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Epidemiology Basics
What is epidemiology?
Epidemiology
refers to applying the tools of public health to the population, rather
than looking at specific individuals as clinical medicine does. The
purpose of epidemiology is to look at the distribution and determinants
of diseases and other health problems in the population. This is
somewhat different from the focus of the clinician who's looking for
signs and symptoms of disease or making diagnoses, but doing it in
specific individuals rather than within the population.
What is the basic premise of epidemiology?
The basic premise
of epidemiology is that health problems and health issues can be
defined according to major characteristic variables, and these are
known as person, time, and place variables. For example, many disease
entities vary according to geographic location. There are some diseases
that we have in some parts of the world, for example, the tropical
areas of the world, that we don't have in the United States, that are
located in temperate areas. Disease conditions and health problems tend
to vary according to racial and ethnic breakdown as well. For example,
non-Hispanic white people have certain characteristic forms of
morbidity and mortality. And these may not be the same, or expressed to
the same extent in other racial groups such as Hispanic whites, African
Americans, Asians, or other groups. Another aspect we look at in
epidemiology is the variable of time. Health conditions and diseases
tend to vary over time. For example, there are seasonal variations in
many infectious diseases, an example being influenza. There are long
term time trends in diseases. Recently, coronary heart disease has
tended to level off or decline. And then, that is being replaced by
cancer, which is a fast growing cause of mortality in the United States.
What are the two branches of epidemiology?
One of them is
called descriptive epidemiology, and then another one is known as
analytic epidemiology. Descriptive epidemiology aims to describe a
health condition within the population. For example, how does it vary
according to age group, or by geographic location, or by other person
variables. Also, place variables and time variables. The purpose of
descriptive epidemiology is to try to devise hypotheses about the
nature, or ideology, of a disease. For example, if we observe a problem
that is relevant to many geographic areas. If we observe in Los Angeles
that areas of Los Angeles that have high amounts of traffic have high
rates of cancer, then we can already begin to think of some hypotheses
about what may be going on, and then conduct further studies to
investigate what is happening. In contrast with descriptive
epidemiology is analytic epidemiology, which tries to uncover the
causes of diseases in populations. There are certain types of study
designs that are used in analytic epidemiology. For example, case
control studies, cohort studies, and experimental studies. The purpose
of this is to take hypotheses that have been identified and then
investigate them with respect to ideology, and then try to track down a
cause of the disease, such as if it's a chronic disease or an
infectious disease, or food borne illness, or whatever.
What are the most common uses of epidemiology?
There are
seven identified uses of epidemiology. One of them is to study the
history of the health of the population. For example, the types of
problems that affect society and humanity have changed over periods of
time. If you look at data for the 1900s, you would see that there were
certain infectious diseases that predominated at that time. If you
compare those with the patterns that we have at present, you would see
that many of the infectious diseases have been replaced by chronic
diseases of long duration, of long standing. Another use of
epidemiology is for diagnosis of the health of the community. In this
type of epidemiology, we try to make a picture of the characteristics
of the community with respect to its demographic makeup, in terms of
particular health problems that exist in the community. From that
information we can propose specific plans and programs to intervene in
order to optimize the health of the community. Another use is known as
studying the working of health services, and this use is sometimes
referred to as Operations Research. For example, we want to find out if
there are areas of the community or our city or county, our state or
whatever geographic subdivision we're looking at, that are lacking in
health services or whether there are some that are overlapping. That is
also known as Operations Research. Another use of epidemiology is
called the study of individual risks. For example, one may have
observed the prognosis of cancer patients who are diagnosed with a
specific form of cancer, or cancer patients who undergo a certain type
of treatment. What is their prognosis over time? How long are they
likely to live? The use of epidemiology known as identifying syndromes
has to do with identifying characteristic patterns of symptoms and
other dimensions that are associated with a specific disease. As an
example, the common cold has certain symptoms associated with it or the
flu - runny nose, headaches, muscle aches, fever and so forth. This is
another use of epidemiology. Completing the clinical picture is still
another use of epidemiology, and that has to do with the full
manifestations of a disease. Often, clinicians who come into first
contact with the disease are only aware of the most acute or dramatic
cases of the disease. In reality, there may be other types or other
manifestations of the disease. Epidemiology enables us to find out what
those are, and the final use of epidemiology is known as the search for
causes. An example of this type of use of epidemiology would be to find
out what causes chronic diseases such as cancer or heart disease. What
causes common infectious diseases that we know about. Sometimes
epidemiologists have very little knowledge about the disease when they
begin, and as a result of their investigations they're able to more
fully uncover the causes for the disease.
What are the main components of epidemiology?
The components
of epidemiology include the following: disease determinants - which are
the cause or factors, the distribution, and morbidity or mortality.
Distribution refers to how the disease occurs in the population,
morbidity refers to sickness, and mortality refers to death.
Why is epidemiology considered an interdisciplinary field?
Epidemiology
is called an interdisciplinary field meaning that it draws on many
different disciplines. An example being statistics and biostatistics,
microbiology, toxicology, clinical medicine, even psychology and the
behavioral sciences. Epidemiology aims to use the appropriate tools
that may exist to investigate and study diseases and disease outbreaks.
What are the scientific foundations of epidemiology?
The
specific foundations is discipline that draws on the best things from a
lot of different fields. For example, my own background was in
psychology. Epidemiology is interested in the psychosocial aspect of
disease and process these relating to disease. Demography is certainly
important in the description of the population. Microbiology is an
aspect of epidemiology. Biostatistics is certainly at the core of
epidemiology and is very much a central aspect of epidemiology.
Molecular and genetic techniques are now becoming more prominent. In
some, epidemiology varies from a large number of disciplines and uses
the best tools that it can.
What are the most common methods epidemiologists use to study disease?
One
of the common methods that epidemiology uses to study disease is called
quantification. Quantification involves translating qualitative
information or qualitative impressions into numbers that can be
measured. And then, in addition, epidemiology uses a special
vocabulary. Some examples of the special vocabulary are morbidity,
mortality, incidence, prevalence, rate, risk, and so forth. All of
these terms, and vocabulary terms, are characteristic to the discipline
of epidemiology.
How does epidemiology approach the study of diseases within a population?
Epidemiology
uses an interdisciplinary approach to study the occurrence of diseases
in populations. For example, the work of biostatisticians is important
in quantifying and measuring the occurrence of disease. The skills of
microbiologists are helpful to identify and track down agents of
disease. The contributions of demography are certainly important -
sociology, psychology and many other disciplines.
What are the most common variables used to evaluate my community's health?
Examples
of common demographic variables are the age distribution of the
population, the racial and ethnic distribution, socioeconomic status,
education, and lifestyle characteristics. Social characteristics relate
to social instability, the social support level, affluence,
availability of health care facilities and related variables.
Do clinical descriptions of disease differ from epidemiological descriptions of disease?
The
clinical description of a disease is quite different from an
epidemiologic description. A clinical description involves the use of
specific signs and symptoms of a disease. For example, what you might
see on your clinical record, such as what your temperature was, or what
your height is, or your weight. Essentially, it looks at what your
symptoms are. In an epidemiologic description of a disease, we're
interested in describing the populations among which the disease is
more common, the subsets of the population where it occurs, how it
varies by age, gender and other demographic variables.
Which sources of data do epidemiologists draw upon?
Epidemiologists
draw from a wide number of data sources, and I can name several
examples. For example, one of the most important ones is vital
statstics data. This includes data from birth records, death records,
surveillance systems mantained by local government that are forwarded
to the state level, to the Centers for Disease Control and Prevention.
There are data registries that collect data on specific diseases such
as cancer, and then there are national and local surveys that are
conducted such as the Health Interview Survey and the Health
Examination Survey. An example of a local survey conducted in
California is the CHIS, or California Health Interview Survey.
What is epidemiology?
Epidemiology
refers to applying the tools of public health to the population, rather
than looking at specific individuals as clinical medicine does. The
purpose of epidemiology is to look at the distribution and determinants
of diseases and other health problems in the population. This is
somewhat different from the focus of the clinician who's looking for
signs and symptoms of disease or making diagnoses, but doing it in
specific individuals rather than within the population.
What is the basic premise of epidemiology?
The basic premise
of epidemiology is that health problems and health issues can be
defined according to major characteristic variables, and these are
known as person, time, and place variables. For example, many disease
entities vary according to geographic location. There are some diseases
that we have in some parts of the world, for example, the tropical
areas of the world, that we don't have in the United States, that are
located in temperate areas. Disease conditions and health problems tend
to vary according to racial and ethnic breakdown as well. For example,
non-Hispanic white people have certain characteristic forms of
morbidity and mortality. And these may not be the same, or expressed to
the same extent in other racial groups such as Hispanic whites, African
Americans, Asians, or other groups. Another aspect we look at in
epidemiology is the variable of time. Health conditions and diseases
tend to vary over time. For example, there are seasonal variations in
many infectious diseases, an example being influenza. There are long
term time trends in diseases. Recently, coronary heart disease has
tended to level off or decline. And then, that is being replaced by
cancer, which is a fast growing cause of mortality in the United States.
What are the two branches of epidemiology?
One of them is
called descriptive epidemiology, and then another one is known as
analytic epidemiology. Descriptive epidemiology aims to describe a
health condition within the population. For example, how does it vary
according to age group, or by geographic location, or by other person
variables. Also, place variables and time variables. The purpose of
descriptive epidemiology is to try to devise hypotheses about the
nature, or ideology, of a disease. For example, if we observe a problem
that is relevant to many geographic areas. If we observe in Los Angeles
that areas of Los Angeles that have high amounts of traffic have high
rates of cancer, then we can already begin to think of some hypotheses
about what may be going on, and then conduct further studies to
investigate what is happening. In contrast with descriptive
epidemiology is analytic epidemiology, which tries to uncover the
causes of diseases in populations. There are certain types of study
designs that are used in analytic epidemiology. For example, case
control studies, cohort studies, and experimental studies. The purpose
of this is to take hypotheses that have been identified and then
investigate them with respect to ideology, and then try to track down a
cause of the disease, such as if it's a chronic disease or an
infectious disease, or food borne illness, or whatever.
What are the most common uses of epidemiology?
There are
seven identified uses of epidemiology. One of them is to study the
history of the health of the population. For example, the types of
problems that affect society and humanity have changed over periods of
time. If you look at data for the 1900s, you would see that there were
certain infectious diseases that predominated at that time. If you
compare those with the patterns that we have at present, you would see
that many of the infectious diseases have been replaced by chronic
diseases of long duration, of long standing. Another use of
epidemiology is for diagnosis of the health of the community. In this
type of epidemiology, we try to make a picture of the characteristics
of the community with respect to its demographic makeup, in terms of
particular health problems that exist in the community. From that
information we can propose specific plans and programs to intervene in
order to optimize the health of the community. Another use is known as
studying the working of health services, and this use is sometimes
referred to as Operations Research. For example, we want to find out if
there are areas of the community or our city or county, our state or
whatever geographic subdivision we're looking at, that are lacking in
health services or whether there are some that are overlapping. That is
also known as Operations Research. Another use of epidemiology is
called the study of individual risks. For example, one may have
observed the prognosis of cancer patients who are diagnosed with a
specific form of cancer, or cancer patients who undergo a certain type
of treatment. What is their prognosis over time? How long are they
likely to live? The use of epidemiology known as identifying syndromes
has to do with identifying characteristic patterns of symptoms and
other dimensions that are associated with a specific disease. As an
example, the common cold has certain symptoms associated with it or the
flu - runny nose, headaches, muscle aches, fever and so forth. This is
another use of epidemiology. Completing the clinical picture is still
another use of epidemiology, and that has to do with the full
manifestations of a disease. Often, clinicians who come into first
contact with the disease are only aware of the most acute or dramatic
cases of the disease. In reality, there may be other types or other
manifestations of the disease. Epidemiology enables us to find out what
those are, and the final use of epidemiology is known as the search for
causes. An example of this type of use of epidemiology would be to find
out what causes chronic diseases such as cancer or heart disease. What
causes common infectious diseases that we know about. Sometimes
epidemiologists have very little knowledge about the disease when they
begin, and as a result of their investigations they're able to more
fully uncover the causes for the disease.
What are the main components of epidemiology?
The components
of epidemiology include the following: disease determinants - which are
the cause or factors, the distribution, and morbidity or mortality.
Distribution refers to how the disease occurs in the population,
morbidity refers to sickness, and mortality refers to death.
Why is epidemiology considered an interdisciplinary field?
Epidemiology
is called an interdisciplinary field meaning that it draws on many
different disciplines. An example being statistics and biostatistics,
microbiology, toxicology, clinical medicine, even psychology and the
behavioral sciences. Epidemiology aims to use the appropriate tools
that may exist to investigate and study diseases and disease outbreaks.
What are the scientific foundations of epidemiology?
The
specific foundations is discipline that draws on the best things from a
lot of different fields. For example, my own background was in
psychology. Epidemiology is interested in the psychosocial aspect of
disease and process these relating to disease. Demography is certainly
important in the description of the population. Microbiology is an
aspect of epidemiology. Biostatistics is certainly at the core of
epidemiology and is very much a central aspect of epidemiology.
Molecular and genetic techniques are now becoming more prominent. In
some, epidemiology varies from a large number of disciplines and uses
the best tools that it can.
What are the most common methods epidemiologists use to study disease?
One
of the common methods that epidemiology uses to study disease is called
quantification. Quantification involves translating qualitative
information or qualitative impressions into numbers that can be
measured. And then, in addition, epidemiology uses a special
vocabulary. Some examples of the special vocabulary are morbidity,
mortality, incidence, prevalence, rate, risk, and so forth. All of
these terms, and vocabulary terms, are characteristic to the discipline
of epidemiology.
How does epidemiology approach the study of diseases within a population?
Epidemiology
uses an interdisciplinary approach to study the occurrence of diseases
in populations. For example, the work of biostatisticians is important
in quantifying and measuring the occurrence of disease. The skills of
microbiologists are helpful to identify and track down agents of
disease. The contributions of demography are certainly important -
sociology, psychology and many other disciplines.
What are the most common variables used to evaluate my community's health?
Examples
of common demographic variables are the age distribution of the
population, the racial and ethnic distribution, socioeconomic status,
education, and lifestyle characteristics. Social characteristics relate
to social instability, the social support level, affluence,
availability of health care facilities and related variables.
Do clinical descriptions of disease differ from epidemiological descriptions of disease?
The
clinical description of a disease is quite different from an
epidemiologic description. A clinical description involves the use of
specific signs and symptoms of a disease. For example, what you might
see on your clinical record, such as what your temperature was, or what
your height is, or your weight. Essentially, it looks at what your
symptoms are. In an epidemiologic description of a disease, we're
interested in describing the populations among which the disease is
more common, the subsets of the population where it occurs, how it
varies by age, gender and other demographic variables.
Which sources of data do epidemiologists draw upon?
Epidemiologists
draw from a wide number of data sources, and I can name several
examples. For example, one of the most important ones is vital
statstics data. This includes data from birth records, death records,
surveillance systems mantained by local government that are forwarded
to the state level, to the Centers for Disease Control and Prevention.
There are data registries that collect data on specific diseases such
as cancer, and then there are national and local surveys that are
conducted such as the Health Interview Survey and the Health
Examination Survey. An example of a local survey conducted in
California is the CHIS, or California Health Interview Survey.
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