Body mass index and risk of stroke among Chinese men and women.

OBJECTIVE: The relationship between body mass index (BMI) and stroke incidence and mortality remains controversial, particularly in Asian populations. METHODS: We conducted a prospective cohort study in a nationally representative sample of 169,871 Chinese men and women age 40 years or older. Data on body weight was obtained at baseline examination in 1991 using a standard protocol. Follow-up evaluation was conducted in 1999 to 2000, with a response rate of 93.4%. RESULTS: After excluding those participants with missing body weight or height values, 154,736 adults were included in the analysis. During a mean follow-up of 8.3 years, 7,489 strokes occurred (3,924 fatal). After adjustment for age, gender, physical inactivity, urbanization, geographic variation, cigarette smoking, diabetes, and education, compared with participants of normal weight (BMI 18.5-24.9), relative hazard (95% confidence interval) of incident stroke was 0.86 (0.80-0.93) for participants who were underweight (BMI < 18.5), 1.43 (1.36-1.52) for those who were overweight (BMI 25-29.9), and 1.72 (1.55-1.91) for those who were obese (BMI > or = 30). The corresponding relative hazards were 0.76 (0.66-0.86), 1.60 (1.48-1.72), and 1.89 (1.66-2.16) for ischemic stroke and 1.00 (0.89-1.13), 1.18 (1.06-1.31), and 1.54 (1.27-1.87) for hemorrhagic stroke. For stroke mortality, the corresponding relative hazards were 0.94 (0.86-1.03), 1.15 (1.05-1.25), and 1.47 (1.26-1.72). Linear trends were significant for all outcomes (p < 0.0001). INTERPRETATION: These results suggest that elevated BMI increases the risk of both ischemic and hemorrhagic stroke incidence, and stroke mortality in Chinese adults.

Alcohol consumption and risk for stroke among Chinese men.

OBJECTIVE: Stroke is a leading cause of death and long-term disability in China. The objective of this study was to examine the relation between alcohol consumption and risk for stroke among Chinese men. METHODS: We conducted a prospective cohort study among 64,338 Chinese men aged > or = 40 years who were free of stroke at baseline. Data on frequency and type of alcohol consumed were collected at the baseline examination in 1991 using a standard protocol. Follow-up evaluation was conducted in 1999 to 2000, which included determining vital status, interviewing participants or proxies, and obtaining hospital and medical records for incident and fatal strokes. RESULTS: Over the course of 493,351 person-years of follow-up, we documented 3,434 incident strokes (1,848 stroke deaths). After adjustment for age, body mass index, physical activity, urbanization (urban vs rural), geographic variation (north vs south), cigarette smoking, history of diabetes, and education, compared with nondrinkers, relative risk (95% confidence interval) of incident stroke was 0.92 (0.80-1.06) for participants consuming 1 to 6 drinks/week, 1.02 (0.93-1.13) for those consuming 7 to 20 drinks/week, 1.22 (1.07-1.38) for those consuming 21 to 34 drinks/week, and 1.22 (1.08-1.37) for those consuming 35 or more drinks per week (p for linear trend < 0.0001). The corresponding relative risks for stroke mortality were 0.93 (0.76-1.14), 0.98 (0.85-1.13), 1.15 (0.95-1.38), and 1.30 (1.11-1.52), respectively (p for linear trend = 0.0004; p for quadratic trend = 0.03). INTERPRETATION: These results suggest that heavy alcohol drinking may increase the risk for stroke in Chinese men and should be the target of strategies for prevention.

Incidence and predictors of hypertension over 8 years among Chinese men and women.

OBJECTIVE: To determine the 8-year incidence of hypertension and its risk factors among Chinese adults. METHODS: A population-based sample of 10,525 Chinese adults aged > or = 40 years and free from hypertension at baseline was followed up from 1991 to 1999-2000. Incident hypertension was defined as systolic pressure > or = 140 mmHg, diastolic pressure > or = 90 mmHg, or current use of antihypertensive medication. RESULTS: Over a mean of 8.2 years of follow-up, 28.9% of men and 26.9% of women developed hypertension. Among men, independent predictors of incident hypertension were baseline age [relative risk (RR) per 5 years: 1.10; 95% confidence interval (CI): 1.07, 1.13], living in urban regions versus rural regions (RR: 0.74; 95% CI: 0.64, 0.85), alcohol drinking versus non-drinking (RR: 1.13; 95% CI: 1.02, 1.24), prehypertension versus normotension (RR: 1.70; 95% CI: 1.53, 1.88), heart rate (RR of third versus first tertile: 1.27; 95% CI: 1.13, 1.44), body mass index (RR of third versus first tertile: 1.28; 95% CI: 1.12, 1.46) and low versus high physical activity (RR: 1.27; 95% CI: 1.10, 1.47). Results were similar for women, with current smoking in place of alcohol drinking and opposite results for region. The population-attributable risk of modifiable risk factors was between 25 and 50%. CONCLUSIONS: These data indicate that the incidence of hypertension is high among these Chinese adults, and suggest that 25-50% of new hypertension cases could be prevented with risk factor modification. Given the excess cardiovascular mortality associated with hypertension, these data call for urgent improvements in hypertension prevention and control programs in China.

Are waist circumference and body mass index independently associated with cardiovascular disease risk in Chinese adults?

BACKGROUND: In Western populations, waist circumference (WC) is more predictive of cardiovascular disease (CVD) risk than is body mass index (BMI). It is unclear whether the same is true in Asian populations. OBJECTIVE: The objective was to examine the independent effects of WC and BMI on CVD risk factors in China. DESIGN: CVD risk factors, BMI, and WC were measured in a nationally representative cross-sectional study of 15 540 Chinese adults aged 35-74 y. RESULTS: Higher WC tertiles were associated with higher blood pressure and higher cholesterol, triacylglycerol, and glucose concentrations within each tertile of BMI and vice versa. In men, the odds of hypertension, dyslipidemia, and the metabolic syndrome (MS) increased with successive WC tertiles (1.0, 1.1, and 1.8, respectively, for hypertension; 1.0, 1.4, and 2.0, respectively, for dyslipidemia; and 1.0, 2.3, and 4.8, respectively, for MS; P for trend < 0.001 for all), even after adjustment for BMI. Similarly, the odds of hypertension, dyslipidemia, and MS increased with successive BMI tertiles (1.0, 1.5, and 2.6, respectively, for hypertension; 1.0, 1.3, and 1.8, respectively, for dyslipidemia; 1.0, 1.3, and 2.9, respectively for MS; P for trend < 0.001 for all), even after adjustment for WC. However, BMI tertiles were not associated with the odds of diabetes after adjustment for WC (P for trend = 0.67), whereas tertiles of WC were significantly associated with the odds of diabetes after adjustment for BMI (1.0, 1.6, and 2.1, respectively; P for trend = 0.002). The results were similar in women. CONCLUSIONS: These data show that WC adds additional risk information to that of BMI in Chinese adults. Measurement of both WC and BMI in Chinese adults may enhance CVD risk stratification.

Alcohol consumption and risk of coronary heart disease among Chinese men.

BACKGROUND: Observational studies suggest that moderate alcohol consumption may lower risk of myocardial infarction (MI) and coronary heart disease (CHD); yet, evidence for this comes almost entirely from Western populations. METHODS: We conducted a prospective cohort study in 64,597 Chinese men aged > or = 40 years who were free of clinical CHD at baseline examination. Data on frequency and type of alcohol consumed were collected at the baseline examination in 1991 using a standard protocol. Follow-up evaluation was conducted in 1999-2000, with a response rate of 94%. RESULTS: Over 494,084 person-years of follow-up, we documented 725 (361 fatal) incident MI and 976 (588 fatal) incident CHD events. After stratification by province to account for multi-stage sampling design and adjustment for age, education, physical activity, cigarette smoking, body mass index, systolic blood pressure, urbanization (urban vs. rural), geographic variation (north vs. south) and history of diabetes, relative risk (95% confidence interval) of MI was 0.93 (0.70-1.24) for participants consuming 1 to 6 drinks/week, 0.66 (0.54-0.82) for those consuming 7 to 34 drinks/week, and 0.58 (0.41-0.81) for those consuming > or = 35 drinks/week (p for linear trend <0.0001) compared to non-drinkers. The corresponding relative risks for CHD events were 0.99 (0.77-1.27), 0.67 (0.56-0.81), and 0.58 (0.44-0.78), respectively (p for linear trend <0.0001). CONCLUSION: Alcohol consumption may be related to lower risk of MI and CHD in middle-aged and older Chinese men. However, heavy alcohol consumption may lead to increased mortality from other causes; therefore, the implications of these findings should be interpreted cautiously.

Trends in overweight and obesity in Chinese adults: between 1991 and 1999-2000.

OBJECTIVE: The aim of this study was to evaluate trends in BMI and the prevalence of overweight (BMI > or = 25 kg/m(2)) and obesity (BMI > or = 30 kg/m(2)) between 1991 and 1999-2000 among Chinese adults. METHODS AND PROCEDURES: In this study, two population-based samples of Chinese adults aged between 45 and 79 years (n = 7,858 during each period), and comparable in the distributions of age, gender, degree of urbanization, and region (North/South) were used. Height and weight were measured using identical procedures at each period, and BMI was calculated as weight (in kilogram) divided by height (in square meter). RESULTS: From 1991 to 1999-2000, the mean BMI increased from 21.8 to 23.4 kg/m(2) among men and from 21.8 to 23.5 kg/m(2) among women (each P < 0.001). Among men, the prevalence of overweight and obesity increased from 9.6 and 0.6%, respectively, in 1991 to 20.0 and 3.0%, respectively, in 1999-2000 (each P < 0.001). Among women, the prevalence of overweight and obesity increased from 14.5 and 1.8%, respectively, in 1991 to 26.5 and 5.2%, respectively, in 1999-2000 (each P < 0.001). The prevalence of overweight and obesity increased in all age groups, in rural and urban areas, and in North and South China, with greater relative increases in obesity among older age groups, South China, and rural areas (P interaction < 0.05). DISCUSSION: Overweight and obesity increased tremendously during the 1990s in China. These data underscore the need for national programs in weight maintenance and reduction, to prevent obesity-related outcomes in China.

Factors associated with hypertension awareness, treatment, and control in a representative sample of the chinese population.

We studied factors associated with awareness, treatment, and control of hypertension (systolic/diastolic blood pressure measurements >/=140/90 mm Hg, respectively, and/or current drug treatment for hypertension) in a representative sample of the Chinese population (n=15 838). Awareness, treatment, and control were defined by self-report of a hypertension diagnosis, self-report of current antihypertensive medication use, and a systolic and diastolic blood pressure <140/90 mm Hg, respectively. Higher awareness (OR; 95% CI) was noted for persons who were married (1.43; 1.09, 1.88) and had their blood pressure measured in 1 year (47.4; 31.7, 70.4) or 1 to 5 years (11.4; 7.09, 18.2) preceding their study visit; lower awareness was found among men (0.62; 0.52, 0.74) and current smokers (0.79; 0.63, 0.99). Among those aware of their hypertension, treatment was more common (OR; 95% CI) at higher income (1.24 [0.87, 1.75], 1.46 [1.01, 2.12] and 1.58 [1.06, 2.37] for increasing versus the lowest quartile of income) and for participants who had their blood pressure measured during the preceding year (3.87; 1.89, 7.93) and was less common among men (0.76; 0.59, 0.98). Controlled hypertension was more common (OR; 95% CI) among persons whose blood pressure had been measured 1 year (4.93; 1.51, 16.1) and 1 to 5 years (14.8; 3.63, 60.5) prior to their study visit and, among persons aware of their hypertension diagnosis, those who undertook lifestyle modification (1.59; 1.11, 2.27). These data identify potential methods for improving blood pressure control in China through the identification, follow-up, and lifestyle modification of persons with high blood pressure.