J Chen

Seasonal variation in blood pressure and its relationship with outdoor temperature in 10 diverse regions of China: the China Kadoorie Biobank.

Objectives: Mean blood pressure varies moderately with outdoor air temperature in many western populations. Substantial uncertainty exists, however, about the strength of the relationship in other populations and its relevance to age, adiposity, medical treatment, climate and housing conditions. Methods: To investigate the relationship of blood pressure with season and outdoor temperature, we analysed cross-sectional data from the China Kadoorie Biobank study of 506u200a673 adults aged 30–79 years recruited from 10 diverse urban and rural regions in China. Analyses related mean blood pressure – overall and in various subgroups – to mean local outdoor temperature. Results: The mean difference in SBP between summer (June–August) and winter (December–February) was 10u200ammHg overall, and was more extreme, on average, in rural than in urban areas (12 vs. 8u200ammHg; P for interaction <0.0001). Above 5°C, SBP was strongly inversely associated with outdoor temperature in all 10 areas studied, with 5.7 (SE 0.04)u200ammHg higher SBP per 10°C lower outdoor temperature. The association was stronger in older people and in those with lower BMI. At lower temperatures, there was no evidence of an association among participants who reported having central heating in their homes. Conclusion: Blood pressure was strongly inversely associated with outdoor temperature in Chinese adults across a range of climatic conditions, although access to home central heating appeared to remove much of the association during the winter months. Seasonal variation in blood pressure should be considered in the clinical management of hypertension.

The Burden of Hypertension and Associated Risk for Cardiovascular Mortality in China

IMPORTANCEnHypertension is a leading cause of premature death in China, but limited evidence is available on the prevalence and management of hypertension and its effect on mortality from cardiovascular disease (CVD).nnnOBJECTIVESnTo examine the prevalence, diagnosis, treatment, and control of hypertension and to assess the CVD mortality attributable to hypertension in China.nnnDESIGN, SETTING AND PARTICIPANTSnThis prospective cohort study (China Kadoorie Biobank Study) recruited 500 223 adults, aged 35 to 74 years, from the general population in China. Blood pressure (BP) measurements were recorded as part of the baseline survey from June 25, 2004, to August 5, 2009, and 7028 deaths due to CVD were recorded before January 1, 2014 (mean duration of follow-up: 7.2 years). Data were analyzed from June 9, 2014, to July 17, 2015.nnnEXPOSURESnPrevalence and diagnosis of hypertension (systolic BP ≥140 mm Hg, diastolic BP ≥90 mm Hg, or receiving treatment for hypertension) and treatment and control rates overall and in various population subgroups.nnnMAIN OUTCOMES AND MEASURESnCox regression analysis yielded age- and sex-specific rate ratios for deaths due to CVD comparing participants with and without uncontrolled hypertension, which were used to estimate the number of CVD deaths attributable to hypertension.nnnRESULTSnThe cohort included 205 167 men (41.0%) and 295 056 women (59.0%) with a mean (SD) age of 52 (10) years for both sexes. Overall, 32.5% of participants had hypertension; the prevalence increased with age (from 12.6% at 35-39 years of age to 58.4% at 70-74 years of age) and varied substantially by region (range, 22.7%-40.7%). Of those with hypertension, 30.5% had received a diagnosis from a physician; of those with a diagnosis of hypertension, 46.4% were being treated; and of those treated, 29.6% had their hypertension controlled (ie, systolic BP <140 mm Hg; diastolic BP <90 mm Hg), resulting in an overall control rate of 4.2%. Even among patients with hypertension and prior CVD, only 13.0% had their hypertension controlled. Uncontrolled hypertension was associated with relative risks for CVD mortality of 4.1 (95% CI, 3.7-4.6), 2.6 (95% CI, 2.4-2.9) and 1.9 (95% CI, 1.8-2.0) at ages 35 to 59, 60 to 69, and 70 to 79 years, respectively, and accounted for about one-third of deaths due to CVD (approximately 750u202f000) at 35 to 79 years of age in 2010.nnnCONCLUSIONS AND RELEVANCEnAbout one-third of Chinese adults in this national cohort population had hypertension. The levels of diagnosis, treatment, and control were much lower than in Western populations, and were associated with significant excess mortality.

Adherence to Healthy Lifestyle and Cardiovascular Diseases in the Chinese Population.

BACKGROUNDnAdherence to a combination of healthy lifestyle factors has been related to a considerable reduction of cardiovascular risk in white populations; however, little is known whether such associations persist in nonwhite populations like the Asian population.nnnOBJECTIVESnThis study aimed to examine the associations of a combination of modifiable, healthy lifestyle factors withxa0the risks of ischemic cardiovascular diseases and estimate the proportion of diseases that could potentially be prevented by adherence to these healthy lifestyle patterns.nnnMETHODSnThis study examined the associations of 6 lifestyle factors with ischemic heart disease and ischemic stroke (IS) in the China Kadoorie Biobank of 461,211 participants 30 to 79 years of age who did not have cardiovascular diseases,xa0cancer, or diabetes at baseline. Low-risk lifestyle factors were defined as nonsmoking status or having stopped smoking for reasons other than illness, alcohol consumption ofxa0<30 g/day, a median or higher level of physical activity, axa0diet rich in vegetables and fruits and limited in red meat, a body mass index of 18.5 to 23.9 kg/m2, and a waist-to-hip ratioxa0<0.90 for men andxa0<0.85 for women.nnnRESULTSnDuring a median of 7.2 years (3.3 million person-years) of follow-up, this study documented 3,331 incident major coronary events (MCE) and 19,348 incident ISs. In multivariable-adjusted analyses, current nonsmoking status, light to moderate alcohol consumption, high physical activity, a diet rich in vegetables and fruits and limited in red meat, and low adiposity were independently associated with reduced risks of MCE and IS. Compared with participants withoutxa0any low-risk factors, the hazard ratio for participants withxa0≥4 low-risk factors was 0.42 (95% confidence interval: 0.34 to 0.52) for MCE and 0.61 (95% confidence interval: 0.56 to 0.66) for IS. Approximately 67.9% (95%xa0confidence interval: 46.5% to 81.9%) of the MCE and 39.1% (95% confidence interval: 26.4% to 50.4%) of the ISxa0cases were attributable to poor adherence to healthy lifestyle.nnnCONCLUSIONSnAdherence to healthy lifestyle may substantially lower the burden of cardiovascular diseases in Chinese.

Blood pressure in relation to general and central adiposity among 500 000 adult Chinese men and women

Background: Greater adiposity is associated with higher blood pressure. Substantial uncertainty remains, however, about which measures of adiposity most strongly predict blood pressure and whether these associations differ materially between populations. Methods: We examined cross-sectional data on 500u2009000 adults recruited from 10 diverse localities across China during 2004–08. Multiple linear regression was used to estimate the effects on systolic blood pressure (SBP) of general adiposity [e.g. body mass index (BMI), body fat percentage, height-adjusted weight] vs central adiposity [e.g. waist circumference (WC), hip circumference (HC), waist-hip ratio (WHR)], before and after adjustment for each other. The main analyses excluded those reported taking any antihypertensive medication, and were adjusted for age, region and education. Results: The overall mean [standard deviation (SD)] BMI was 23.6 (3.3)u2009kg/m2 and mean WC was 80.0 (9.5)u2009cm. The differences in SBP (men/women, mmHg) per 1SD higher general adiposity (height-adjusted weight: 6.6/5.6; BMI: 5.5/4.9; body fat percentage: 5.5/5.0) were greater than for central adiposity (WC: 5.0/4.3; HC: 4.8/4.1; WHR: 3.7/3.2), with a 10u2009kg/m2 greater BMI being associated on average with 16 (men/women: 17/14) mmHg higher SBP. The associations of blood pressure with measures of general adiposity were not materially altered by adjusting for WC and HC, but those for central adiposity were significantly attenuated after adjusting for BMI (WC: 1.1/0.7; HC: 0.3/−0.2; WHR: 0.6/0.6). Conclusion: In adult Chinese, blood pressure is more strongly associated with general adiposity than with central adiposity, and the associations with BMI were about 50% stronger than those observed in Western populations.

Fresh fruit consumption in relation to incident diabetes and diabetic vascular complications: A 7-y prospective study of 0.5 million Chinese adults.

Background Despite the well-recognised health benefits of fresh fruit consumption, substantial uncertainties remain about its potential effects on incident diabetes and, among those with diabetes, on risks of death and major vascular complications. Methods and findings Between June 2004 and July 2008, the nationwide China Kadoorie Biobank study recruited 0.5 million adults aged 30–79 (mean 51) y from ten diverse localities across China. During ~7 y of follow-up, 9,504 new diabetes cases were recorded among 482,591 participants without prevalent (previously diagnosed or screen-detected) diabetes at baseline, with an overall incidence rate of 2.8 per 1,000 person-years. Among 30,300 (5.9%) participants who had diabetes at baseline, 3,389 deaths occurred (overall mortality rate 16.5 per 1,000), along with 9,746 cases of macrovascular disease and 1,345 cases of microvascular disease. Cox regression yielded adjusted hazard ratios (HRs) associating each disease outcome with self-reported fresh fruit consumption, adjusting for potential confounders such as age, sex, region, socio-economic status, other lifestyle factors, body mass index, and family history of diabetes. Overall, 18.8% of participants reported consuming fresh fruit daily, and 6.4% never/rarely (non-consumers), with the proportion of non-consumers about three times higher in individuals with previously diagnosed diabetes (18.9%) than in those with screen-detected diabetes (6.7%) or no diabetes (6.0%). Among those without diabetes at baseline, higher fruit consumption was associated with significantly lower risk of developing diabetes (adjusted HR = 0.88 [95% CI 0.83–0.93] for daily versus non-consumers, p < 0.001, corresponding to a 0.2% difference in 5-y absolute risk), with a clear dose–response relationship. Among those with baseline diabetes, higher fruit consumption was associated with lower risks of all-cause mortality (adjusted HR = 0.83 [95% CI 0.74–0.93] per 100 g/d) and microvascular (0.72 [0.61–0.87]) and macrovascular (0.87 [0.82–0.93]) complications (p < 0.001), with similar HRs in individuals with previously diagnosed and screen-detected diabetes; estimated differences in 5-y absolute risk between daily and non-consumers were 1.9%, 1.1%, and 5.4%, respectively. The main limitation of this study was that, owing to its observational nature, we could not fully exclude the effects of residual confounding. Conclusion In this large epidemiological study in Chinese adults, higher fresh fruit consumption was associated with significantly lower risk of diabetes and, among diabetic individuals, lower risks of death and development of major vascular complications.

Sleep behavior and depression: Findings from the China Kadoorie Biobank of 0.5 million Chinese adults

Background Mixed results have shown the association between sleep behavior and depression, but evidence relating the joint effect of sleep duration and sleep disturbances is limited, especially in Chinese population. Methods A total of 512,891 adults aged 30–79 years from China Kadoorie Biobank (CKB) were included. Depression was defined by Composite International Diagnostic Inventory-short form (CIDI-SF). Sleep duration and sleep disturbances, including difficulty initiating and maintaining sleep (DIMS), early morning awakening (EMA), daytime dysfunction (DDF) and any sleep disturbances (ASD), were obtained by a self-reported questionnaire. Logistic regression was applied to examine the association between sleep behavior and depression. Results About 23.1% of participants reported short sleep duration (≤ 6 h), and 5.1% reported long sleep duration (> 9 h). Compared with normal sleep duration (7–9 h), both groups were associated greater likelihood of having depression (short sleep: OR = 2.32, 95%CI: 2.14–2.51; long sleep: OR = 1.56, 96%CI: 1.34–1.81). Participants reported sleep disturbances were significantly associated with depression (odds ratios ranged from 3.31 to 4.17). Moreover, the associations tended to be stronger for those who reported both abnormal sleep duration and sleep disturbances (p for interactions < 0.05), especially for those who slept long. Limitations The cross-sectional nature of the study design limits the interpretation of the results. Conclusions Abnormal sleep duration and sleep disturbances were associated with depression. The associations were stronger for abnormal sleep duration accompanied with sleep disturbances, especially for a long duration. More attention should be paid on these persons in clinical practice.

Tea consumption and risk of ischaemic heart disease.

Objective To prospectively examine the association between tea consumption and the risk of ischaemic heart disease (IHD). Methods Prospective study using the China Kadoorie Biobank; participants from 10 areas across China were enrolled during 2004–2008 and followed up until 31 December 2013. After excluding participants with cancer, heart disease and stroke at baseline, the present study included 199u2005293 men and 288u2005082 women aged 30–79u2005years at baseline. Information on IHD incidence was collected through disease registries and the new national health insurance databases. Results During a median follow-up of 7.2u2005years, we documented 24u2005665 (7.19 cases/1000 person-years) incident IHD cases and 3959 (1.13 cases/1000 person-years) major coronary events (MCEs). Tea consumption was associated with reduced risk of IHD and MCE. In the whole cohort, compared with participants who never consumed tea during the past 12u2005months, the multivariable-adjusted HRs and 95% CIs for less than daily and daily tea consumers were 0.97 (0.94 to 1.00) and 0.92 (0.88 to 0.95) for IHD, 0.92 (0.85 to 1.00) and 0.90 (0.82 to 0.99) for MCE. No linear trends in the HRs across the amount of tea were observed in daily consumers for IHD and MCE (PLinear >0.05). The inverse association between tea consumption and IHD was stronger in rural (PInteraction 0.006 for IHD, <0.001 for MCE), non-obese (PInteraction 0.012 for MCE) and non-diabetes participants (PInteraction 0.004 for IHD). Conclusions In this large prospective study, daily tea consumption was associated with a reduced risk of IHD.

Association of Physical Activity With Risk of Major Cardiovascular Diseases in Chinese Men and Women.

Importance In China, the patterns and levels of physical activity differed from those in high-income countries. Substantial uncertainty remains about the relevance, both qualitatively and quantitatively, of domain-specific physical activity for cardiovascular disease (CVD) subtypes in Chinese adults. Objective To assess the shape and strength of the associations of total, occupational, and nonoccupational physical activity with CVD subtypes in Chinese men and women. Design, Setting, and Participants This population-based prospective cohort study in 10 (5 urban, 5 rural) areas across China included 487 334 adults who were aged 30 to 79 (mean 51) years with no prior CVD history when enrolled from June 2004 to July 2008. Exposures Self-reported total, occupational, and nonoccupational physical activity, quantified as metabolic equivalent of task hours per day (MET-h/d) based on the type, frequency, and duration of specific activities. Main Outcomes and Measures Major vascular events (nu2009=u200936 184) and their components, including major coronary events (nu2009=u20095082), ischemic stroke (nu2009=u200925 647), intracerebral hemorrhage (nu2009=u20095252), and CVD death (nu2009=u20098437). Cox regression yielded adjusted hazard ratios for each disease that was associated with physical activity. Results Of the 487 334 study participants, 287 527 (59%) were women and the mean (SD) age was 51 (10.5) years. The overall mean (SD) total physical activity was 21.5 (12.8) MET-h/d, mainly from occupational activity, especially among men (75% vs 50% in women). Total physical activity was inversely associated with the risk of major vascular events, with the adjusted hazard ratio that compared the top vs bottom quintiles of physical activity being 0.77 (95% CI, 0.74-0.80). Throughout the range of total physical activity studied, the association with CVD with each 4 MET-h/d higher usual total physical activity (approximately 1 hour of brisk walking per day) associated with a 6% (95% CI, 5%-7%) lower risk of major vascular events, and a 9%, 5%, 6%, and 12% lower risk of major coronary events, ischemic stroke, intracerebral hemorrhage, and CVD death, respectively. The strength of the associations was similar and independent of each other for occupational and nonoccupational physical activity. However, for occupational physical activity, the associations with CVD subtypes were greatly attenuated above 20 MET-h/d, especially for intracerebral hemorrhage. The associations of total physical activity with major vascular events were similar among men and women and across different levels of sedentary leisure time but were much weaker among individuals with high blood pressure. Conclusions and Relevance Among Chinese adults, higher occupational or nonoccupational physical activity was associated with significantly lower risks of major CVD.

SEASONAL VARIATION IN BLOOD PRESSURE AMONG CHINESE ADULTS: THE KADOORIE BIOBANK STUDY OF 0.5 MILLION PEOPLE IN CHINA

Introduction Seasonal variation in blood pressure and its association with outdoor air temperature has been reported in several studies. However, large population-based studies are few and data from developing countries such as China are limited. Methods Cross-sectional data from the Kadoorie Biobank Study were used to relate seasonal variation in systolic blood pressure (SBP) to outdoor air temperature in 510u2008000 Chinese adults aged 30–79 recruited during 2004–2008 at 10 widely separated study sites. Analyses related mean SBP—overall and in subgroups of the population—to mean local air temperature on the day of recruitment. Results SBP was strongly inversely associated with temperature within all 10 areas studied, at least above 5°C, with a mean rise of 5.7 (SE 0.04) mmu2002Hg per 10°C fall in outdoor temperature. The mean difference in SBP between summer (Jun–Aug) and winter (Dec–Feb) was 10u2005mmu2002Hg, and was more extreme in rural than in urban areas (12 vs 8u2005mmu2002Hg). The association was slightly stronger in older people, at lower body mass index, and in people taking antihypertensive medications. At low temperature the association was greatly attenuated in participants with central heating in their home. Conclusion SBP is strongly inversely associated with outdoor temperature in Chinese adults, across a range of climatic exposures. Season or temperature and access to central heating should be considered a source of variation in epidemiological studies of blood pressure and in the clinical management of hypertension.

ADIPOSITY AND ITS CONTRIBUTION TO INDIVIDUAL AND REGIONAL DIFFERENCES IN BLOOD PRESSURE: THE KADOORIE BIOBANK STUDY OF 0.5 MILLION PEOPLE IN CHINA

Introduction Raised blood pressure (BP) is a leading cause of premature death in China, but its determinants are not well understood. One likely determinant, adiposity, is increasing rapidly in much of China. We assessed the extent to which differences in BP can be accounted for by differences in body mass index (BMI) and in waist circumference (WC). Methods We examined cross-sectional data from >510u2008000 adults aged 30–79 recruited from five rural and five urban areas in China. Height, weight, systolic BP and WC were measured for all participants. Means and associations of SBP with age, BMI and WC were estimated in men and women separately. Results The population means (SD) of SBP and BMI in men were 132 (20)u2005mmu2002Hg and 23.4 (3.2)u2005kg/m2. Age-adjusted area means of SBP ranged from 126 to 136u2005mmu2002Hg (F=77 p<0.0001, R2=0.09), and area means of BMI ranged from 22.0u2005kg/m2 to 25.4u2005kg/m2. Overall, and within each area, SBP was approximately linearly associated with BMI: overall +17u2005mmu2002Hg SBP per +10u2005kg/m2 BMI. However, further adjusting SBP for BMI only accounted for an additional 7% of individual variation in SBP, and had little effect on differences between area means of SBP (F=30 p<0.0001). Despite lower BMI in rural vs urban areas (22.7 vs 24.3u2005kg/m2), mean SBP was higher in rural areas (132 vs 131u2005mmu2002Hg, p<0.0001). Similar patterns were found for WC, and in women. Conclusions SBP is consistently associated with adiposity in individuals, but differences in adiposity do not account for most of the differences in SBP between individuals or between areas.