable diseases in China. While there have been studies on various diet and lifestyle risk factors, we do not know whether sleep duration has an association to blood pressure in southwest China. This predictor is useful in low-resource rural settings. We examined the association between sleep duration and hypertension in southwest China.

DESIGN

Population-based cross-sectional study.

SETTING

This study was part of the baseline survey of a large ongoing prospective cohort study, the China Kadoorie Biobank. Participants were enrolled in 15 townships of Pengzhou city in Sichuan province during 2004-2008.

PARTICIPANTS

55 687 participants aged 30-79 years were included. Sleep duration was assessed by a self-reported questionnaire.

MAIN OUTCOME MEASURES

Hypertension was defined as systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure ≥90 mm Hg, or prior physician-diagnosed hypertension in hospitals at the township (community) level or above.

RESULTS

The prevalence of hypertension was 25.17%. The percentages of subjects with sleep durations of <6, 6, 7, 8 and ≥9 hours were 17.20%, 16.14%, 20.04%, 31.95% and 14.67%, respectively. In multivariable-adjusted analyses, the increased ORs of having hypertension were across those who reported ≥9 hours of sleep (men: 1.16, 95% CI 1.04 to 1.30; women: 1.19, 95% CI 1.08 to 1.32; general population: 1.17, 95% CI 1.08 to 1.26). The odds of hypertension was relatively flat until around 6.81 hours of sleep duration and then started to increase rapidly afterwards in subjects and a J-shaped pattern was observed. There was a U-shaped relationship between sleep duration and hypertension in females.

CONCLUSION

Long sleep duration was significantly associated with hypertension and a J-shaped pattern was observed among rural adults in southwest China, independent of potential confounders. However, this association was not obvious between short sleep duration and hypertension.

Regional economic development, household income, gender and hypertension: evidence from half a million Chinese

BACKGROUND

Hypertension may be influenced by multiple factors, including social and individual determinants. Regional and individual economic disparity in China is closely associated with such factors that may give rise to diverse health outcomes. This study examines the relationship between regional economic development, household income, gender and hypertension prevalence in China.

METHODS

This study utilized data from the China Kadoorie Biobank (CKB), a population-based study on half a million Chinese adults from 10 geographically distinct regions. Hypertension was identified by a measured systolic blood pressure/diastolic blood pressure ≥ 140/90 mmHg or receiving treatment. Regional economic development was inferred from GDP per capita at the time of the study. A logistic regression based method was used in calculating the prevalence of hypertension in different household income, regional economic development, and gender groups, adjusting for demographic, social-economic and lifestyle factors.

RESULTS

The prevalence of hypertension was the lowest in the medium GDP per capita areas in both male (31.62, 95% CI: 31.26-31.98%) and female (22.85, 95% CI: 22.50-23.19%) as compared to that in the low GDP per capita regions (male: 32.75, 95% CI 32.41-33.08%; female: 32.12, 95% CI: 31.78-32.47%) and high GDP per capita areas (male: 39.74, 95% CI: 39.33-40.16%; female: 35.19, 95% CI: 34.74-35.65%). There was an inverse relationship between hypertension and household income in the low and high GDP areas and an U-shaped association in the medium GDP per capita areas. Higher hypertension prevalence was observed in males across all GDP per capita areas. The negative correlation between hypertension and household income (across all GDP per captia areas) was stronger in females than in males.

CONCLUSIONS

The present study underlined the important influence of regional economic development, household income and gender on hypertension. Interventions for hypertension prevention and management should take into consideration the influence of sex difference and socioeconomic disparities at both micro- and macro- levels, in addition to a person-centered approach.

Independent and interactive associations of heart rate and body mass index or blood pressure with type 2 diabetes mellitus incidence: A prospective cohort study

AIMS/INTRODUCTION

An elevated heart rate has been reported to be associated with an increased incidence of type 2 diabetes mellitus. We investigated whether heart rate independently and interactively with body mass index or blood pressure was associated with the incidence of type 2 diabetes mellitus in a rural Chinese population.

MATERIALS AND METHODS

We measured the association between heart rate and type 2 diabetes mellitus in the Tongxiang China Kadoorie Biobank prospective cohort study using Cox proportional hazard models. Analyses included 53,817 participants without any history of diabetes, cancer, cardiovascular or rheumatic heart disease at baseline. Incident type 2 diabetes mellitus cases were identified through linkage with established Disease Registries and the China National Health Insurance System.

RESULTS

After a mean follow-up period of 6.9 years, 1,766 people had developed type 2 diabetes mellitus with an incidence of 4.75 per 1,000 person-years. Multivariable-adjusted hazard ratios and for type 2 diabetes mellitus across increasing quintiles of heart rate were 1.00 (reference), 1.24 (95% confidence interval [CI] 1.05-1.45), 1.21 (95% CI 1.03-1.41), 1.24 (95% CI 1.05-1.47) and 1.49 (95% CI 1.28-1.74), respectively, with a Ptrend  <0.001. This relationship was particularly evident among non-overweight/obese participants. A significant interaction between heart rate and body mass index on incident type 2 diabetes mellitus was observed with a P for interaction = 0.005.

CONCLUSIONS

Elevated heart rate is independently, in interaction with a higher body mass index, associated with a higher incidence of type 2 diabetes mellitus.

[Prevalence of 'healthy lifestyle' in Chinese adults]

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.

[Relationship between educational level and long-term changes of body weight and waist circumference in adults in China]

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.

Age at natural menopause and associated factors in adult women: Findings from the China Kadoorie Biobank study in Zhejiang rural area

Objectives

To investigate the factors associated with age at natural menopause in a large population of Chinese adult women.

Methods

This cross-sectional study was part of the baseline survey of China Kadoorie Biobank in Zhejiang Province. A total of 17,076 postmenopausal women were included in the present study. Relevant data of socio-demographic, lifestyle, dietary and reproductive characteristics were collected. Multinomial logistic regression models were used to examine the associated factors of age at natural menopause with adjusted odds ratios (ORs) and their 95% confidence intervals (CIs) were reported.

Results

The mean age at natural menopause was 48.94 years, with 3.40% of the women experienced premature menopause and 6.75% early menopause. Younger age, higher education, consumption of meat (1–3 days per week) and increased parity were associated with late menopause. Current smoking, underweight, higher physical activity, consumption of sea food (1–3 days per week), fresh eggs (≥4 days per week), fresh fruits (≥1 day per week), taking vitamins, experiencing severe food shortage, earlier age at menarche and older age at first birth were associated with earlier age at natural menopause.

Conclusions

These results suggest that certain factors involved with socio-demographic, lifestyle, dietary and reproductive characteristics are related to the age at natural menopause in Chinese women.