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Chinese Heart Disease

Chinese Heart Disease

  • China, with a rapidly developing economy (currently the second largest) and the most populous nation in the world, experienced more than a doubling of CVD (cardiovascular disease) mortality from 1985 to 2005. More than 230 million Chinese have some form of CVD, resulting in 3 million deaths.1
  • Despite very high rates of smoking (men 62%), Chinese had some of the lowest rates of heart disease (less than a third of the US) (Figure 073). However, because of the sheer size of the population, 2 million heart attacks occur annually (compared to 7 million strokes).

  • China is home to one-fifth of the world’s population. Since the 1950’s life expectancy in China has more than doubled from 35 to 72 years. The proportion of persons >65 years in the total population will double from 7% to 14% between 2010 and 2030.1
  • According to recent (2010) estimates, due to aging and population growth, the annual CVD events in China is projected to increase by >50% between 2010 to 2030, even if risk factors stay at year 2000 levels; This would result in 39 million CAD events and 130 million strokes (total 169 million).1
  • It is projected that unfavorable trends in blood pressure (8 mm Hg increase) cholesterol (22 mg/dl increase), body mass index, and obesity will continue with favorable trend or actual decrease in smoking in the coming decades. This would result in a predicted increase of more than 26 million CVD events and 8 million CVD deaths over the 20-year period (from 2010 to 2030). The small decline in active smoking in Chinese men would only partially offset the cardiovascular consequences of increasing blood pressure, total cholesterol, diabetes, or obesity.   
  • The unfavorable changes in risk factors would result in greater increase in ischemic stroke than heart attacks. Chinese have three times more stroke than heart attacks with an annual incidence of 7 million strokes compared to 2 million heart attacks. In 2001, stroke resulted in 18% of all Chinese deaths compared with 8% from heart disease.2
  • Aging of the population is inevitable, but the projected additional impact of unfavorable risk factors is potentially reversible. National policy aimed at controlling blood pressure, smoking, and other risk factors would counteract the expected future CVD epidemic in China. Even if other adverse risk factor trends continue unabated, national policy targeted toward aggressive blood pressure lowering or tobacco control policy could save 2.9 to 5.7 million lives during the next 20 years.2
  •  As is true for most developing countries, low socioeconomic status (SES) is an important barrier for Chinese patients to receive the recommended treatments in secondary prevention. For example, compared with the patients with the highest SES, the patients with the lowest SES had a 43% lower treatment rate for aspirin, a 76% lower rate for clopidogrel, a 70% lower rate for statins, and a 70% lower rate for beta-blockers after adjustment for various cofactors.3
  • In fact, China is moving in the right direction, as major prevention programs are being implemented that target raising public awareness, educating and empowering the population, and strengthening health care systems to better manage CVD risk factors, such as tobacco smoking and hypertension.3
  • Diabetes prevalence among people with heart disease was 23% in mainland China, approximately two-fold lower than the other regions. Obesity and other risk factors progressively worsen as patients move from mainland China to Hong Kong/Singapore/Taiwan and overseas.
  • Despite similar medication use, risk factor control and CVD outcomes were significantly different. The magnitude of these changes is larger than formerly estimated, suggesting population differences in CVD risk and disease prevalence, likely to be more closely associated with lifestyle and cultural habits than genetic difference.4

Chinese Paradox                  

  • The low rate of heart disease despite high rates of smoking and hypertension among Chinese is called the Chinese paradox.5 The incidence and mortality from CAD in Chinese had been 5-fold lower than the U.S.5-7 In addition, the mortality rates among Chinese have been 3 to 4-fold lower than Asian Indians in many countries.8-10
  • The contemporary (2011) prevalence of risk factors are increasing but rates of cardiovascular disease remains low in China.14 
Contemporary prevalence of heart disease, stroke, and cardiovascular disease in China15
N=46 239 Coronary disease Stroke Cardiovascular disease
Male 0.74 1.07 1.78
Female 0.51 0.60 1.10

  • The hospitalization for CAD among Chinese Americans are 4-fold lower than whites and 6-fold lower than Asian Indians.11
  • The low rates of CAD in China are attributed to their highly anti-atherogenic lipid profile.6 The typical lipid levels in rural China are: TC 127 mg/dL; LDL 63 mg/dL; TG 100 mg/dL; HDL 44 mg/dL and TC/HDL ratio 2.9.12

Chinese Risk Factors

  • In Beijing, for every death prevented from advances in treatment of CVD, three deaths were produced as result of increases in major risk factors for CVD and diabetes. This may be equally true in India and other developing countries.1
  • A staggering 200 million Chinese have either high blood pressure or high blood cholesterol, and 350 million are current smokers. This high prevalence of risk factors can lead to future CVD events unless these risk factors are aggressively treated and controlled.
  • Hypertension is a stronger risk factor for stroke whereas high cholesterol is the strongest risk factor for heart disease. A projected 4 mm Hg increase in systolic blood pressure would result in 1.4 million CAD events and 11.4 million strokes, whereas a 22 mg/dl increase in TC would produce 5 million coronary events and 4.2 million strokes between 2010 and 2030. 1
  • Though male smoking prevalence has declined (>10% since the mid-1980s), 62% of Chinese men smoke actively, and at least 49% of nonsmokers (predominantly women) are exposed to passive smoking at home or at work.
  • Aggressively reducing active smoking in Chinese men to 20% prevalence in 2020 ( current smoking rate in the US) and 10% prevalence in 2030 or reducing mean systolic blood pressure by 4 mm Hg in men and women would counteract adverse trends in other risk factors in preventing cardiovascular events.
  • A one percentage point annual decline in active smoking in Chinese men would prevent almost 1.7 million “noncardiovascular disease” deaths, such as cancer and chronic obstructive lung disease deaths.1
  • The prevalence of diabetes has steadily increased among men and women in China and is now a substantial public health problem with more than 90 million adults with diabetes and nearly 150 million with prediabetes.1
  • Chinese surveys have documented consumption of more dietary fats, over nutrition, and less physical activity in recent years. Additionally, relatively few Chinese adults with dyslipidemia, high blood pressure, or diabetes are aware of these risk factors.1
  • Although hypertension, smoking, high cholesterol and diabetes are the major modifiable risk factors, these risk factors accounted for 60-70% of the CVD risk among Chinese. The remaining  30% to 40% of CVD events in both men and women could be due to air pollution and other aspects of urbanization such as decreased physical activity, atherogenic diet, and stress.3
  • Obesity is associated with metabolic risk factors. Body mass index (BMI), waist circumference, waist-hip ratio (WHR) and waist-height ratio (WHtR) are used to predict the risk of obesity related diseases.13
  • The appropriate cut-off values to predict the presence of multiple metabolic risk factors are 23 for BMI, in males and females. Those of waist circumference were 91cm and 87cm and WHtR is 0.51  for male and 0.53 for females.13 These values are substantially lower than those in Europids.

Sources

1. Moran A, Gu D, Zhao D, et al. Future Cardiovascular Disease in China: Markov Model and Risk Factor Scenario Projections From the Coronary Heart Disease Policy Model-China. Circ Cardiovasc Qual Outcomes. May 4 2010.

2. Gaziano J M. Global burden of cardiovascular disease. In: Braunwald E, ed. Pliladelphia, PA: Saunders; 2008.

3. Smith SC Jr, Zheng ZJ. The impending cardiovascular pandemic in China. Circ Cardiovasc Qual Outcomes. May 2010;3(3):226-227.

4. Chiu JF, Bell AD, Herman RJ, et al. Cardiovascular risk profiles and outcomes of Chinese living inside and outside China. Eur J Cardiovasc Prev Rehabil. Apr 27 2010.

5. Wu Z, Yao C, Zhao D, et al. Sino-MONICA Project: A collaborative study on trends and determinants in cardiovascular diseases in China, Part I: Morbidity and mortality monitoring. Circulation. 2001;103(3):462-468.

6. Yuan JM, Ross R, Wanh X, Gao Y, Henderson B, Yu M. Morbidity and mortality in relation to cigarette smoking in Shanghai, China: A prospective male cohort study. JAMA. 1996;275:1646-1650.

7. Chen CH, Chuang J, Kuo H, et al. A population-based epidemiological study of cardiovascular risk factors in Kinchen, Kinmen. Int J Epidemiol. 1995;48:75-88.

8. Woo KS, Chook P, Raitakari OT, McQuillan B, Feng JZ, Celermajer DS. Westernization of Chinese adults and increased subclinical atherosclerosis. Arterioscler Thromb Vasc Biol. 1999;19(10):2487-2493.

9. Anand S, Yusuf S. Ethnicity and cardiovascular disease. In: Yusuf S, ed. Evidenced Based cardiology. London: BMJ Books; 1998:329 – 352.

10. Hughes K. Coronary artery disease in Indians in Singapore. In: Sethi K, ed. Coronary artery disease in Indians – A Global perspective. Mumbai: Cardiological Society of India; 1998:56-62.

11. Klatsky  AL, Tekawa I, Armstrong MA, Sidney S. The risk of hospitalization for ischemic heart disease among Asian Americans in northern California. Am J Public Health. Oct 1994;84(10):1672-1675.

12. Chen J, Campbell T, Li J. Diet, Lifestyle, and Mortality in China, a study of the characteristics of 65 Chinese cantons. Oxford, UK: Oxford University Press; 1990.

13. Liu Y, Tong G, Tong W, Lu L, Qin X. Can body mass index, waist circumference, waist-hip ratio and waist-height ratio predict the presence of multiple metabolic risk factors in Chinese subjects? BMC Public Health. Jan 13 2011;11(1):35.

14. Yang ZJ., Liu J, Ge JP, Chen L, Zhao ZG, Yang WY. Prevalence of cardiovascular disease risk factor in the Chinese population: the 2007-2008 China National Diabetes and Metabolic Disorders Study. Eur Heart J. Jun 30 2011.

15. Bild DE, Detrano R, Peterson D, et al. Ethnic differences in coronary calcification: the Multi-Ethnic Study of Atherosclerosis (MESA). Circulation. Mar 15 2005;111(10):1313-1320.

 

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