Health Transition And Emerging

Cardiovascular Diseases In Developing

Countries

Dr Sunita DodaniDepartment of Epidemiology

University of Pittsburgh

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

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)

0

10

20

30

40

50

60

70

80

1950 1960 1970 1980 1990

(Age

in y

ears

) World

LessDeveloped

MoreDeveloped

Rising Life Expectancy

WHO report, 1997

Epidemiologic TransitionPast, 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)

Epidemiologic Transition

Demographic transitions: Indicators over time

(UK as an indicator for the ‘western’ Model)

0

10

20

30

40

50

1800 1840 1880 1920 1960

population(Millions)

Birt

h &

Dea

th R

ate

(per

100

0) PopulationDeath RateBirth Rate

Mortality Rate

Fertility Rate

Birth Rate

Size Population

Age Population

Omran, Millbank Mem Fund Quart, 1971;49,215

Epidemiologic Transition

Models of Demographic transitions

05

101520253035404550

1800 1840 1880 1920 1960

05

101520253035404550

1800 1840 1880 1920 19600

510

15

2025

30

35

4045

50

1800 1840 1880 1920 1960

Western

Accelerated Delayed (Most LDC)

UK Japan Sri Lanka

Omran, Millbank Mem Fund Quart, 1971;49,215

18001840

1880

1920

1960 1800

1840

1880

1920

1960 18001840

18801920

1960

Epidemiologic TransitionRecent declines in Fertility rates in developing countries

(United Nations 1993)

1965-70 1985-90 Prop. Diff

Thailand 6.1 2.3 62%

China 6.0 2.3 62%

Bangladesh 6.9 3.6 48%

Turkey 5.6 3.0 46%

Mexico 6.7 3.8 43%

Indonesia 5.6 3.3 41%

Brazil 5.3 3.5 34%

Egypt 6.6 4.4 33%

India 5.7 4.2 26%

Philippines 6.0 4.7 21%

Pakistan 7.0 7.0 0%

Nigeria 6.9 6.9 0%

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)

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)

Epidemiologic transition

Current & Projected Burden of Diseases

0%10%20%30%40%50%60%70%80%90%

100%

1990 2020 1990 2020 1990 2020

Perc

ent o

f tot

al b

urde

n

Injuries

Non Communicable disease

Communicable disease

China India Rest of Asia

(Murray & Lopez, 1990)

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.

Epidemiologic Transition

Low income

high income plus middle income

World countries countries

Total death

Thousands 53,929 8,033 45,897

Percentage 14.9 85.1

Non communicable disease (NCDs)

Thousands 31,717 7,024 24,693

Percentage 22.1 77.9

Total disability-adjusted life years (DALYs) lost

Thousands 1,382,564 108,305 1,274, 259

Percentage 7.8 92.2

DALY loss due to NCDs

Thousands 595,363 87,732 507,631

Percentage 14.7 85.3

Global burden of disease(1998): Contribution of low and middle income countries

Epidemiologic transitionDeterminants and dynamics of the CVD

Epidemic in the developing Countries

Health transitions: demographic transitions and epidemiologic transitions

Industrialization and Urbanization

Economic Social & Environmental Changes

Public sanitation

Housing health care

Nutrition technology for health care

Mortality

Infant

Mortality

Life expectancy

fertilityPer capita Income

Wealth

Level of RF: fat, calories, tobacco, sedentary habits

NCD

Infectious diseases

Persons at risk of developing NCDs

Increasing and aging Population

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”

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)

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.

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

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

Burden of CVD in PakistanPopulation 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

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 25- 44 years.- In females, 37% in 24-44 years and 40% in 45-64 years in urban female population

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

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.