Epidemiologic Aspects of Asthma
in Latin America*
Edgardo Carrasco,
M.D.,
EC.C.P.
The prevalence of asthma in Latin America is reviewed.
There are many limitations to using official national statistics, and the data presented are from surveys of restricted
populations in Uruguay, Peru, Mexico, Brazil, Venezuela,
Argentina, and Chile. Asthma prevalence appears to be
quite variable, ranging from 0.4 percent in Peru to 4.3
percent in Brazil. As reported elsewhere in the world, in
children rates were higher in boys than girls, and elderly
asthmatic patients have higher rates. Further information
on the clinical and etiologic characteristics of asthma in
Latin America are presented from a survey of chronic
allergic disease conducted in seven Latin American countries. Pre-coded forms were completed during consultations
at cooperating allergy departments, and all were analyzed
centrally at the Pan American Health Organization. Eightysix percent of the patients studied were atopic and 46
percent of asthmatic patients had a history of other associated allergic conditions (allergic rhinitis, atopic dermatitis).
This is higher than reported for developed countries.
T
he population of Latin America was 378,000,000 in 1982.
As a result of an expected annual increase of 2.7 percent
there will be 620 million inhabitants in the year 2000. The
majority of the population lives under deficient sanitary
conditions. Healthcare services are generally insufficient,
with coverage of government-organized health services varying from 20 to 90 percent.
1
Latin America covers a vast area. Crossed by the equatorial
fine and both tropics, its climate is extremely variable;
tropical (southern North America, Central America and
northern South America), altiplanic (part of Peru, Bolivia and
northern Chile), desert (north of Chile), temperate (southern
South America, ie, central Chile, Argentina and Uruguay)
and cold (southern Chile and Argentina). These climatic
differences, together with the varied racial compositions of
Latin American countries, might suggest a wide fluctuation
in the prevalence of asthma in different Latin American
countries.
Unfortunately, there is a paucity of vital statistics for Latin
America. It is therefore very difficult to find reliable rates of
incidence, prevalence and mortality for asthma, and the necessary data to ascertain the impact of this disease on the
health resources. Reports on the epidemiology of asthma in
Latin American countries are sparse. The few available are
not comparable due to differences in methodology employed
and ages of the populations surveyed.
Use of the official vital statistics has many shortcomings.
Countries have very different health service structures and
types of health registries and data are of variable reliability.
This makes inter-country comparison very difficult. Unreliability of data on mortality and morbidity rates within many
Latin American countries also means that extrapolation to
the general population would not be appropriate.
Mortality rates for asthma are in general of little help in
epidemiologic studies in Latin America. Information given
on death certificates is inaccurate and not always completed
by a physician. While these certificates account for deaths in
and outside hospitals, pertinent circumstances associated
with death are not recorded.
Population surveys offer the most satisfactory approach to
evaluation of the prevalence of asthma. However, analyses
utilizing vital statistics are limited because of inconsistencies
in the participation of many different medical practitioners
and vagueness in the use of terminology for a disease as
variable as asthma.
This review is based primarily on the analysis of prevalence surveys done in restricted Latin American populations
within the few countries that have published their experiences. The results of a cooperative study headed by the Pan
American Health Organization (PAHO) conducted in 1980
through 1981 are also reported. This study involved eight
different cities in seven Latin American countries and employed a uniform protocol. The aim of the study was to
explore characteristics ofpatients that seek medical attention
for chronic allergic diseases including bronchial asthma,
allergic rhinitis and atopic dermatitis. The findings of this
survey illuminate certain aspects of asthma in selected areas
of Latin America.
2
P R E V A L E N C E SURVEYS O F ASTHMA
The magnitude of asthma and its burden on the health
services can be evaluated by community-based studies based
on a variety of approaches ranging from a simple questionnaire to detailed inquiry supplemented by measurement of
respiratory function, allergen skin testing and bronchial
airway hyperreactivity. Field surveys in Latin America are
sparse. Various general populations have been surveyed after
a careful census. These include Barros Blancos, Uruguay;'
Lima, Peru; Monterrey, Mexico; Ribeirao Preto and Porto
Alegre, Brazil; Coche and San Juan de Manipiare, Venezuela and Santiago, Chile. Others in Caracas, Venezuela;
Rosario, Argentina; Santiago, Chile; Montevideo, Uruguay and Cordoba, Argentina have conducted prevalence
surveys in school populations. As in other parts of the world,
methods used in Latin America have not been uniform. Some
have published data of actual prevalence
while others
estimated prevalence for a period, cumulative prevalence" or combinations of these.
3
1
5
6
7
8
8
10
11
12
14
13
15
16
4,910
13
14
13,14
Tables 1 and 2 summarize the characteristics and results of
these studies. The highest prevalences of asthma in surveys
of a general population have been reported in Brazil (4.3
percent for Porto Alegre and 2.9 percent for Ribeirao Preto),
which are of a similar magnitude to those reported for many
Western countries. Intermediate figures of 1.15 and 1.3
percent have been reported for Monterrey, Mexico and
Barros Blancos, Uruguay. The Brazilian studies are not
comparable because they were conducted in populations of
different age ranges; 35 to 80 years and three to 65 years in
Porto Alegre and Ribeirao Preto, respectively.
Countries with high figures for interethnic breeding and
large indigenous populations, as in Peru, Chile and Mexico,
have the lowest prevalence of asthma (0.4, 0.5 and 1.15
percent respectively). This has been reported previously for
primitive societies,
Mexican/American school chddren,
and developing countries in general and is suggestive of a
17,18
*From the National Institute of Chest Diseases, Santiago, Chile.
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19
93S
Table 1—Asthma Prevalence Surveys in Latin America: Results of Studies in General Population
Type of prevalence
Country
Period of
study
Uruguay
1970
Oan-April)
Peru
1971
(May-June)
Mexico
1978
(Spring)
Brazil
1979
0une-July)
Chile
Age
(years)
Barros
Blancos
(suburban)
Lima
(central-urban)
Lince
(residential)
Monterrey
(urban)
0-65 +
Ribeirao
Preto
(urban)
Porto Alegre
(urban)
•
'
Actual
%
M/F
1,525
1.30
1.5:1.0
0-65 +
2,645
0,70:1.0
0-65 +
992
0-70 +
1,968
0.40
(4.4)*
1.20
(4.3)*
1.15
3-65 +
3,353
35-80 +
0.93:1.00
0.70:1.00
Methodology
Author
Questionnaire
Portillo et al
Questionnaire
Flow meter.assess
Atmosph contam
Narvaez
Questionnaire
chronic allergic
diseases
Padronized
Questionnaire
Leal et al
6
Carvalho Ramos
0.23:1.00
0.38:1.00
0.60:1.00
Questionnaire
Flow meter
measurement
Chaieb et al
0.88:1.00
Isturiz
1.00:0.90
Questionnaire
Parasitologic
examination
Total IgE
Questionnaire
Medina
Coche
Island
0-50 +
1983
San Juan de
Manipiare
(rural)
Santiago
(urban)
0-50 +
1,040
2.50
(5.5)*
0-65 +
2,820
0.50
4
5
4.70
4.90
2.50
4.30
2.80
(20.4)*
1982
1983
(Nov)
1.0:0.6
2.40 M
3.40 F
316t
102*
122§
54011
2,531
1980
(Feb-April)
Venezuela
Population
studied
Size of
sample
(persons)
7
8
9
10
*Respiratory symptoms.
tSmokers.
tEx-smokers.
§Non-smokers.
UTotal population.
possible role of a racial genetic factor.
The influence of sex on the prevalence of asthma is not
clear and varied considerably between surveys. There was,
as previously reported, a tendency towards higher figures
for asthma in females in older age groups, with the exception
of Uruguay and Peru. Higher prevalence figures for asthma
in older ages, however, may be due to a diagnostic problem
resulting from confusion with other chronic respiratory
diseases and the use of non-adjusted age rates even though
these countries have different population age structures.
20
The Venezuelan study of the Island of Coche, where
residents primarily are engaged in fishing, and the rural town
of San Juan de Manipiare examined the association of
parasitic infection in the population (67.5 percent) and
elevated total IgE (average 1,000 UI) with the prevalence of
asthma and chronic respiratory obstructive disease. It has
been reported
that populations with high prevalence of
parasitic infections that are associated with high values of
total IgE have lower prevalence rates for asthma. However, in
spite of a significantly higher prevalence of respiratory
symptoms in the Coche Island than Manipiare (20.4 to 4.38
percent), cumulative prevalence of asthma was similar for
both localities (2.8 and 2.5 percent respectively).
9
2122
The survey in Porto Alegre did not show any greater
prevalence of asthma in smokers; this seems to be in agreement with other published reports. The difference observed between smokers and nonsmokers (4.7 and 2.5
8
23
percent respectively) was not statistically significant and
could not be attributed to atmospheric contamination.
The difficulty in precisely diagnosing asthma is demonstrated by the figures given for Peru and Venezuela (Table 1).
The values could be much higher if more liberal diagnostic
criteria were applied.
The surveys of school children (Table 2) show higher
prevalence figures than in the general population, as has
been reported in Western countries. Rates vary from 2.7
percent in Chile to 7.5 percent in Uruguay. This level of
variation is in accord with the literature," in which prevalences from 0.8 to 11 percent and even as high as 17 percent
have been reported. Such differences observed in Latin
America might be explained by the different age structure of
the populations studied and the different countries involved
and the common use of the term asthma to describe a wheezing episode regardless of cause. There seems to have been no
attempt to distinguish between true asthma, wheezing
bronchitis and asthmatic bronchitis as stressed in the literature. This situation is particularly evident in the survey
in Cordoba, Argentina where the prevalence of asthma
varied from 2.9 to 16.8 percent, depending on whether
wheezy bronchitis and asthmatic bronchitis were included
under the term "asthma."
28
29
30
2831
Studies in Europe have consistently found a higher prevalence in men than women.
In surveys of Latin America,
this was only shown clearly for Chile.
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24 2 7 , 3 2
13
International Workshop on Etiology of Asthma
Table 2—Asthma Prevalence Surveys in Latin America: Studies in School Children
Type of prevalence
Period of
study
Age
(years)
Sample
Actual
size
<*)
M/F
tive (%)
M/F
Methodology
Caracas
(urban)
Rosario
(urban)
3-15
1,968
3.5
1.2:1.0
11.4
1.2:1.0
Questionnaire
Benaim Pinto"
6-13
3,257
5.6
Questionnaire
Crisci'
Santiago
(urban)
Montevideo
(urban)
6-14
2,759
2.7
2.3:1.0
5.4
2.2:1.0
Questionnaire
Valenzuela et al'
Uruguay
1979
(Aug-Sep)
1981
11-16
4,296
7.5
1.1:1.0
12.4
1.1:1.0
Questionnaire
Schuhl et a l "
Argentina
1980
Cordoba
6-12
977
Questionnaire
IgE total
Prick test to
house dust
Bustos et a l "
Country
Venezuela
1961
Argentina
0an-Feb)
1968
Chile
Population
studied
Cumula-
2.9
(16.8)*
*Wheezy bronchitis and asthmatic bronchitis are included.
CLINICAL AND ETTOLOGIC CHARACTERISTICS
Between July 1, 1980 and July 31, 1981, a survey of the
prevalence of chronic allergic disease (asthma, rhinitis and
atopic dermatitis) was done in seven countries of Latin
America under the sponsorship of the Pan American Health
Organization (PAHO).
Brazil, Colombia, Chile, Mexico (Monterrey and Mexico
City), Peru, Uruguay and Venezuela participated. The specific objectives of the study were: 1) to document the
characteristics of the patients seeking attention at specialized
allergy centers; 2) to determine the relative importance of
genetic, environmental and emotional factors in the precipitation and modification of allergic diseases; 3) to demonstrate the functional impairments resulting from chronic
allergic diseases in some Latin American countries; and 4) to
evaluate the type and extent of the medical demand by
chronic allergic disease patients. For this purpose, asthma,
allergic rhinitis and atopic dermatitis were defined and 200
consecutive consultations to allergy departments in the
2
Authors
2
designated cities and countries were analyzed. However, the
survey was not designed to evaluate incidence or prevalence
of chronic allergic diseases within the community.
Specifically designed and pre-coded forms were completed at local levels and carefully reviewed by the principal
investigators. Reports were sent to PAHO offices in Washington, D.C. for computer analysis and filing in a central data
bank- A total of 2,678 forms were obtained and a descriptive
analysis of the characteristics of the sample was done.
Table 3 shows the relative contributions of the eight
participating centers and the total number of patients and
clinical diagnoses reported. The most frequent diagnosis was
combined allergic disease (46 percent), followed by the single
disorders of allergic rhinitis (29.2 percent), asthma (18.6
percent) and atopic dermatitis (6 percent). Through combined diagnosis, there is a clear linkage of asthma to other
atopic disorders. This finding appears to be in agreement
with previously reported studies.
33
Of the 498 cases of asthma in the study, 152 patients (30.5
percent) were in the age range of zero to four years and 115
Table 3—Collaborative Study of Chronic Allergic Diseases PAHO 1983: Distribution of Patients Related to Countries
and Diagnosis
Diagnosis
Country
Brazil
Chile
Colombia
Monterrey
Mexico D. F.
Peril
Uruguay
Venezuela
Total
Observed
values
Number
% of total
Number
% of total
Number
% of total
Number
% of total
Number
% of total
Number
% of total
Number
% of total
Number
% of total
Number
% of total
Asthma
Rhinitis
Eczema
Combined
Others
33
1.23
89
3.32
21
0.78
35
1.31
61
2.28
63
182
6.80
1
0.04
0
0.00
31
1.16
151
5.64
0
0.00
0
0.00
10
0.37
87
3.25
18
0.67
140
5.23
94
3.51
16
0.60
498
18.60
261
9.75
32
1.19
47
1.76
78
2.91
86
3.21
782
29.20
3
0.11
34
1.27
5
0.19
69
2.58
18
0.67
161
6.01
381
14.23
72
2.69
105
3.92
6
0.22
327
12.21
1,226
45.78
0
0.00
0
0.00
0
0.00
1
0.04
0
0.00
11
0.41
2.35
121
4.52
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Total
132
4.93
271
10.12
395
14.75
732
27.33
156
5.83
297
11.09
248
9.26
447
16.69
2,678
100.0
95S
Table 4—Collaborative Study of Chronic AUergic Diseases
PAHO 1983: Frequency of Asthmatic Episodes
Percent of
total
Frequencv
Previous
episodes
(no)
2.61
15.66
16.06
42.97
22.69
100.00
13
78
80
None
Daily
Weekly
Monthly
Other
Total
214
113
498
patients (23.1 percent) in the range of seven to 19 years; 83
(16.7 percent) were between 20 and 34 years and 148 (29.7
percent) were aged 35 years or more. Positive family histories
for allergy in parents, brothers, sisters, and children were
observed in 285 (57.7 percent) of the cases of asthma. In 54
cases the antecedent was unknown (15,7 percent) and in 155
patients (21.95 percent) there was no known history of allergy
in the family.
Table 4 shows the relative frequency of the reported
asthmatic episodes. Only 13 (2.6 percent) of the 498 cases
were referred for a first episode; 78 (15.6 percent) had
complained of daily symptoms; 80 (16.06 percent) of weekly
attacks, and 214 (42.9 percent) one episode every month.
The survey also analyzed data for seasonal variation in
presentation of asthmatic episodes. In Mexico, Uruguay and
Chile (countries with well-defined seasons) 73 percent of
asthmatic patients showed no seasonality in the occurrences
of attacks.
The relationship of allergy and asthma was evaluated by an
attempt to correlate the diagnosis of asthma with the presence of other allergic diseases, and supplemented by objective diagnostic studies (Table 5). Positive intracutaneous and/
Table 5—Collaborative Study of Chronic AUergic Diseases
PAHO 1983: Complementary Studies for the Diagnosis of
Asthma
Direct
prick
Direct
Intracutan
Indirect
prick
Indirect
Intracutan
Radio
Immuno Assay
Blood
eosinoph
Secretion
eosinoph
Immunoglob
Nephelometric
assay
Total
Unknown
2
—
1
—
3
—
4
—
2
—
0
—
0
0
8
—
3
—
—
Not
done
26
(5.23)
191
(38.43)
491
(99.19)
486
(98.38)
477
(96.17)
95
(10.08)
225
(45.18)
437
(89.18)
491
(99.19)
3284
26
(5.23)
4
(0.81)
4
(0.81)
5
(1,01)
142
(28.51)
135
(27,11)
19
(3.98)
4
(0.81)
365
79
(15.93)
280
(56.34)
0
(0.00)
4
(0.81)
14
(2.82)
236
(47.39)
91
(18.27)
34
(6.94)
0
(0.00)
738
0
(0.00)
0
(0.00)
0
(0.00)
0
(0.00)
0
(0.00)
25
(5.02)
47
(9.44)
0
(0.00)
0
(0.00)
72
37
42
CONCLUSION
The prevalence of asthma in Latin American general
population surveys is quite variable. The difference of 0.4
percent in Peru and 4.3 percent in Brazil may be related to
differences in racial composition, environment, climate,
health facilities and methods of study. Sex differences favoring females over males in the older age groups are in
accordance with observations in other countries,
497
495
REFERENCES
Results Results Results
normal abnormal doubtful Total
391
(78.83)
34-36
Asthma in Latin America is most prevalent in childhood,
ranging from 2.7 percent in Chile to 7.5 percent in Uruguay.
Rates are higher for men than for women.
The clinical picture and etiologic factors differ in some
ways from those in reports published for the developed
countries and show a predominance of allergic background;
86 percent of patients were defined as atopic.
Asthmatic patients often have a history of other associated
allergic conditions (allergic rhinitis and atopic dermatitis).
This was observed in 46 percent of patients in a study
sponsored by the Pan American Health Organization.
Results of complementary examinations
(% of total)
Test
or prick tests were found in 359 cases for a cumulative
positive figure of 72 percent. Peripheral blood eosinophilia
was found in 47.4 percent of cases.
As a result of these clinical, functional and laboratory tests,
it was concluded that 86 percent of the patients studied had
an atopic background or had atopic asthma. This figure is
higher than those published for other parts of the world,
where the prevalence of extrinsic asthma varies from 44 to 83
percent depending upon the ages of those studied. No single
allergen was consistently positive in skin testing. However, a
number of publications from Latin America have stressed the
importance of house dust and the house dust mite, Dermatophagoides, as the most common provocative factors of
extrinsic asthma. '" The influence of industrial air pollution
could not be evaluated because 87 percent of surveyed
patients lived in urban residential areas; 4.52 percent in
industrial urban areas; 9.03 percent in suburban, nonindustrial areas, and 5.56 percent in rural areas.
The fact that Chile in its north-south extent includes
dramatic geographic and climatic contrasts offers an unusual
opportunity to look at possible relationships between these
factors and the presentation of variants of asthma. It was,
therefore, of interest to note that figures for prevalence and
the clinical characteristics and identifiable etiologic factors
did not differ greatly in the arid, temperate, rainy and cold
sections of the country.
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496
496
498
498
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42 Jimenez J. Gasto en salud y atencidn medica en cuatro regiones
de Chile en 1983. Corp6raci6n de Promocion Universitaria
(CPU), 1984
Prevalence Rates of Asthma in
Developing Countries and their
Comparison with those in Europe
and North America*
/. B. Cookson, M.D.
Prevalence rates for asthma in various parts of the world are
different and this cannot be entirely explained by differences in methodology. Low prevalence rates are found in
third world countries, particularly marked for children.
The reasons for these differences are obscure but are
largely environmental. Some suggestions are made herein
about their nature.
D
isease prevalence rates are a powerful, epidemiologic
tool and their use has led to a number of medical
success stories. These extend from John Snow and the Broad
Street pump and Jenner and cowpox, to the linking of
smoking with lung cancer; from asbestos exposure and
mesothelioma to the risk factors for coronary artery disease.
All these depended not just on isolated prevalence rates
but on comparisons between different populations. If variation between populations is real rather than due to the
method being used, this must mean that there is some difference between the countries. It may be inherent in the
population itself, perhaps genetic, or in the environment and
therefore susceptible to change, perhaps affording control of
the disease.
What populations should be studied? If they are widely
different, then the causes for variations within them are likely
to be multiple. If they are similar, prevalence rates are also
likely to be similar. It would seem reasonable to start with
widely different populations, then if prevalence rates are indeed different, to study more closely-related populations.
*From Glenfield General Hospital, Leicester, England.
CHEST / 91 / 6 / JUNE, 1987 / Supplement
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