Commentary: Cardiovascular implications of the epidemiological transition for the developing world: Thailand as a case in point

Daniel G Hackam and Sonia S Anand

Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada L8L 2X2.

Correspondence:
Dr Sonia S Anand, Population Health Research Institute, Department of Medicine, Room 3X28a, Health Sciences Centre, McMaster University, Hamilton, Ontario, Canada L8L 2X2. E-mail:
anands{at}mcmaster.ca

Cardiovascular disease (CVD) is currently the leading cause of death and disability in developed nations, and is increasing rapidly in the developing world.1 If demographic trends continue, it is estimated that 90% of the global CVD burden will occur in low and middle-income countries by the year 2025. The rapid increase in CVD rates in developing regions is occurring at a time when infectious and nutritional deficiency diseases are in decline, a phenomenon that has been termed ‘the epidemiologic transition’.2 East Asia, in particular, is expected to suffer some of the largest increases in CVD morbidity and mortality in coming years.

The reasons for the epidemiological transition are several-fold. As developing countries undergo economic and social transformation, prevalent diseases shift from those common to the most impoverished societies—namely infectious and nutritional diseases—to more chronic, degenerative conditions, such as cancer, atherosclerosis, and diabetes. The dramatic increase in CVD rates in developing regions also reflects substantial increases in life expectancy in many low-income societies, coupled with the greater vulnerability of middle-aged and elderly individuals to the development of CVD. With urbanization and industrialization, the population burden of vascular risk factors—hypertension, hypercholesterolaemia, diabetes, and obesity, especially—also increases. This results from the uptake of unhealthy dietary patterns which are aggressively marketed to them by the commercial food industry, and sedentary lifestyles due to the increased use of energy-saving devices (e.g. cars).

The cohort study by Sritara et al.3 is a welcome addition to the cardiovascular epidemiology literature of developing nations, a subject that until recently has attracted little attention in the West. The authors enrolled 3499 employees of the Electrical Generating Authority of Thailand, characterized their baseline risk factor profile, and followed them for 12 years (1985–1997) for the development of cardiovascular outcomes. As expected, vascular death (defined as mortality due to coronary heart disease, stroke, or other vascular causes) was the most frequent mode of death, accounting for 29.5% of causes. Increasing age, systolic and diastolic blood pressure, smoking, diabetes, obesity, and low levels of high-density lipoprotein cholesterol were all positively associated with vascular mortality, confirming the importance of these conventional risk factors in a Southeast Asian population.

Perhaps one of the most important findings of this study is that nearly all risk factors worsened substantially over the 12-year follow-up, an effect which could not be ascribed solely to ageing of the cohort. Incidence rates of hypertension, hypercholesterolaemia, diabetes, overweight/obesity, and other risk factors increased two- to three-fold. This increase in risk factor incidence helps to explain why vascular mortality tripled in Thailand during this time. On a positive note, rates of smoking amongst the employees decreased by approximately one-half over the 12-year period.

A limitation of the generalizability of the study is that it surveyed only middle class, well-educated, urban individuals, and thus may not be reflective of trends occurring in rural or impoverished areas of Thailand. However, other studies of populations in agricultural areas and slums in Thailand and nearby countries find similar, if not greater, rates of risk factors and cardiovascular mortality.4–8 For instance, Bunnag et al. found high rates of overweight (25.5%), obesity (10%), hypertension (17.3%), hypercholesterolaemia (14.1%), and hypertriglyceridaemia (24.8%), among residents dwelling in a Bangkok slum.5 Furthermore, a large nationwide survey of neighbouring Singapore conducted in 1992 similarly reported high rates of diabetes (8.4%), impaired glucose tolerance (16.1%), cigarette smoking (19.0%), and hypercholesterolaemia (47.9%).8

An important next step will be the translation of studies like Sritara’s into new population- and community-based initiatives directed at stemming the increasing burden of cardiovascular morbidity and mortality in the developing world. An excellent example of one such strategy is the National Healthy Lifestyle Programme, which was instituted in Singapore in 1992 in an attempt to reduce cardiovascular incidence rates that were among the highest in Asia.9 In the decade following initiation, there was a 39.1% decline in mortality attributable to coronary causes, and a 20.8% decline in myocardial infarction in the population. This strategy was accompanied by favourable trends in the rates of physical activity, smoking, obesity, and diabetes.10 More widespread implementation of similar interventions will require fundamental policy changes with commitment from all levels of government toward promoting healthy lifestyles, restrictions on the marketing of fast foods and soda pop, and widespread efforts to facilitate increases in daily physical activity. Only through such measures will the impending global epidemic of obesity, diabetes, and cardiovascular disease in developing nations be reversed.


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 References
 
1 World Health Organization. The World Health Report 2002. Available at: http://www.who.int/whr/2002/. Accessability confirmed 16 February 2003.

2 Yusuf S, Reddy S, Ounpuu S, Anand S. Global burden of cardiovascular diseases: part I: general considerations, the epidemiologic transition, risk factors, and impact of urbanization. Circulation2001;104:2746–53.[Abstract/Free Full Text]

3 Sritara P, Cheepudomwit S, Chapman N et al. Twelve-year changes in vascular risk factors and their associations with mortality in a cohort of 3499 Thais: The Electricity Generating Authority of Thailand Study. Int J Epidemiol 2003;32:461–68.[CrossRef][ISI][Medline]

4 Boedhi-Darmojo R. The pattern of cardiovascular disease in Indonesia. World Health Stat Q 1993;46:119–24.[Medline]

5 Bunnag SC, Sitthi-Amorn C, Chandraprasert S. The prevalence of obesity, risk factors and associated diseases in Klong Toey slum and Klong Toey government apartment houses. Diabetes Res Clin Pract 1990;(10 Suppl.1):S81–S87.[CrossRef][ISI][Medline]

6 Ismail MN, Chee SS, Nawawi H, Yusoff K, Lim TO, James WP. Obesity in Malaysia. Obes Rev 2002;3:203–08.[CrossRef][Medline]

7 Sitthi-Amorn C, Chandraprasert S, Bunnag SC, Plengvidhya CS. The prevalence and risk factors of hypertension in Klong Toey slum and Klong Toey government apartment houses. Int J Epidemiol 1989; 18:89–94.[Abstract]

8 Tan CE, Emmanuel SC, Tan BY, Jacob E. Prevalence of diabetes and ethnic differences in cardiovascular risk factors. The 1992 Singapore National Health Survey. Diabetes Care 1999;22:241–47.[Abstract]

9 Tan AT, Emmanuel SC, Tan BY, Teo WS, Chua TS, Tan BH. Myocardial infarction in Singapore: a nationwide 10-year study of multiethnic differences in incidence and mortality. Ann Acad Med Singapore 2002;31:479–86.[ISI][Medline]

10 Cutter J, Tan BY, Chew SK. Levels of cardiovascular disease risk factors in Singapore following a national intervention programme. Bull World Health Organ 2001;79:908–15.[ISI][Medline]





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