wk 2 Flashcards
Determining the
cause of a disease.
Concept of Causality
A test that is given to
people who have no symptoms.
Screening Tests
Stages of Diseases:
*
Clinical
- Non-
clinical - Pre-clinical
- Sub-clinical
traditional epidemiology triangle
environment, host, agent time sa gitna
modern epidemiologic triangle
group of population, causative factor, risk factor. time as gitna
Every disease has its own pattern, usually
described by who is affected, where this takes
place, and when it takes place.
* This is typically called as
descriptive
epidemiology.
When looking at a particular disease, we often use
the term .
outcome
an outcome is the
dependent
variable.
The risk factors or exposures represent
independent variables.
The field of epidemiology deals with groups of
people at a time so “people” in epidemiological
studies are referred to as
study population.
generally implying the
geographical location.
place
There is an important concept in epidemiology
that refers to a geographical location where a
particular disease occurs frequently called
.
endemic
could also help identify an epidemic, or
a disease that occurs at a greater than expected
frequency.
time
There are two types of causes:
direct and indirect.
In , it is clear which factor caused the
problem without any intermediate steps.
direct causes
, the factor may cause the
problem but with an intermediate factor or step.
indirect causes
kohc’s criteris
The Microorganism or other pathogen must be
present in all cases of disease.
The pathogen can be isolated from the diseased
host and grown in pure culture
The pathogen from the pure culture should cause the
disease when inoculated into a healthy, susceptible
laboratory animal.
The pathogen must be reisolated from the new host and
shown to be the same as the originally inoculated
pathogen.
Credited with developing many
innovative and fundamental laboratory
techniques.
robert koch
His work was essential in proving the
germ theory of disease and establishing
that such diseases were contagious.
robert koch
Causality Based on Hill’s Aspects
- Temporal Relation
- Strength
- Dose-Response Relationship
- Consistency
- Plausibility
- Consideration of Alternate Explanations
- Experiment
- Specificity
- Coherence
Exposure (agent or risk factor)
always precedes the outcome
temporal relation
Defined by the size of the
association as measured by
appropriate statistical tests
strength
An increasing amount of
exposure increases the risk
dose-response relationship
The association is consistent when
results are repeated in studies in
different settings using different
methods.
Consistency
The findings agree with the
currently accepted understanding
of pathological processes.
Plausibility
In judging whether a reported finding is
causal, it is always necessary to
consider multiple hypotheses before
making conclusions about the causal
relationship between any two items
under investigation
Consideration of
Alternate Explanations
The condition can be altered by an
appropriate experimental regimen
Experiment
This established when a single
putative cause produces a specific
effect
Specificity
The association should be compatible
with existing theory and knowledge
Coherence
Avoids the initial occurrence of a
disease.
Primary Prevention
Limits the effect of a disease by
early detection and treatment
Secondary Prevention
Reduces the impact of a disease that
has already developed by preventing
complications.
Tertiary Prevention
Observed the effect of time, place, weather, and
diet on the spread of disease by comparing sick
persons to well persons.
james lind
His most notable scientific finding was how to
prevent scurvy on british ships. It was a debilitating
disease during his time.
james lind
His findings led to the practice of providing limes to
prevent this disease and to the nickname “Limey” for
british sailors. It is an example of primary prevention.
james lind
refers to the probability that the test correctly identifies a
person as having a disease when the person does have the disease.
Sensitivity
refers to the probability that a test correctly identifies the
person as not having a disease when the person actually does not have
the disease.
Specificity
The proportion of people who test
positive for a disease who actually have the disease.
Positive Predictive Value (PPV)
- The proportion of people who test
negative for a disease who actually do not have the disease.
Negative Predictive Value (NPV)
was an English epidemiologist and statistician who
pioneered the randomized clinical trial and,
together with Richard Doll, was the first to
demonstrate the connection between cigarette
smoking and lung cancer in 1950.
sir austin bradford hill
Hill also suggested that researchers should
randomize clinical trials to evaluate the effects of a
drug or treatment by monitoring large groups of
people
sir austin bradford hill
style of research based conclusions off of unmistakable events such as
death, used unbiased judges with no stake in the research when evaluating
subjective measurements, and masked which patient received a particular
treatment from doctors and patients alike.
sir austin bradford hill
the total number of. individuals who have an
attribute or disease at a particular time (or period)
disease occurrence
can be broadly applied to any
factor that may be associated with an outcome of interest.
exposure
In order for individuals to develop a disease, they must be both
to the disease and to the disease.
exposed and suscpetible
person in the population or study group identified
as having the particular disease,health disorder or condition
under investigation
case
In epidemiology is often synonymous with disease outcome of
interest
case
very specific to a particular surveillance effort or
study
case
