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Cardiovascular Epidemiology in the Americas

Andreas Wielgosz, M.D.

Introduction
Mortality
Morbidity
Risk Factors
Tobacco Use
Diet and Cholesterol
High Blood Pressure
Physical Activity
Future Needs for Surveillance of Risk Factors
Infective Causes
Interventive Care
Conclusions
References 

Introduction

The 20th century, particularly the second half, has been associated with an unprecedented expansion of the population and migration to large urban areas in both hemispheres of the Americas. In 1960, six of the world’s fifteen largest cities were in the Americas, New York being the largest in the world with 14.2 million people. Sao Paulo, with a population of less than 5 million, was not on that list. By 1994, Los Angeles had nearly doubled its population to 12.2 million, Mexico City had nearly tripled to 15.5 million and Sao Paulo was the third largest city in the world with a population of 16.1 million (Table 1). These cities continue to grow at a rate of 0.4 to 1.8 % per year. 1

Table 1. World’s Fifteen Largest Mega-Cities, Their Population and Average Annual Rate of Change in Population.

Mega-cities

Population 1994
(Millions)

Average annual rate of change in population
1990-2000 (%)

Tokyo, Japan

26.5

1.08

New York, United States of America

16.3

0.36

São Paulo, Brazil

16.1

1.82

Mexico City, Mexico

15.5

0.81

Shanghai, China

14.7

2.47

Bombay, India

14.5

3.94

Los Angeles, United States of America

12.2

1.38

Beijing, China

12.0

2.67

Calcutta, India

11.5

1.90

Seoul, Republic of Korea

11.5

1.51

Jakarta, Indonesia

11.0

4.20

Buenos Aires, Argentina

10.9

0.69

Osaka, Japan

10.6

0.11

Tianjin, China

10.4

2.90

Rio de Janeiro, Brazil

9.8

0.71

Adapted from reference 1.

At the same time life expectancy is increasing in large part due to control of infectious diseases and decreasing infant mortality. Over a 40 year span from 1950, life expectancy at birth, in the developing world of the Americas, has increased from 51 to 69 years.2 In the last ten years alone, infant mortality rates have declined from 47 per 1,000 live births to just over 30, while life expectancy at birth has increased from 68.7 to 71.1 years. 3 However, aggregate data can be misleading as there are wide variations in subregions and even within countries. For some Latin American and Caribbean countries infant mortality rates are ten times or more higher than those in Canada and the United States and overall life expectancy is 3 years shorter. Nevertheless, with increasing longevity, the age distributions of populations in the Americas are shifting away from the traditional pyramidal profile.

As infectious diseases are controlled through public health measures, non-communicable diseases emerge as leading causes of death and disability. Such a transition occurred most notably in North America after World War I with a rapid rise in mortality, particularly from ischemic heart disease, that peaked about mid century.4 In other regions of the Americas, such an epidemiologic shift was not noted until recently, in part because the transition began later and in large part because disease reporting has not been as extensive or reliable. In this presentation I examine the current epidemiologic profile of countries in the Americas, focusing on the rapidly industrializing countries of Latin America. At the same time I identify the needs to achieve a better understanding of the extent of cardiovascular diseases (CVD) and their trends over time, particularly in the context of preventing their further spread.

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Mortality

In 31 of 35 countries in the Americas, for which reported death statistics are available, CVD are the leading cause of death. The highest mortality rates in the Americas for men are currently noted in Argentina, Trinidad and Tobago, Paraguay, Brazil and Puerto Rico.5 Figure 1. For women, the highest mortality rates are reported in Brazil, Paraguay, Trinidad and Tobago, the Dominican Republic, Columbia and Argentina. Since the 1960s, there has been a notable decline in all categories of cardiovascular disease mortality. Even some of the developing countries, particularly those with higher rates, i.e. Argentina and Trinidad and Tobago, are experiencing a decline in mortality from diseases of the circulatory system, while in countries such as the Dominican Republic, El Salvador and Guatemala rates are still increasing. Table 2.

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Table 2. Percent change in age-adjusted mortality rates from cardiovascular diseases,
by country and sex , between 1968 and 1989.

country

diseases of the
circulatory system

ischemic heart disease

cerebro-vascular disease

hypertensive disease
  Men Women Men Women Men Women Men Women

Argentina

-11.9

-8.9

-49.0

-52.9

-21.4

-23.1

-45.6

-50.0

Barbados

-21.7

-21.8

5.9

30.2

-30.0

-33.7

-59.9

-57.4

Canada

-34.4

-34.6

-37.6

-37.6

-45.4

-44.2

-52.6

-52.8

Chile

-27.2

-36.3

-20.4

-30.0

-21.6

-31.4

-34.5

-34.9

Colombia

-1.1

-14.7

24.4

9.2

11.0

-0.5

-65.3

-68.9

Costa Rica

-9.3

-30.3

33.3

6.1

-16.4

-28.0

10.0

-20.0

Cuba

-16.3

-18.7

-5.7

-4.9

-26.1

-30.9

-68.1

-68.8

Dominican Republic

44.9

35.9

33.2

37.7

12.6

0.6

35.2

-35.7

El Salvador

91.7

57.8

153.1

90.0

11.9

14.3

-73.0

-44.2

Guatemala

21.4

11.0

149.5

132.4

-0.6

12.4

37.5

42.9

Mexico

-9.3

-23.9

5.0

-13.6

-24.3

-33.9

17.0

10.9

Trinidad and Tobago

-28.8

-29.1

-0.9

5.2

-34.3

-34.5

-29.3

-32.3

United States of America

-36.3

-32.6

-48.2

-45.7

-54.3

-50.3

-12.5

-14.9

Uruguay

-22.0

-21.6

-35.5

-40.8

-23.9

-18.9

-58.0

-56.1

Venezuela

-23.0

-21.2

-24.1

-25.4

-25.3

-22.6

2.8

1.0

Adapted from reference 6.

Trends for ischemic heart disease mortality are showing continuous declines in many countries including Argentina, Canada, Chile, the United States, Uruguay and Venezuela.6 On the other hand, increases are occurring particularly in Guatemala, El Salvador and the Dominican Republic. Mortality rates from cerebrovascular disease are generally declining in the Americas, with the greatest decline seen in the United States and Canada. The exceptions include El Salvador and the Dominican Republic for both sexes, Colombia for men and Guatemala for women, which are still increasing. Likewise, mortality from hypertensive disease is declining in the Americas with the exception of Guatemala, Mexico and Venezuela for both sexes, and the Dominican Republic and Costa Rica for men.

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In Latin America in 1990, about 25% of all deaths or approximately 800,000 deaths were due to CVD.5 In Canada, CVD accounted for 40.1% of all deaths which is comparable to 43.3% in the United States. Table 3. The largest proportion of deaths from CVD was noted in Argentina, Cuba, the United States, Canada and Trinidad and Tobago. In all countries of the Americas for which data are available, the proportion was greater in women than in men.

Table 3. Proportion of deaths from diseases of the circulatory system
relative to deaths from all causes, by country and sex, for 1990.

Country

total

men

women

Argentina

46.4

44.0

49.4

Belize

24.7

20.9

29.3

Brazil

34.4

30.9

39.6

Canada

40.1

38.3

42.2

Chile

29.0

25.6

33.4

Colombia

30.9

26.0

38.2

Costa Rica

28.9

26.7

31.8

Cuba

43.5

41.6

45.8

Dominican Republic

27.2

25.7

29.0

Ecuador

20.7

18.7

23.2

El Salvador

20.6

16.9

26.3

Mexico

20.3

17.5

23.9

Nicaragua

18.9

16.2

21.4

Panama

29.3

26.6

33.2

Paraguay

36.9

35.4

38.5

Peru

19.4

18.5

20.4

Puerto Rico

34.0

30.5

38.7

Suriname

33.5

32.3

35.0

Trinidad and Tobago

38.4

35.9

41.3

United States of America

43.3

40.4

46.4

Uruguay

41.4

37.5

46.0

Venezuela

29.3

26.8

32.6

Adapted from reference 5.

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Cause of death data have been collected and coded systematically according to the International Classification of Diseases, by the majority of countries in the Americas over the last 35 years.7 The extent of death registration in the Americas is comparatively high with 80% of the regional population accounted for.8 Table 4. On a worldwide comparison, this is second to the European region (94%). Among developing countries, Latin American and Caribbean countries provide the best coverage. The reliability of the data can be assessed by the proportion of deaths that are medically certified and by the proportion that are attributed to ill-defined causes. Here too, Latin American countries provide the most reliable data of all developing countries.9

Table 4. Estimated coverage of death registration in selected countries of the Americas.

Country

Year

Estimated Death Registration Coverage (%)

Argentina

1991

93

Barbados

1992

100*

Belize

1989

79

Brazil

1989

70

Canada

1993

94

Chile

1991

96

Colombia

1991

83

Costa Rica

1991

95

Cuba

1990

100*

Ecuador

1990

64

El Salvador

1991

69

Jamaica

1985

100*

Mexico

1993

87

Nicaragua

1991

39

Panama

1989

78

Paraguay

1987

82*

Peru

1989

43

Puerto Rico

1992

100*

Suriname

1992

80

Trinidad and Tobago

1991

100*

United States of America

1992

96

Uruguay

1990

98

Venezuela

1989

82

* estimated deaths may slightly exceed actual deaths in the case of islands with small populations and variable migration.
Adapted from reference 8.

However, interpretation of mortality data from the developing countries of the Americas is limited by the lack of complete coverage, the limited extent of medical certification and population mobility. With increasing immigration and migration to urban areas and the lack of data on duration of inhabitation, the geographical significance of mortality statistics becomes tenuous. Furthermore, mortality statistics alone do not offer any explanation about the observed changes in mortality patterns. The challenge for mortality surveillance in the Americas is not only to improve registration and certification but also to facilitate linkage to relevant personal data. Linking mortality outcomes to data on risk factors, psychosocial and economic characteristics, and data pertaining to health care encounters would provide a better understanding of disease processes.10

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Morbidity

Data on the prevalence of CVD are limited in all countries of the Americas but particularly in countries outside North America. There are two major sources of such data: hospital separations and surveys. In Canada and in the United States, all nonfatal (as well as fatal) hospital separations are routinely reported to provincial or state administrators and ultimately to national offices responsible for health statistics. In most Latin American and Caribbean countries such data are either not collected at all or, when available, they describe only small and select groups of patients.

In Canada, in fiscal 1991-2, CVD accounted for the greatest proportion of days of hospitalization (19%) with the length of stay in hospital for CVD exceeding the average for all causes (17.5 days vs. 11.4 days).11 In the United States, in 1994, CVD were also the leading diagnoses among all disease categories for patients discharged from hospital.12 Estimates in Latin America are available for only a few countries. An examination of live hospital discharges (1995) in select Latin American countries reveals that diseases of the circulatory system in Ecuador, accounted for only 4% or 23,944 of all discharge diagnoses in men and women combined for all hospitals in the country.13 The number of acute myocardial infarctions was 723, which was exceeded nearly 5-fold by the number of cases of cerebrovascular disease (3323). In Paraguay, 2.5% or 1555 of discharges were due to diseases of the circulatory system. The number of myocardial infarctions (52) was slightly greater than the number of cases of cerebrovascular disease (37).14 However, these data do not include private health care institutions.

Interpretation of hospital morbidity data is difficult and generalizations must be undertaken with extreme caution because the extent of reporting, reliability and validity of diagnoses vary greatly from country to country.

Physician encounters, which usually serve administrative or billing purposes, can provide estimates of the prevalence of disease with the caveat that clinical diagnoses may not be entirely reliable. Based on surveys which sampled 652 office-based physicians and specialists throughout Canada, it was estimated that in 1994 there were 264 million visits to physicians. Of these, nearly ten percent (9.9%) were for CVD. Half of those visits were for management of high blood pressure, 25% were for ischemic heart disease and 25% were for other CVD.11

The prevalence of CVD in the United States has been estimated from the National Health and Nutrition Examination Surveys (NHANES). Based on these surveys, 57.5 million Americans or over 20% of males and females have some form of CVD, with high blood pressure in 50 million, coronary disease in 13.7 million, stroke in 3.9 million and rheumatic fever/heart disease in 1.4 million.12

The burden of disease can also be examined by combining losses from premature death with loss of healthy life resulting from disability to derive disability-adjusted life years (DALYs).15 It is estimated that 1,362 millions of DALYs, or 259 DALYs/1,000 population, were lost in 1990 worldwide. Of these, 42.2% were due to non-communicable diseases, while 45.8% and 11.9% were due to communicable diseases and injuries, respectively. Table 5. In Latin America and the Caribbean, the amount of estimated DALY loss was 103 millions, or 233 DALYs/1,000 population. In established market economies, 94 millions of DALYs were lost, representing 117 DALYs/1,000 population. Non-communicable diseases are responsible for over three-fourths of DALY loss in industrialized nations, with over 15% due to CVD.

Table 5. Distribution of DALY loss by cause for selected areas, 1990.

Cause

World

(%)

Latin America and the Caribbean

(%)

Countries with Established Economies

(%)

Communicable Diseases

45.8

42.2

9.7

Non-communicable Diseases

42.2

42.8

78.4

Cerebrovascular Diseases

3.2

2.6

5.3

Ischemic Heart Disease

3.1

2.7

10.0

Injuries

11.9

15.0

11.9

Millions of DALYs

1,362

103

94

DALYS per 1,000 population

259

233

117

Adapted from reference 15.

Reliable morbidity data are among the most difficult to obtain in the developing countries of the Americas, yet they are critical in describing the burden of disease and in providing a compelling argument for mounting programs of health promotion and disease prevention. The need to collect comprehensive data describing morbidity and burden of disease will gain in priority as industrializing (and industrialized) countries have to cope with increasing health care expenditures.

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Risk Factors

Two types of risk factor data are collected depending on the context for their use: individual and community. Individual risk factor data are usually obtained through cross-sectional surveys. These are expensive undertakings so that larger surveys or cohort studies have been limited for the most part to North American populations. Some are conducted on a regular basis or at least more than once thus providing an indication of time trends, e.g. NHANES in the United States and the Nova Scotia Heart Health Survey in Canada. The Canadian Heart Health Surveys have served to formulate public policies for disease prevention. Conducted in 10 provinces and using standardized methodologies, these surveys have created the largest risk factor database of randomly selected individuals.16 Perhaps the most significant finding from this set of provincial surveys was that 63% of Canadian adults have at least one of the three major modifiable risk factors for CVD (smoking, cholesterol, high blood pressure). Furthermore risk factor prevalence across the country matched age-standardized mortality patterns for CVD. These findings have formed the basis for heart health initiatives aimed at reducing risk and preventing CVD.17

Risk factor data in patients with CVD are more widely available than in the general population, largely because of the ease of access to patients with relatively lower costs of data collection. The increasing involvement of Latin American centres in multinational studies provides a convenient and reliable source of comparative data. The recently completed FRICAS Study ("Factores de Riesgo Coronario en America del Sur") conducted in ten South American countries, including Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay and Venezuela is a significant example.18 Data from this study are forthcoming. An earlier study within Argentina described risk factor profiles in 1,000 men and women with an acute infarction and confirmed the importance of the major risk factors particularly for individuals in higher socioeconomic standing.19 This mirrors the association seen initially in North America but which now has reversed to higher risk in lower socioeconomic strata.

The association of the major risk factors including tobacco use, high blood pressure and hyperlipidemia with CVD is now well established in diverse populations in the Americas. There does not appear to be any paradoxical association in any population group, although admittedly not every ethnic and native population has been studied sufficiently. Even groups that have emigrated from countries with low prevalence and mortality from CVD, e.g. Japanese to the United States, have experienced an increased risk of CVD once exposed to the atherogenic lifestyles of the Americas.20 Where CVD mortality is increasing, it can be seen that the major risk factors are also prevalent.

In order to develop strategies for prevention it is important to identify not only patterns of risk factor distribution in the population but also enabling factors such as level of knowledge, attitudes and beliefs. Such measures will stimulate the development of explicit targets and goals at the same time providing parameters for measuring change. Likewise, data on community factors are integral to understanding the dynamics of lifestyle changes. Such data as yearly tobacco sales for example, although not collected by the health sector, can be useful in guiding programs and policies for CVD prevention.

 

Tobacco Use

Smoking was considered responsible for 400,000 deaths, 27.5% of which were due to lung cancer and 37.5% for CVD in the USA in 1985.21 In 1995 the number of deaths attributable to smoking rose to 529,000 (24% of all deaths).22 It is estimated that deaths attributable to smoking will increase 7 fold between 1995 and 2025 in the developing world.21 In Latin America, per capita consumption increased by about 20 percent between 1970 and 1985, with prevalence rates for smoking between 30 and 50% in men and between 10 and 30% in women.23 Overall smoking consumption in the adult populations of North America appears to have leveled off or is showing a decline, except among young females where there continues to be an increase.

Smoking in general is related to accessibility including favorable pricing, but among young people it is also a consequence of targeted marketing along with peer pressure. The majority of smokers begin their habit before 25 years of age. Although surveys of smoking prevalence are an indication of population risk, the critical measure particularly for monitoring the effect of tobacco-related policies is the uptake of smoking among young people. In Canada, surveys of youths aged 15 to 19 years, since the mid-1980’s show a relatively unchanging prevalence rate of about 21%, until 1990, after which there was an observable increase to 27% by 1994.24 This increase occurred as prevalence rates for current smoking by adults decreased through 1993. Such data do not reveal the full extent of the problem when statistical averaging is used or high risk populations are not included.

Smoking habits in Latin American and Caribbean countries need to be monitored with large prospective studies that will also examine the impact on mortality patterns over time. Targeted programs of prevention are dependent on current information especially for population subgroups. An important target population for smoking surveillance is that of health care providers themselves. As opinion leaders and role models, physicians in particular must reduce their own smoking prevalence to 0%, an issue that should be addressed in medical school. At present there is no systematic surveillance of smoking among medical students in the developing countries of the Americas and no interventive programs.

Diet and Cholesterol

In the Americas, diets have undergone changes that initially could be related to gross national product (GNP) with higher income being associated with increased consumption of sugars and fats derived from meat and milk products. This was the pattern observed in North America for most of this century. Urbanization is accompanied by a higher consumption of fats and animal products, refined sugars, polished grains, processed foods and "fast foods" including those provided by vendors for immediate consumption. In part as a consequence of affordability and perhaps also because of taste preferences, the proportion of all fat consumed that contributes to total energy is about 30%.25 In the last two decades there has been a reversal in the relationship between GNP and dietary preference, with higher income earners, particularly in North America shifting away from animal fats to vegetable fats, while trying to decrease total fat consumption and to a lesser extent from refined sugars to complex carbohydrates. At the same time, lower income populations throughout the Americas are adopting diets that are high in fats and sugars. There are a few exceptions, for example in Argentina, southern Brazil and Uruguay where rural dwellers still consume mainly cereals, legumes and other vegetables, and few animal foods.26

The most widely acknowledged measure of diet-related risk in the population is serum cholesterol, although defining normal values is arbitrary and subject to discussion. In Canada, 44% of the population (43% of women and 46% of men) has levels of total cholesterol of 5.2 mmol/L or greater.16 In the United States, 52.1% of the population has similarly elevated cholesterol levels.12 General population data in Latin America are not widely available and in all the Americas, trend data are either not available or difficult to interpret because of inconsistencies in measurement. However, where CVD mortality rates are high, the prevalence of cholesterol is also high. In Uruguay, 57.6% of men and 57.4% of women have an elevated cholesterol level. 27 In Mexico, hypercholesterolemia defined as > 240 mg% (6.2 mmol/L), is found in 8.9% of the population (10.0% men, 8.1% women).28

High Blood Pressure

High blood pressure remains a serious public health problem. In the United States of America, approximately 30 million people are treated for high blood pressure at a cost of over 8 billion dollars in direct costs for drug therapy alone.12 Just as for other risk factors, the prevalence varies by population group. Among non-Hispanic white adults, 20 years and older, 24.7% have high blood pressure. The prevalence among non-Hispanic blacks is 28.4% and among Mexican-Americans, 15.1%.12 For all three groups 60 years of age and older, the prevalence is increased to 60%, 71% and 61% respectively. In Canada, 16% of adults (19% men, 13% women) have either a diastolic blood pressure of > 90 mmHg or are being treated for high blood pressure.16

In Latin American countries, data are scanty and the definitions for high blood pressure are not always available. However from data derived from national surveys where high blood pressure was defined as > 140/90 mmHg, prevalence rates vary from 26.8% for men and 39.1% for women in Paraguay29 (overall 30%) to 25.1 % in Mexico28 and 6.4% in Uruguay27 for men and 28.5% in Mexico and 11.0% in Uruguay for women.

Surveillance of blood pressure, in addition to documenting the prevalence of the systolic and diastolic levels should also examine awareness and control. In Canada, 26% of the those with high blood pressure are unaware of their condition and of those aware, only 57% are treated adequately (to a level of diastolic pressure < 90 mmHg).16 Knowing socioeconomic and gender differences for awareness and control can help target appropriate interventions.

Physical Activity

Urbanization, and along with it mechanized transportation, are accompanied by a decrease in physical activity and fitness. This is seen in the established industrialized countries as well as in those that are rapidly industrializing. In a comparative study of urban and rural populations in Costa Rica, rural men and women scored significantly higher on fitness and generally weighed less with less total body fat than their urban counterparts. 30 Data from Porto Alegre, Brazil indicate that the level of physical activity relates to an individual’s socioeconomic position, particularly for men, where less privileged people often walk considerable distances to work.31 On the other hand, leisure time activities tend to be more prevalent among the educated and more affluent.

In Canada, the Heart Health Surveys revealed that 38% of Canadians, aged 18-74 reported a sedentary lifestyle (40% men, 36% women), with a higher prevalence (44%) among those who had only 11 years or less of education.32 There is a decline in physical activity with age except for those over 65 years who report more activity than those 45-64 years of age.

With urbanization there appears to be a decrease in physical activity especially during leisure time. As a result, increases in the prevalence of obesity, particularly abdominal obesity, high glucose and lipid levels are observed.33,34 In order to monitor changes in physical activity and compare findings in different populations, there is a need to adopt a universal measurement approach.

Future Needs for Surveillance of Risk Factors

Risk factor data in the less developed countries of the Americas are scarce and vary greatly in scope, context, and data collection method from one country to another. As funding is limited, there is a need to prioritize risk factors for surveillance, identifying a core set. Methodologies have to be standardized in order that meaningful comparisons can be made. Finally, a multinational survey, perhaps modeled on the INCLEN35 program, should be planned. To achieve this requires leadership and widespread collaboration.

Infective Causes

In spite of the transition towards a predominance of non-communicable CVD, infectious causes such as rheumatic fever and Chagas’ disease remain endemic in some countries of the Americas, particularly in rural locations. The prevalence of Trypanosoma cruzi in Latin American blood donors ranges from 7% in Santa Fe, Argentina to as high as 62% in Santa Cruz, Bolivia.36 The widespread existence of Chagas’ disease is not fully appreciated. In fact, except for Cuba and the Dominican Republic, Trypanosoma cruzi infection is seen in every hispanic country of the Americas. Less clear is whether the problem is contained or is spreading as time trends are not widely available.

Rheumatic fever and its related heart disease remains a major public health problem for children and young adults in developing countries. The prevalence of rheumatic fever and rheumatic heart disease is estimated to be 1.5/1000 (0.1-7.9) in the Americas, which is twice as high as the Western Pacific region but one third the rate seen in Africa.37 Nevertheless, the rate in Bolivia (7.9) is among the highest in the world.

Interventive Care

Surveillance of health care is increasing in importance as expenditures rise and consume a greater portion of the GNP. In the industrialized countries, in nearly all measures of health care expenditures, CVD rank the highest among diagnostic categories. In Canada, for which reliable accounting exists, the total (direct and indirect) costs were $19.7 billion in 1993. Including musculoskeletal disease ($17.8 billion), injuries ($14.3 billion) and cancer ($13.1 billion), these four noncommunicable diseases accounted for more than 50% of the total expenditures classifiable by disease category.38

The number of invasive diagnostic and interventive procedures continues to increase in Canada and the United States. Figure 2. In many of the developing countries, centres exist allowing patients to undergo the same procedures. In Cuba in 1994 there were 1700 diagnostic and 300 interventional catheterizations.39 In Uruguay, the number of cardiac catheterizations has tripled from 1551 in 1980/81 to 4629 in 1994.28 The rate of increase for cardiac surgery has averaged 9.2%/year over the same time span. Angioplasties began in 1992 but have more than doubled over the 3 years.

Practice patterns in Latin American countries are becoming known through participation in multicentre trials. Although limited to major centres, the diffusion of information particularly on the management of patients with acute ischemic syndromes has been rapid. In Argentina, for example, thrombolytic therapy was used in 12% of patients admitted with an acute myocardial infarction in 1987. By 1992, following participation in the ISIS-4 study, thrombolytic use had increased to 32%.40 Likewise in Uruguay, thrombolytic use increased from 5% in 1987 to 18% in 1991 and 23% in 1994.41 About 1990, a national protocol for the management of acute myocardial infarction was introduced, which probably also contributed to the increased use of thrombolytics as well as other drugs.

Conclusions

The epidemic nature of CVD was not fully appreciated in the industrialized countries of the Americas until mid century, when routine reporting of mortality provided sufficient data. Some twenty years later, a variety of interventions and preventive measures were underway, aimed at the multi-factorial nature of ischemic heart disease. Today there is incontrovertible evidence that the epidemic of CVD is also affecting populations in less developed countries of the Americas, where traditionally the greatest burden of disease derived from infectious agents. As industrialization begins to characterize these countries, there is a rapid transition from a rural and agrarian to an urban and industrialized lifestyle. During this period of transition, communicable diseases, such as rheumatic fever are still present while noncommunicable diseases, related to new lifestyles, begin to dominate. The most significant changes observed with these new lifestyles are widespread smoking beginning at an early age and increased fat consumption accompanied by a decrease in energy expenditure. There is a remarkable consistency in these epidemiologic patterns over time and across various populations.

At a time of fiscal constraints especially for health related expenditures, some may question whether epidemiologic surveillance is a necessary prerequisite to undertaking preventive measures. Indeed there are enough data to support aggressive programs of prevention in almost every country of the Americas, but the need for surveillance goes beyond describing the extent of the problem of CVD. Many countries do not yet have programs of prevention underway. Where efforts have begun, programs need to be monitored for their effectiveness and evaluated in terms of outcomes. Costly duplication of effort can no longer be justified and the need to compare data over time and between various populations calls for a consensus on variable definitions as well as on methodologies for data collection and analyses.42

Although it is widely acknowledged that there is lack of data in developing countries, systematic searches are revealing many sources of epidemiologic data.43 By organizing existing data, it is possible to profile diseases and risk factors in many populations thus providing an impetus for the development of programs of prevention.44 At the same time by identifying inadequacies and gaps in knowledge, initiation or improvement of surveillance programs will be stimulated. 

References 

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01/30/2000