1. Dr Sunita Dodani Department of Epidemiology University of Pittsburgh
Health Transition And Emerging Cardiovascular Diseases In Developing Countries
Dr Sunita Dodani
Department of Epidemiology
University of Pittsburgh

2. Presentation overview
By the end of this lecture we will learn about
Epidemiologic & demographic transition in developing countries
Examples of demographic transition
Double burden of diseases
Causes of Epidemiologic transition
Available CVD data in Pakistan
What can be done to reduce the burden

3. Epidemiologic Transition
A characteristic shift in the disease pattern of a population as mortality falls during the demographic transition: acute, infectious diseases are reduced, while chronic, degenerative diseases increase in prominence, causing a gradual shift in the age pattern of mortality from younger to older ages
(Omran 1970s)
The classic definition of Health transition or epidemiologic transition is “A characteristic shift in the disease
pattern of a population as mortality falls during the demographic transition: acute, infectious diseases are reduced, while chronic, degenerative diseases increase in prominence, causing a gradual shift in the age pattern of mortality from younger to older ages. In general, Epidemiologic transitions
(in general), Any major shift in patterns of disease or causes of death that affects the level and character of mortality in a population.

4. Rising Life Expectancy
Life expectancy has risen from below to almost 70 years during the industrial era. Three major factors have contributed to this
increase
Improved living standards
public health &
medical care
All are important, though to varying degrees in different eras.
WHO report, 1997

5. Epidemiologic Transition Past, Present & Future
Historical ETs
rise of infectious disease (~8000 B.C)
decline of infectious disease & rise of CVD (19th-20th C)
decline of cardiovascular disease (late 20th C)
Reverse ETs
rise of violence (late 20th C)
resurgent infectious disease (late 20th C)
Possible future ETs
decline of cancer, dementia, etc. (21st C ?)
(WHO,2000)
Mortality decline will probably continue, but what this means for quality of life and social dependency is uncertain

6. Epidemiologic Transition
Demographic transitions: Indicators over time
(UK as an indicator for the ‘western’ Model)
Mortality Rate
Fertility Rate
Birth Rate
Size Population
Age Population
Why should one practice prevention?
The world is healthier than it has ever been, with a 30 year global increase in the past 100 years. The dramatic increase in life expectancy that was observed in the past century in both developing and developed world can be attributed primarily to improved preventive practices, not to advances in clinical medicine. It has been estimated that the majority of the increase in life expectancy was due to prevention.
Omran, Millbank Mem Fund Quart, 1971;49,215

7. Epidemiologic Transition
Models of Demographic transitions
Western
Accelerated
Delayed (Most LDC)
Mortality and birth rate driven to various extents of socio-economic development, public health and medical interventions
Sri Lanka UK
Japan
1800
1880
1960
1800
1880
1960
1800
1880
1960
1840
1920
1840
1920
1840
1920
Omran, Millbank Mem Fund Quart, 1971;49,215

8. Epidemiologic Transition
Recent declines in Fertility rates in developing countries
(United Nations 1993)
Prop. Diff
Thailand %
China %
Bangladesh %
Turkey %
Mexico %
Indonesia %
Brazil %
Egypt %
India %
Philippines %
Pakistan %
Nigeria %

9. Epidemiologic Transition
Epidemics of NCDs are presently emerging, or accelerating, in most developing countries
CVDs, cancers, diabetes, neuropsychiatric ailments and other chronic diseases are major contributors to the burden of disease
Infections and nutritional deficiencies are receding as leading contributors to death and disability….. Still prevalent
Double Burden of Diseases (Murray & Lopez, 1996)
The second half of the 20th century witnessed major health transitions in the world, propelled by socio-economic and technological changes that profoundly altered life expectancy and ways of living, while creating an unprecedented human capacity to use science to prolong and enhance life. The most globally pervasive change among these health transitions has been the rising burden of non-communicable diseases (NCDs). Epidemics of NCDs are presently emerging, or accelerating, in most developing countries1. Cardiovascular diseases (CVDs), cancers, diabetes, neuropsychiatric ailments and other chronic diseases are becoming major contributors to the burden of disease, even as infections and nutritional deficiencies are receding as leading contributors to death and disability

10. Cardiovascular disease transition
What is current burden of diseases in Asia?
Asia has 50% percent of the total world's burden of disease.
countries vary on where they are on the economic development and epidemiologic transition spectrum.
Leaving China aside, India and the rest of Asia--a heterogeneous group of 49 countries-- about 50% of this burden is from communicable diseases (such as diarrhea)
Another 40%from noncommunicable diseases
10 percent is from other causes, such as injuries (Murray & Lopez, 1990)
Asia has 50 percent of the total world's burden of disease, countries vary on where they are on the economic development and epidemiologic transition spectrum. For example, Bangladesh and Nepal are at one end of the spectrum, while Taiwan and Singapore are at the other.
Leaving China aside for the moment because of its size, when we look at India and the rest of Asia--a heterogeneous group of 49 countries--we see that about 50 percent of this burden is from communicable diseases (such as diarrhea) that could be prevented or reduced with better education and improvements in the household environment or through simple treatments, like oral rehydration therapy. Another 40 percent is from noncommunicable diseases, such as cancer, cerebrovascular disease, and ischemic heart disease, that could be mitigated by decreases in tobacco use and changes in diet, while the final 10 percent is from other causes, such as injuries.

11. Epidemiologic transition
Current & Projected Burden of Diseases
China
India
Rest of Asia
Why should one practice prevention?
The world is healthier than it has ever been, with a 30 year global increase in the past 100 years. The dramatic increase in life expectancy that was observed in the past century in both developing and developed world can be attributed primarily to improved preventive practices, not to advances in clinical medicine. It has been estimated that the majority of the increase in life expectancy was due to prevention.
(Murray & Lopez, 1990)

12. Epidemiologic transition
Asia is evenly burdened by both the unfinished agenda of communicable diseases and the growing burden of noncommunicable diseases.
This is different from what we see in the established market economies, driven by noncommunicable diseases, and in sub-Saharan Africa, driven by communicable diseases.
While the information must be viewed cautiously because of the set of assumptions needed to perform a 30-year projection, the data reveal an important message: In Asia, the burden of communicable disease is expected to be cut by half. By 2020, between 55 and 80 percent of the total burden of disease will be attributable to noncommunicable diseases.

13. Epidemiologic Transition
Global burden of disease(1998): Contribution of low and middle income countries
Low income
high income plus middle income
World countries countries
Total death
Thousands , , ,897
Percentage
Non communicable disease (NCDs)
Thousands , , ,693
Percentage
Total disability-adjusted life years (DALYs) lost
Thousands ,382, , ,274, 259
Percentage
DALY loss due to NCDs
Thousands , , ,631
Percentage
This is reflected in the current high burdens, as well as the estimated escalation of those burdens over the next two decades. The current high burden of NCDs is highlighted by the estimates for that indicate these disorders contributed to 58.8% of global mortality and 43% of the global burden of disease, measured as disability-adjusted life years (DALYs) lost. The contribution of low- and middle-income countries to this burden is large; about 77% of the total mortality and 85% of the total burden of disease attributable to NCDs arises from these countries (Table 1). Even within these regions, which are experiencing a double burden of pre-transitional and post-transitional diseases, NCDs contributed to 53.8% of total mortality and 39.8% of the total disease burden. Globally, the mortality attributable to NCDs from 1990 to 2020 is expected to rise from 55.5% to 72.6%, and NCD-related DALY loss from 34.7% to 59.8%
Ref: 1.World Health Organization (WHO). The World Health Report. Geneva: WHO, 1999
2. Murray CJL, Lopez AD. Global Comparative Assessments in the Health Sector. Geneva: World Health Organization, 1994

14. Epidemiologic transition
Determinants and dynamics of the CVD Epidemic in the developing Countries
Health transitions: demographic transitions and epidemiologic transitions
Mortality
Infant
Life expectancy
fertility
Industrialization and Urbanization
Public sanitation Housing health care
Nutrition technology for health care
Economic Social & Environmental Changes
Per capita Income
Wealth
There are several factors that explain the recent emergence, and underlie the projected escalation, of the CVD epidemic in the developing countries. First, a global surge in life expectancy, especially in the developing countries. Many more individuals are exposed to risk factors of CVD for sufficient duration, for clinical consequences to manifest as a greater proportion of the population survives into older decades. This epidemiological transition – due to changing demographic profiles and a decline in the competing causes of death from infectious and nutritional disorders – characterizes the advent of the CVD epidemic, along with those of other chronic diseases. This has been clearly demonstrated in urban China, where mortality attributable to CVD increased from 86.2 per 100 000 (12.1% of total deaths) in 1957 to per 100 000 (35.8% of all deaths) in Similar projections of a demographic transition, and an accompanying rise in CVD burdens, exist for India as well.
Second, delayed industrialization and recent urbanization have been associated with alteration in living habits, with deleterious changes in diet, physical activity and tobacco addiction. These environmental changes lead to acquisition or accretion of risk factors. The increased ‘dose’ of risk factor exposure, coupled to longer duration of exposure due to demographic changes, leads to an enhanced risk of CVD. In China, the Sino-MONICA study demonstrated that the body mass index (BMI), hypertension and blood cholesterol levels in the population, age group 35–64 years, rose from 1984–86 to 1988–89.
refYao C, Wu W, Wu Y. The changing pattern of cardiovascular disease in China. World Health Stat. Quart. 1993; 46: 113– Bulatao RA, Stephens PW.Global Estimates and Projections of Mortality by Cause. Preworking Paper Washington, DC: Population Health and Nutrition Department, World Bank, 1992
Persons at risk of developing NCDs
NCD
Infectious diseases
Increasing and aging Population
Level of RF: fat, calories, tobacco, sedentary habits

15. Determinants and dynamics of the CVD Epidemic in the developing Countries
Data from South Asian Immigrant studies
Excess, early, and extensive CHD in persons of South Asian origin
The excess mortality has not been fully explained by the major conventional risk factors.
Diabetes mellitus and impaired glucose tolerance highly prevalent. (Reddy KS, circ 1998).
Central obesity, ↑triglycerides, ↓HDL with or without glucose intolerance, characterize a phenotype.
genetic factors predispose to ↑lipoprotein(a) levels, the central obesity/glucose intolerance/dyslipidemia complex collectively labeled as the “metabolic syndrome”
Several studies around the world have consistently revealed excess, early, and extensive CHD in persons of South Asian origin. The excess mortality has not been fully explained by the major conventional risk factors in cross-sectional comparisons with other population groups. Diabetes mellitus and impaired glucose tolerance are, however, highly prevalent in South Asian migrants. Central obesity, high levels of triglycerides, and low levels of HDL cholesterol, with or without glucose intolerance, seem to characterize a phenotype frequently noted among South Asian migrants.
Thus, South Asians in urban and migrant environments may be at a higher risk of CHD due to the confluence of (1) genetic factors that predispose to higher lipoprotein(a) levels, the central obesity/glucose intolerance/dyslipidemia complex collectively labeled as the "metabolic syndrome," and a possible "thrifty gene" effect with (2) environmental influences that lead to weight gain, rise in plasma cholesterol and blood pressure levels, and, as yet inadequately studied, probable psychosocial risk factors.

16. Determinants and dynamics of the CVD epidemic in the developing countries
Other Possible factors
Relationship between early life characteristics and susceptibility to NCD in adult hood ( Barker’s hypothesis) (Baker DJP,BMJ,1993)
Low birth weight associated with increased CVD
Poor infant growth and CVD relation
Genetic–environment interactions
(Enas EA, Clin. Cardiol. 1995; 18: 131–5)
Amplification of expression of risk to some environmental changes esp. South Asian population)
Thrifty gene (e.g. in South Asians)
There are also possible adverse effects of poor childhood nutrition14 that, if conclusively proven, would have an enormous impact on the developing countries, which still have a substantial fraction of the population that was underweight at birth.
Ref: Barker DJP, Martyn CN, Osmond C, et al. Growth in utero and serum cholesterol concentrations in adult life. Br. Med J. 1993; 307: 1524–7
The possibility of such programming, or as yet unascertained genetic factors, may underlie the enhanced susceptibility of some ethnic groups (e.g. South Asian migrants) to CHD15. This excess risk may be explained by gene–environment interactions or fetal programming in these groups, but public health action must focus on the environmental changes that trigger the expression of susceptibility
Ref: Enas EA, Mehta J. Malignant coronary artery disease in young Asian Indians. Thoughts on pathogenesis, prevention and therapy. Clin. Cardiol. 1995; 18: 131–5.
Such genetic environmental interactions may need to be clarified in the varied ethnocultural populations of the developing countries so that the relevant environmental interventions could be preferentially promoted for CVD prevention.

17. CVD epidemic in developing & developed countries. Are they same?
The determinants of health transition in the developing countries are similar to those that charted the course of the epidemics in the developed countries but dynamics are different.
The compressed time frame of transition in the developing countries imposes a large, double burden of communicable and non-communicable diseases.
Urbanization in developing countries occurs in settings of high poverty levels and international debt, restricting resources for public health responses.
Prevention began in developed countries when the epidemic had peaked, and often accelerated a secular downswing, while the efforts in the developing countries are commencing when the epidemic is on the upswing.
While the determinants of health transition in the developing countries are similar to those that charted the course of the epidemics in the developed countries, their dynamics are different.
The epidemiologic transition in Asia is very different from the classic transition that occurred in the West. First, the transition in the West was essentially reciprocal--communicable diseases went down and were replaced by a rising burden of noncommunicable diseases. In the developing countries of Asia, however, there is an overlap, with countries having to face fairly significant burdens of communicable and noncommunicable disease simultaneously.
Second, the transition is occurring much faster in Asia's developing countries than it did for countries in the industrialized West. One reason may be the rapid economic growth and improvements in health care infrastructure that have paralleled the shift in the causes of ill-health.
The compressed time frame of transition in the developing countries imposes a large, double burden of communicable and non-communicable diseases. Unlike in the developed countries where urbanization occurred in prospering economies, urbanization in developing countries occurs in settings of high poverty levels and international debt, restricting resources for public health responses. Organized efforts at prevention began in developed countries when the epidemic had peaked, and often accelerated a secular downswing, while the efforts in the developing countries are commencing when the epidemic is on the upswing. Strategies to control CVD in the developing countries must be based on recognition of these similarities and differences. Principles of prevention must be based on the evidence gathered in developed countries, but interventions must be context-specific and resource-sensitive

18. CVD epidemic in developing & developed countries. Are they same?
Urban populations have higher levels of CVD risk factors related to diet and physical activity (overweight, hypertension, dyslipidaemia and diabetes)
Tobacco consumption is more widely prevalent in rural population
The social gradient will reverse as the epidemics mature.
The poor will become progressively vulnerable to the ravages of these diseases and will have little access to the expensive and technology-curative care.
The scarce societal resources to the treatment of these disorders dangerously depletes the resources available for the ‘unfinished agenda’ of infectious and nutritional disorders that almost exclusively afflict the poor
At present, urban populations in most developing countries have higher levels of cardiovascular risk factors that are related to diet and physical activity (overweight, hypertension, dyslipidaemia and diabetes), while tobacco consumption is more widely prevalent in rural populations27,28. This suggests that tobacco consumption is influenced more by education and is the earliest risk factor to demonstrate a reversal of the social gradient. The other risk factors are influenced by more complex social interactions affecting diet and exercise and their social gradients reverse relatively slowly.
The economic and social consequences of the CVD epidemics in the developing countries will be devastating. The social gradient will reverse as the epidemics mature, as has happened in other nations that have experienced their fury in full form. Even at present, several of the risk factors of chronic diseases are showing a reversal of the social gradient in many developing countries4. The poor will become progressively vulnerable to the ravages of these diseases and will have little access to the expensive and technology-intensive management that clinical care demands. Also, the diversion of scarce societal resources to the treatment of these disorders dangerously depletes the resources available for the ‘unfinished agenda’ of infectious and nutritional disorders that almost exclusively afflict the poor

19. Burden of CVD in Pakistan
Coronary heart disease
Mortality statistics
Specific mortality data ideal for making comparisons with other countries are not available
Inadequate and inappropriate death certification, and multiple concurrent causes of death
Limited data available due to scarce research. A paucity of cause-specific mortality data in the developing countries is a major impediment to the estimation of the absolute and relative death toll of CVD or in evaluating the time trends in mortality

20. Burden of CVD in Pakistan
Population surveys
Pitfalls in sampling design, sample size standardization and measurement errors, but still remain the most important source of information today
National health Survey of Pakistan (NHSP)
Ischemic Heart Disease (IHD) was reported as 12% of the adult mortality in Pakistan.
Tobacco use: 29% and 3.4 % in adult males and females’ respectively
Hypertension
- estimated 12 million hypertensives in the country of the total 120 million population
- Prevalence is 17.9 % of the overall adult population with 16.4% and 21.5% being the rural and urban prevalence.
- > 45 years, one in three Pakistanis (33%) are hypertensive
- 3% adequately controlled
This 4-year countrywide community survey was conducted with collaborative efforts between Pakistan Medical Research Council, Federal Bureau of Statistics of Pakistan, Department of Health and Human Services, Washington, USA and Center of Disease Control, USA (CDC). It provides a detailed picture of patterns of disease, conditions and risk factors, which affect the health of Pakistanis. According to NHSP Ischaemic Heart Disease (IHD) was reported as 12% of the adult mortality in Pakistan.
Hypertension is the most common risk factor of IHD in Pakistan and there were according to NHSP, an estimated 12 million hypertensives in the country of the total 120 million population.49
The prevalence of hypertension (blood pressure≥140\90 mmHg or on anti- hypertensive drugs) was seen in 17.9 % of the overall adult population with 16.4% and 21.5% being the rural and urban prevalence respectively. Above the age of 45 years, one in three Pakistanis (33%) was hypertensive and overall, only 3% of the hypertensives were adequately controlled. Furthermore 85% of hypertensives in rural areas were unaware of their hypertension

21. Burden of CVD in Pakistan
Diabetes
- Pakistan is among the top 10 world nations for high numbers of people with diabetes
- Prevalence… 10.6%
Obesity (WHO criteria)
- 1 in 7urban males adults (>15 years) is obese or overweight with 22% prevalence in males of years.
- In females, 37% in years and 40% in years in urban female population
one in seven urban males adults over 15 years was obese or overweight with 22% prevalence in males of years. In comparison, obesity was more common in females, 37% in years and 40% in years in urban female population

22. Burden of CVD in Pakistan
Temporal Trends
Most of our knowledge about prevention and treatment derives from studies conducted in developed countries and predominantly among white populations
Validated nationally representative estimates of cause specific mortality and morbidity are not available for any country in South Asia
CHD mortality rate of South Asian immigrants compared with other populations remains high.
CVDs are major and growing contributors to mortality and disability in South Asia
These data indicate that the high rates of CHD with economic changes are reversible and perhaps even avoidable. Therefore, lessons learnt from migrant SAs may be helpful in developing prevention strategies for the Indian subcontinent.

23. Prevention of CVD
There is an urgent need to establish appropriate research studies, increase awareness of the CVD burden, and develop preventive strategies.
Prevention and treatment strategies that have been proven to be effective in developed countries should be adapted for developing countries.
Prevention is the best option as an approach to reduce CVD burden.
Do we know enough to prevent this CVD Epidemic in the first place.
Validated nationally representative estimates of cause specific mortality are not available for any country in South Asia
Therefore, there is an urgent need to establish appropriate research studies, increase awareness of the CVD burden, and develop preventive strategies in developing countries. In the meantime, as it is likely that most risk factors will be of some importance in all ethnic populations in the world, prevention and treatment strategies that have been proven to be effective in developed countries should be adapted for developing countriesb
Establishment of surveillance systems for noncommunicable diseases and their risk factors is essential for developing prevention strategies and monitoring the impact of control programmes. Pilot programmes are now under way in some of the countries to establish and evaluate such systems.