Risk Factors and Prevalence of
Coronary Heart Disease in Puerto Rico
By MARIO R. GARCiA-PALMIERI, M.D., RAUL COSTAS,
JR., M.D.,
MERCEDES CRUZ-VIDAL, M.D., MARCELINO CORTES-ALICEA, M.D.,
ANGEL A. COLON, M.D., MANUEL FELIBERTI, M.D., ANGEL M. AYALA, M.D.,
DoLoREs PArrERNE, M.D., RAFAEL SOBRINO, M.D., RAQUEL ToRmRS, M.S.,
AND EMILIO NAZARIO, M.S.
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SUMMARY
In spite of an apparently increasing mortality rate from coronary heart disease in
Puerto Rico, the age-specific mortality rate from this illness is considerably lower in the
island than in the U. S. mainland. Examination of 9,814 Puerto Rican urban and rural
men in the 45 to 64-year age group revealed sizable and statistically significant differences in monthly income, cigarette smoking, ingestion of fats, blood pressure, heart
rate, relative weight, serum cholesterol, serum glycerides, prevalence of diabetes, and
prevalence of hypertension (lower in rural dwellers), and also in vital capacity,
consumption of calories per unit body weight, and physical activity (higher in rural
area). No urban-rural difference in coronary heart disease prevalence was found, but
the prevalence of definite myocardial infarction, established on basis of electrocardiographic criteria alone, was significantly higher in the 45 to 54-year urban group. Followup of this population to study incidence of disease and the influence of the various
factors upon the development of disease is being conducted.
Additional Indexing Words:
Diet
Blood pressure
Coronary heart disease
Epidemiology of coronary heart disease
Myocardial infarction
Urban-rural comparisons
Serum lipids
Prevalence of coronary heart disease
from this illness in the island than in the
United States. In 1963 the CHD death
rate per 100,000 persons for males 45 to
64 years of age was 202 for Puerto Rico and
679 for the United States.1 The reliability of
death certificate data in metropolitan San
Juan has been verified, leading credence to this
threefold difference in death rate. A 53%
autopsy rate of all deaths in this area in Puerto
Rico was helpful in validating death certificate
information.2 Furthermore, the International
Atherosclerosis Project has demonstrated less
severe atheromatous changes in the coronary
arteries of Puerto Ricans as compared to U. S.
continentals.3
Preliminary investigations conducted in
1964 on rural and urban Puerto Rican males,
aged 45 to 64, showed statistically significant
DURING the past 25 years the tropical
island of Puerto Rico has experienced
a transition from an agricultural to an industrial economy. Concomitantly, mortality
rates for coronary heart disease (CHD)
have increased. In spite of this, statistics
show a lower age-specific mortality rate
From the Department of Medicine of the School of
Medicine of the University of Puerto Rico, San Juan,
Puerto Rico.
This study was supported by Contract P. H. 43-63620 of the National Heart and Lung Institute, U. S.
Public Health Service.
Presented at the 42nd Scientific Sessions of the
American Heart Association, Dallas, Texas, November
14, 1969.
Received May 1, 1970; accepted for publication
May 20, 1970.
Circulation, Volume XLII, September 1970
541
GARCIA-PALMIERI ET AL.
542
differences in
some
characteristics claimed
to
be related to the development of CHD.4, 5
In view of the foregoing, a prospective
epidemiologic study, the Puerto Rico Heart
Health Program (PRHHP), was initiated to
confirm this low incidence and to search for an
explanation of it. The fact that two distinct
groups, rural and urban, had been identified
permitted exploration of possible differences
in factors which might influence the rate of
development of CHD in these subgroups of
the general population.
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Methods
The population selected for study was a cohort
of 10,000 males aged 45 to 64 at the time of
initial contact. This number would be expected
eventually to develop enough cases of CHD to
establish firm incidence rates and to demonstrate
significant differences in the factors under
investigation between those developing the disease and those remaining free of disease. Urban
and rural subjects were included in the population sample in a proportion of 2:1.
The communities selected are shaded in figure
1. Areas were classified as urban if located within
the San Juan metropolitan area and as rural if
located in the hilly interior. The latter were in
fact rural in character, agrarian and devoid of
large industry. All communities selected were at
PUERTO R1:0
NO:: RTHEAST MEDICAL REGIO
Figure
1
Communities under study. Urban
U and rural areas as R.
as
areas are
labelled
accessible distances from the University Hospital,
the site of the study.
A house-to-house census of all males aged 45
to 64 in the selected areas was conducted from
October 1964 to June 1965, yielding a total of
9,002 urban and 3,867 rural subjects. Persons
who died or moved outside the study area before
the initial appointment for examination and those
who could not be located after a thorough field
investigation of the residential cluster (probably
representing a census error) were eliminated from
the study list. After this depuration a study
population of 8,554 urban and 3,613 rural males
remained, for a total of 12,167 subjects. Technics
used for recruiting have been previously reported.'
The studies performed on respondents consisted of a social interview to determine education,
occupation, smoking habits, and physical activity;
a nutritional interview by the 24-hour recall
technic; a medical history with a thorough
investigation of cardiovascular symptomatology; a
physical examination aimed primarily at the
detection of cardiovascular, cerebrovascular, and
peripheral vascular abnormalities; vital capacity
measurement; a 12-lead electrocardiogram (ECG);
examination of urine for sugar and albumin; and
examination of blood for hematocrit, VDRL,
glucose, serum lactescence, light transmission, serum cholesterol, serum glycerides, and
lipoprotein electrophoresis. All information was
recorded on precoded forms. The details of the
operation of the clinic, of each study performed,
and the specific laboratory procedures utilized,
have been reported elsewhere.f-9
Clinical criteria for diagnosis of disease were
established'0 to ensure diagnostic consistency,
with separate criteria available for "definite" and
"possible" categories. Criteria were applied using
exclusively information obtained at the examination. Specific electrocardiographic criteria ensured
internal consistency in the interpretation of
tracings." These were read without reference to
the clinical data. Periodic checks of the reliability
of the ECG readings were conducted on a
subsample to test the comparability of interpretation among the electrocardiographers and their
adherence to the criteria.
Laboratory quality control measures included
duplication of samples, blinded reintroduction of
laboratory samples by the laboratory supervisor,
repeated analysis of pooled sera, participation in
the proficiency programs of the National Communicable Disease Center in Atlanta, Georgia
(NCDC), periodic exchange of samples with the
Framingham and National Institutes of Health
Laboratories, daily introduction of double-blind
samples by the statistician, periodic analysis of
commercial samples of known values, and
Circulation, Volume XLII, September 1970
CORONARY HEART DISEASE IN PUERTO RICO
543
Table 1
Number of Subjects Receiving an Appointment,
Number Examined, and Response Rate
With appointment
Total urban
Total rural
Grand total
8554
3613
12,167
Exarnined
Rate
(%)
6838
2976
9814
79.9
82.4
80.7
participation in the quality control program
specifically designed by NCDC for the Epidemio-
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logical Heart Disease Projects.7 All information
obtained was key punched and submitted to
analysis at the Computer Center.
The first examination cycle was started in May
1965, with the aim of examining at least 80% of
the enumerated individuals, and was completed
in December 1968. The present report is
concerned with the findings including coronary
risk factors, other relevant population characteristics, and the prevalence of CHD, specifically
myocardial infarction (MI), with special emphasis on urban-rural differences between men aged
45 to 54 and 55 to 64.
Results
Of a total of 12,167 males who received an
appointment, 9,814, or 80.7% of the whole
group were examined. Eighty per cent of the
urban and 82.4% of the rural males were
evaluated (table 1).
At examination 2,580 rural and 6,205 urban
men were confirmed to have been in the 45 to
64 age group when enumerated (table 2). The
discussion which follows concerns subjects
free of CHD according to established criteria'0 in the age groups 45 to 54 and 55 to 64.
These include 2,414 rural and 5,791 urban
men. The rural population had lower economic resources than the urban group (fig. 2).
A number of significant differences in
Table 2
Number of Urban and Rural Men Examined,
Classified by Age Groups
Total
9814
Total subjects examined
346
Subjects aged under 45
4922
Subjects aged 45-54
3863
Subjects aged 55-64
Subjects aged 65 and over 683
Circulation, Volume XLII, September 1970
Rural
Urban
1298
1282
3624
2581
ol -
.18 1J99-Bo
RURAL
AGE
URBAN
URBA
RURAL
55-64
45-54
Figure 2
Monthly income in dollars in men free of CHD by
age groups and site of residence.
personal attributes was observed when comparing rural and urban subjects in the
population sample.
A physical activity index (PAI) was calculated by adding the products of weighted
hours spent in five specified degrees of
activity.'2 A significantly higher degree of
activity was observed in the rural than in the
urban male (table 3).
There were more cigarette smokers in the
rural area, although the percentage of heavy
smokers was higher in the urban population in
both age groups (table 4).
Relative weights were determined from the
ratio of the observed weight to the ideal
weight for the observed height, expressed as
per cent. The ideal weight was taken from
Metropolitan Life Insurance tables. By this
Table 3
Mean Values and Standard Error of Physical
Activity Index in Urban and Rural Men Free of
CHD by Age Groups: The Difference Between
Rural and Urban Men is Significant at the 1%
Level
Age
(yr)
45-54
55-64
Rural
Mean
BE
Urban
SE
Mean
38.8
37.5
0.3
0.3
31.4
31.2
0.1
0.1
P
<0.01
<0.01
GARCIA-PALMIERI ET AL.
544
Table 4
Per Cent Smokers and Degree of Smoking Among Urban and Rural Men Free of
CHD by Age Groups. Differences Are Significant at the 1% Level
Age, 45-54
Total subjects
Present smokers
Heavy smokers*
Age, 55-64
Total subjects
Present smokers
Heavy smokers*
Rural
Urban
1231
663 (54%)
(11%)
3419
1572 (46%)
1181
550 (47%)
( 7%)
2361
841 (36%)
P
<0.01
<0.01
(24%)
<0.01
<0.01
(21%)
*From total present smokers.
AGE
45-54
40-
55-64
40-
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NO x SD
-RURAL 1228 105 15,8
----URBAN3419 117 I78
NO x SD
-RURAL 1170 03 15.6
----URBAN 2383 114 18.9
30
301
20
20-
\N
IN
I
_
I
10
II
-1
(I
50
I
I
10I
I
1-
i
I
100
11
I
150
7
I
200
50
i1o
I5o
200
RELATIVE WEIGHT
Figure 3
Distribution
curves
of the relative weight of urban and rural
criterion, distribution curves showed urban
to be considerably heavier (fig. 3).
The percentage of individuals with a total
vital capacity above 3.4 L was significantly
higher in rural men in both age groups
(fig. 4).
Mean values of systolic and diastolic blood
pressures and heart rate in both age groups
were substantially and significantly higher in
the urban population (table 5). The percentage of individuals with a systolic blood
pressure of 160 mm Hg and a diastolic of 95
mm Hg and above was twice as high in urban
males, while bradycardia of less than 60
beats/min predominated in the rural group
men
free of CHD by
age groups.
men
(fig. 5). These differences are statistically
significant. Applying the established criteria
for definite and borderline hypertension,1 the
prevalence of hypertension was statistically
o
AGE
L.....
45-54
&
I
3DC.
-- -. .55-64
,
Figure 4
Irotal vital capacity more than 3.4 L in urban and
rural men free of CHD by age groups.
Circulation, Volume XLII, September 1970
CORONARY HEART DISEASE IN PUERTO RICO
545c
Table 5
Mean Values and Standard Error of Systolic and
Diastolic Blood Pressures and Heart Rate in
Urban and Rural Men Free of CHD by Age
Groups. All Diferences are Statistically Significant
at the 1% Level
Rural
SE
Mean
Age
(yr)
Urban
Mean
BE
P
Systolic blood pressure (mm Hg)
0.3
132
0.6
125
0.5
139
0.7
131
Diastolic blood pressure (mm Hg)
84
0.2
0.3
80
0.3
84
81
0.3
Heart rate (beats/min)
74
0.2
0.4
69
74
0.3
0.4
68
45-54
55-64
45-54
55-64
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45-54
55-64
<0.01
<0.01
<0.01
<0.01
AGE
45-54
55-64
45-54
55-64
POSSIBLE
DEFINITE
Figure 6
Per cent prevalence of "definite" and "possible" hypertension in urban and rural men free of CHD by age
<0.01
<0.01
groups.
;
ED
AE
0O
RURAL
URBAN
45-54
significantly higher in urban males in both age
groups (fig. 6).
Table 6 shows the mean values for diet
variables between rural and urban males by
age groups. Although the total ingestion of
calories was practically identical in both rural
and urban men, ingestion of calories per
kilogram of body weight, percentage of
calories from carbohydrates, the ratio of
complex to simple carbohydrates, and salt
ingestion were higher in rural males. The
ingestion of saturated fat, the percentage of
calories from fat and the ratio of polyunsaturated to saturated fatty acids in the diet (P/S
ratio) were higher in urban males. This holds
for both age groups.
55-64
0
10
20
30
BYSIOLIC
BP
160
aleero
DIASTOLIC
BP
95+
HEART RATE
<6o
Figure 5
Per cent prevalence of systolic blood pressure 160
mm Hg or more, diastolic blood pressure 95 mm Hg
or more, and heart rate less thin 60 beats/min in
urban and rural men free of CHD by age groups.
Table 6
Mean Values for Diet Variables in Urban and Rural Men Free of CHD by Age Groups.
There were Significant Differences in All Variables Except Caloric Intake
Rural
1231
No. of subjects
2460
Calories
39
Cal/kg weight
35
Sat. fat
0.33
P/S ratio
33
%O cal from fat
% cal from CHO (u.c.) 51
3.5
C/S ratio
32
Salt index
Circulation, Volume XLII, September 1970
Age: 45-54 yr
Urban
3423
2499
35
38
0.50
37
45
2.5
28
P
Rural
Age: 55-64 yr
Urban
-
1183
2366
0.19
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
2234
37
31
2272
33
34
0.34
32
52
3.3
29
0.49
36
47
2.7
26
P
0.19
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
GARCIA-PALMIERI ET AL.
,546
Table 7
Mean Values and Standard Error of Blood Glucose in Urban and Rural Men Free of CHD by
Age Groups
Age
(yr)
Rural
Mean
(mg/lOOml)
SE
45-54
55-64
Total
92.6
92.3
92.5
0.7
0.6
0.5
Urban
SE
Mean
(mg/lOOml)
96.4
99.6
97.7
0.5
O.8
0.4
P
<0.01
<0.01
<0.01
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The mean blood glucose value was substantially higher in urban males, and the difference is statistically significant (table 7).
Applying the established criteria for definite
diabetes,'0 a statistically significant, twofold
higher prevalence of diabetes was found in
urban men in both age groups (fig. 7).
Both mean serum cholesterol and serum
glycerides were higher in the urban group
(table 8). An unusual finding was the
association of normal cholesterol with high
glyceride levels in the 45 to 54-year-old urban
men. Since both fasting and nonfasting cholesterol values had practically identical means
and standard deviations all are included in
the table. However, since the nonfasting state
may affect the glyceride level, only the 4,917
fasting specimens are included. The glyceride
values were markedly high in urban subjects
under age 55; in those 55 to 64 they were
considerably-lower.
Table 8
Mean Values and Standard Error of All Serum
Cholesterol and Fasting Glyceride Levels in Urban and Rural Men Free of CHD by Age Groups
Age
(yr)
Rural
Mean
SE
45-54
55-64
Total
45-54
55-64
Total
Urban
Mean
SE
Cholesterol (mg/100 ml)
207
0.7
202
0.9
1.1
195
1.1
196
196
0.8
Glycerides-fasting
127
3.5
130
3.0
129
2.0
205
0.6
(mg/lO
1ml)
171
3.3
147
2.7
161
2.2
45-54
55-64
Figure 7
Per cent prevalence of "definite" diabetes in urban
and rural men free of CHD by age groups.
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
The distribution of high and low serum
cholesterol and glyceride levels between the
total rural and urban populations is illustrated
in figure 8. The percentage of subjects with a
cholesterol level less than 175 mg/100 ml is
higher in the rural group, while at levels of
250 mg/ 100 ml and over urban males
predominate. A similar situation occurs when
comparing the percentage of subjects with low
and high levels of glycerides using 100 and
160 mgl 100 ml, respectively, as breaking
points. The mean hematocrit level was similar
for both rural and urban groups.
A comparison of all CHD and definite CHD
prevalence by established criteria'0 between
rural and urban dwellers by age groups is
LESS THAN IT5
250 a OVER
CHOLESTEROL
AGE
P
LESS THAN 100
160 a OVER
CLYCERIDES- FASTING
3
RURAL
MI
URBAN
Figure 8
Per cent prevalence of low and high cholesterol and
glyceride levels in urban and rural men aged 45 to
64 years who were free of CHDCirculation, Volume XLII, September 1970
CORONARY HEART DISEASE IN PUERTO RICO
Table 9
Prevalence Rates* of All CHD and Definite CHD
in Urban and Rural Men by Age Groups
All CHD
45-54
55-64
Definite CHD
45-54
55-64
Rural
Urban
Total
47.9
76.4
54.1
82.6
52.6
80.6
12.3
30.4
20.4
32.6
18.4
31.9
*Per 1,000 males.
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shown in table 9. No difference was encountered. "All CHD" includes definite and possible
myocardial infarction (MI), coronary insufficiency, and angina pectoris, while "definite
CHD" excludes the possible infarctions.10
However, when comparing definite MI, which
is established solely on the basis of electrocardiographic criteria, the most reliable method, the prevalence is significantly higher in the
younger urban group than in the corresponding rural group.
Table 10 illustrates the prevalence of
definite MI and all CHD in the United States
and Puerto Rico as revealed by the National
Health Survey and the PRHHP, respectively.
The criteria used in both studies are comparable. Prevalence of CHD is strikingly lower
in Puerto Rico, especially in the MI group in
which the diagnosis depends upon electrocardiographic criteria.
Discussion
Puerto Rico is in the unique position of
Table 10
Prevalence Rates* of All CHD and Definite MI
in the Puerto Rico Heart Health Program and in
the U. S. National Health Survey
U.S. (NHS) 1960-62
Definite MI
45-54
55-64
All CHD
45-54
55-64
*Per
1,000
PRHHP 1965-68
19
43
5
8
69
141
53
81
males.
Circulation, Volume XLII, September 1970
547
having achieved in a relatively short period of
time a high degree of industrialization.
Although the expected drop in infectious
disease death rates which accompanies industrialization has occurred, the concomitant
relative and absolute increase in the death rate
from degenerative diseases has not quite kept
up with the expectations. Deaths from cardiovascular disease in general and from coronary
heart disease in particular are lower compared
to figures in other developed areas.
The present prospective epidemiologic
study of CHD in Puerto Rico, which is limited
to urban and rural men, 45 to 64 years old,
was started in May 1965. An overall 80.7%
response rate in the first examination cycle
was obtained. The quite similar response rate
of both rural and urban dwellers and the large
number of subjects studied permits internal
comparisons between these two populations
by age groups. Analysis of the social, medical,
nutritional, and biochemical habits and characteristics reveals differences in attributes
usually related to the development of CHD.
The specific findings presented here are also of
value for external comparison with other
populations concerning the relative influence
of specific characteristics in the development
of CHD.
A rural Puerto Rican with a lower monthly
income was expected, as rural males have
lower educational levels than urban dwellers
and are dependent on an agricultural economy with a high percentage of laborers,
whereas urban dwellers are dependent upon
an industrial economy and a strong middle
class.
The physical activity index was higher in
the rural men. The type of work performed
can to a large extent account for this. Another
important factor is that these subjects reside in
hilly areas with poor avenues of communication and limited roads, a situation which
forces them to walk to work every day. Even
when visiting their next-door neighbor, who
may live as much as 1 km away, they must
walk.
Although more rural subjects were cigarette
smokers, the number of heavy smokers was
548
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higher in the urban group. Whether the
stresses of urban life or a greater accessibility
of funds are responsible for the latter remains
moot.
Although the total caloric intake was similar
in urban and rural males, the relative weight
of the urban men was higher and their
ingestion of calories per unit of body weight
was lower. The higher physical activity level
of the rural men may be partially responsible
for this difference.
A significantly higher prevalence of hypertension was noted in urban dwellers. Since
hypertension is a potent precursor of CHD, it
will be important to determine the relation of
this parameter to the rate of development of
CHD in urban and rural populations at risk. It
is interesting that although hypertension was
more prevalent in the urban area, rural men
had a higher consumption of salt in the diet.
The lower heart rate and the higher
prevalence of bradyeardia in rural males may
be due in part to the greater physical activity
of this group.
Total ingestion of calories was similar in
corresponding age groups. The higher consumption of calories per kilogram of body
weight in the rural group is not unexpected, as
they have a significantly lower relative weight
and more physical activity. Although the
urban group had a higher consumption of
saturated fat and a higher percentage of
calories from fat, they also had a higher P/S
ratio to counterbalance it.
No ethnic differences between rural and
urban men could be identified to account for
the higher mean glucose level and prevalence
of diabetes in the urban group. The possibility
that the greater obesity of the urban as
compared to the rural man to some extent
may account for this must be evaluated
further. Disordered lipid metabolism as reflected by the urban-rural difference in
hyperlipidemia is another possibility worth
exploring. Analysis of the lipoprotein electrophoresis may also shed more light on this
possibility.
Although, compared to the U. S. mainland,
GARCIA-PALMIERI ET AL.
mean cholesterol levels were low in both the
rural and urban males, sizable and statistically
significant differences were found between
them. In contrast, rural men had normal
serum glycerides while these lipids were
distinctly elevated in urban males. The latter
group, then, comprises a low cholesterol high
glyceride population, an unusual finding that
may help elucidate the CHD disease potential
of glyceride in the face of relatively normal
serum cholesterol values. An examination of
extreme values reveals a larger group of individuals with both low glyceride and cholesterol levels in the rural group. The
possibility that subclinical malabsorption may
account for some of the extremely low
cholesterol values in rural subjects seems likely
in view of the findings encountered in a
limited study of intestinal absorption by
different laboratory technics conducted on a
subsample of men with low cholesterol
levels.13
In spite of the striking rural-urban differences on the findings discussed above, the
total prevalence of CHD is not different. It
will be of interest, therefore, to observe the
relation of these parameters to the rate of
development of clinically overt CHD in the
urban and rural population subgroups.
The fact that definite MI, which is established on the basis of more objective electrocardiographic criteria, is significantly higher in
the younger urban group as compared to the
respective rural group could be the result of
the observed urban-rural differences. It raises
interesting questions concerning what may be
happening to the life style of the younger
Puerto Rican in urban areas concerning
patterns of living, dietary habits, stresses of
life, and the prevalence of diseases such as
hypertension and diabetes.
Comparison with fully industrialized countries, such as the United States, shows a lower
prevalence of CHD in Puerto Rico. If the
responsible factors are identified this would
have considerable relevance for implementing
appropriate preventive measures to avoid a
further increase in CHD mortality in Puerto
Circulation, Volume XLII, September 1970
CORONARY HEART DISEASE IN PUERTO RICO
Rico. It would also contribute to an understanding of similar problems in other countries.
Acknowledgment
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We are specially indebted to Dr. William Zukel,
Associate Director for Epidemiology and Biometrics
of the National Heart and Lung Institute, and Dr.
William B. Kannel from the Framingham Study for
their supervision and continuous advice, without which
the Puerto Rico Heart Health Program could not have
been accomplished. We also acknowledge the
cooperation of Mr. Harold Kahn, Mrs. Jeanne Truett,
Miss Patricia M. MacNamara, and Miss Jeanne
Tillotson who have contributed in different aspects of
the study. We also thank Dr. William B. Kannel for
reviewing this manuscript.
We express our appreciation to Miss Eda Gayta
Miss Maresa Rodriguez, Miss Edna Cordero, and all
the technical and clerical staff who have contributed
to the success of this study.
References
1. GARCIA-PALMIERI MR, FELIBERTI M, COSTAs R
JR, ET AL: An epidemiological study on
coronary heart disease in Puerto Rico: The
Puerto Rico Heart Health Program. Bol Asoc
Med P Rico 61: 174, 1969
2. GARCIA-PALMIERI MR, FELIBERTI M, CosTAs R
JR, ET AL: Coronary heart disease mortality: A
death certificate study. J Chron Dis 18:
1317, 1965
3. GALINDO L, AREAN V, STRONG JP, ET AL:
Atherosclerosis in Puerto Rico: Study of early
aortic lesions. Arch Path (Chicago) 72: 367,
1961
4. BLANTON JH, RODRIGUEZ M, COSTAs R JR, ET AL:
A dietary study of urban and rural males in
Puerto Rico. Amer J Clin Nutr 18: 169,
1966
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5419
5. BENSON H, COSTAs R JR, GARCiA-PALMIERI
MR, ET AL: Coronary heart disease risk
factors: A comparison of two Puerto Rican
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Downloaded from http://circ.ahajournals.org/ by guest on June 15, 2017
Risk Factors and Prevalence of Coronary Heart Disease in Puerto Rico
MARIO R. GARCÍA-PALMIERI, RAÚL COSTAS, JR., MERCEDES
CRUZ-VIDAL, MARCELINO CORTÉS-ALICEA, ANGEL A. COLÓN, MANUEL
FELIBERTI, ANGEL M. AYALA, DOLORES PATTERNE, RAFAEL SOBRINO,
RAQUEL TORRES and EMILIO NAZARIO
Circulation. 1970;42:541-549
doi: 10.1161/01.CIR.42.3.541
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