Journal of Human Hypertension (2008) 22, 441–443 & 2008 Nature Publishing Group All rights reserved 0950-9240/08 $30.00 www.nature.com/jhh
COMMENTARY
Hypertension in the Asia-Pacific region C-E Chiang1,3 and C-H Chen2,3,4,5 1
Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan; 2Department of Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan; 3Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan; 4Department of Public Health, National Yang-Ming University, Taipei, Taiwan and 5I-Lan University Hospital, National Yang-Ming University, Taipei, Taiwan
Journal of Human Hypertension (2008) 22, 441–443; doi:10.1038/jhh.2008.17; published online 13 March 2008
Hypertension is a major health burden and the leading cause of death in the world.1 Although hypertension is more common in economically developed countries than in economically developing ones, it is a greater population burden in the latter because of the much larger population.2 Similarly, in the Asia-Pacific region, hypertension is particularly important as this region contains at least 65% of the world’s population.3,4 In the western pacific and south-eastern Asia regions, the prevalence of hypertension ranges from 5 to 47% in men and from 7 to 38% in women, which is comparable with that in western/developed countries.3 Although the age-standardized rate of hypertension in Korea, Thailand and Taiwan is the lowest among the seven world regions defined by the World Bank,2 the incidence of hypertension is actually high,5 due to increasing obesity and metabolic syndrome.6–8 Thus, the projected 29.2% global prevalence rate of hypertension by 2025 may be an underestimate.2 The Asia Pacific Cohort Studies Collaboration clearly demonstrated the log-linear relationships of blood pressure with ischaemic stroke, haemorrhagic stroke, ischaemic heart disease and total cardiovascular death that continue down to at least 115/75 mm Hg.9 The strong associations are very similar for both men and women, and for both Asian and Australasian cohorts but the proportional association attenuates with age.9 In Asian regions, the association between blood pressure and stroke is particularly steep, when compared to Australasia. A 10 mm Hg lower systolic blood pressure is associated with 41% lower stroke risk in Asia and 30% lower stroke risk in Australasia.9 The contribution of hypertension to cardiovascular disease has also been quantified for countries in the Asia-Pacific region.3 In this region, up to 66% of haemorrhagic stroke, 45% of ischaemic stroke and 39% of Correspondence: Professor C-H Chen, Faculty of Medicine, Division of Cardiology, National Yang-Ming University, No. 201, Sec. 2, Shih-Pai Road, Taipei Veterans General Hospital, Taipei, Taiwan. E-mail:
[email protected]
ischaemic heart disease can be attributed to hypertension.3 The major determinants of cardiovascular disease in the Asia-Pacific region are similar to those described elsewhere and include hypertension, cholesterol, diabetes and smoking.10 The association of total cholesterol with coronary heart disease and stroke is similar in Asian and Australasian cohorts. Overall, the risk of coronary death increases by 35% and fatal or non-fatal ischaemic stroke by 25%, with each 1 mmol l 1 higher level of total cholesterol.11 In addition, the joint effects of blood pressure and serum cholesterol on cardiovascular disease in the Asia-Pacific region have been investigated.11 The hazard ratios for total ischaemic stroke and ischaemic heart disease increase substantially with increasing levels of both systolic blood pressure and cholesterol, but the associations of systolic blood pressure with ischaemic heart disease and stroke risk are slightly steeper in those with low cholesterol levels.11 Cholesterol levels are not associated with the risk of haemorrhagic stroke and do not modify the association between systolic blood pressure and haemorrhagic stroke.11 In the Asia-Pacific region, diabetes is associated with a twofold increase in the risk of death from cardiovascular disease.12 For all cardiovascular outcomes, including fatal ischaemic heart disease, fatal cerebral vascular disease, nonfatal myocardial infarction and nonfatal cerebral vascular disease, hazard ratios are similar in Asian and Australasian populations and in men and women, but are greater in younger than older individuals.12 All cardiovascular associations were maintained after adjustment for systolic blood pressure, cholesterol, obesity and smoking. The interaction between hypertension and diabetes has also been investigated.13 Systolic blood pressure is associated with fatal and non-fatal cardiovascular outcomes among individuals with and without diabetes.10 Analogous to the joint effects of systolic blood pressure and cholesterol, the hazard ratio for each 10 mm Hg increment of systolic blood pressure is smaller in individuals with diabetes than in those without diabetes.10 Therefore, the results of the Asia Pacific Cohort
Hypertension in the Asia-Pacific region C-E Chiang and C-H Chen 442
Studies Collaboration do not support that systolic blood pressure is a more important determinant of cardiovascular risk among people with diabetes.10 The risk of cardiovascular disease results from the integration of multiple risk factors.14 Prevalence of cardiovascular risk factors vary among countries and regions, but the relationship of risk factors to cardiovascular morbidity and mortality appears essentially the same across Asia-Pacific and western countries.15 In the INTERHEART study enroling 15 152 cases of acute myocardial infarction and 14 820 controls from 52 countries, the risk of myocardial infarction can be accounted for by modifiable risk factors, including blood pressure, worldwide in both sexes and at all ages in all regions.16 This finding supports that preventive approaches can be based on similar principles worldwide and that cardiovascular risk can be predicted by risk models constructed from relevant prevalence of risk factors and incidence of cardiovascular outcomes.14 The fact that blood pressure is an essential component in all risk models indicates the importance of contribution of blood pressure with other risk factors in the pathogenesis of cardiovascular disease.14 Cardiovascular risk factors interact with each other. Although it is predictable that hypertensive individuals with additional cardiovascular risk factors should have greater cardiovascular risk than those with hypertension alone, few studies have quantified the risk increments. The quantified population-attributable fraction values of hypertension for cardiovascular mortality do not allow for the estimation of possible synergistic effects from other risk factors.3 In the current issue of the Journal of Human Hypertension, Lee et al.17 provides a report from the Singapore Cardiovascular Cohort Study showing that hypertensive individuals with increasing number of cardiovascular risk factors, including elevated total cholesterol/high-density lipoprotein cholesterol, smoking, diabetes mellitus and history of cardiovascular disease have increasing risk of total and cardiovascular mortality.17 Specifically, the hazards ratio was 3.7 (1.3–10.5) in the presence of any two cardiovascular risk factors and 6.0 (2.1–17.5) in the presence of any three or more cardiovascular risk factors, with reference to hypertensive subjects without any cardiovascular risk factors. The data may be useful clinically to strengthen the multiple risk factor approach for management of subjects with hypertension, in an Asian population. The study also supports that the effect of hypertension in combination with other cardiovascular risk factors on mortality outcomes in the Asian populations was broadly similar to those in the western populations. Hypertension is strongly associated with the large and growing burden of cardiovascular disease in the Asia-Pacific region.3,10 Successful reductions in blood pressure can reduce cardiovascular mortality.13 In Asian populations, the substantial potential benefits Journal of Human Hypertension
from population-wide blood pressure lowering have been clearly demonstrated.9,15 Since absolute cardiovascular risk is determined by the integrated effect of all cardiovascular risk factors, effective control of hypertension should adopt a multifactorial approach and it is essential for clinicians to screen for and manage additional cardiovascular risk factors in hypertensive patients in Asia.14,18
References 1 Ezzati M, Lopez AD, Rodgers A, Vander HS, Murray CJ. Selected major risk factors and global and regional burden of disease. Lancet 2002; 360: 1347–1360. 2 Kearney PM, Whelton M, Reynolds K, Muntner P, Whelton PK, He J. Global burden of hypertension: analysis of worldwide data. Lancet 2005; 365: 217–223. 3 Martiniuk AL, Lee CM, Lawes CM, Ueshima H, Suh I, Lam TH et al. Hypertension: its prevalence and population-attributable fraction for mortality from cardiovascular disease in the Asia-Pacific region. J Hypertens 2007; 25: 73–79. 4 Harrison W, Marshall T. The epidemiology of blood pressure in East Asia. J Hum Hypertens 2006; 20(2): 97–99. 5 Chien KL, Hsu HC, Sung FC, Su TC, Chen MF, Lee YT. Incidence of hypertension and risk of cardiovascular events among ethnic Chinese: report from a community-based cohort study in Taiwan. J Hypertens 2007; 25: 1355–1361. 6 Chuang SY, Chou P, Hsu PF, Cheng HM, Tsai ST, Lin IF et al. Presence and progression of abdominal obesity are predictors of future high blood pressure and hypertension. Am J Hypertens 2006; 19: 788–795. 7 Tesfaye F, Nawi NG, Van Minh H, Byass P, Berhane Y, Bonita R et al. Association between body mass index and blood pressure across three populations in Africa and Asia. J Hum Hypertens 2007; 21(1): 28–37. 8 Kim JA, Kim SM, Choi YS, Yoon D, Lee JS, Park HS et al. The prevalence and risk factors associated with isolated untreated systolic hypertension in Korea: the Korean National Health and Nutrition Survey 2001. J Hum Hypertens 2007; 21(2): 107–113. 9 Lawes CM, Rodgers A, Bennett DA, Parag V, Suh I, Ueshima H et al. Blood pressure and cardiovascular disease in the Asia Pacific region. J Hypertens 2003; 21: 707–716. 10 Kengne AP, Patel A, Barzi F, Jamrozik K, Lam TH, Ueshima H et al. Systolic blood pressure, diabetes and the risk of cardiovascular diseases in the Asia-Pacific region. J Hypertens 2007; 25: 1205–1213. 11 Zhang X, Patel A, Horibe H, Wu Z, Barzi F, Rodgers A et al. Cholesterol, coronary heart disease, and stroke in the Asia Pacific region. Int J Epidemiol 2003; 32: 563–572. 12 Woodward M, Zhang X, Barzi F, Pan W, Ueshima H, Rodgers A et al. The effects of diabetes on the risks of major cardiovascular diseases and death in the AsiaPacific region. Diabetes Care 2003; 26: 360–366. 13 Singh RB, Suh IL, Singh VP, Chaithiraphan S, Laothavorn P, Sy RG et al. Hypertension and stroke in Asia: prevalence, control and strategies in developing countries for prevention. J Hum Hypertens 2000; 14: 749–763.
Hypertension in the Asia-Pacific region C-E Chiang and C-H Chen 443
14 Wu Y, Liu X, Li X, Li Y, Zhao L, Chen Z et al. Estimation of 10-year risk of fatal and nonfatal ischemic cardiovascular diseases in Chinese adults. Circulation 2006; 114: 2217–2225. 15 Lida M, Ueda K, Okayama A, Kodama K, Sawai K, Shibata S et al. Impact of elevated blood pressure on mortality from all causes, cardiovascular diseases, heart disease and stroke among Japanese: 14 year follow-up of randomly selected population from Japanese— Nippon data 80. J Hum Hypertens 2003; 17: 851–857. 16 Yusuf S, Hawken S, Ounpuu S, Dans T, Avezum A, Lanas F et al., INTERHEART Study Investigators.
Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case–control study. Lancet 2004; 364(9438): 937–952. 17 Lee J, Ma S, Heng D, Chew SK, Hughes K, Tai ES. Hypertension, concurrent cardiovascular risk factors and mortality: The Singapore Cardiovascular Cohort Study. J Hum Hypertens 2008; 22: 468–474. 18 Jackson R, Lawes CM, Bennett DA, Milne RJ, Rodgers A. Treatment with drugs to lower blood pressure and blood cholesterol based on an individual’s absolute cardiovascular risk. Lancet 2005; 365: 434–441.
Journal of Human Hypertension
