Association to Causation Flashcards
To memorize and study all about causation
If we determined that an exposure is associated with a disease, the next question is _________________
whether the observed association reflects a causal relationship
In terms of disease etiology, in the case of animal studies and in vitro systems, the results may not be applicable to humans due to ____________________ and different environmental influences across species
genomic difference
True or False: Exposing humans to certain exposure is ethical
False, not ethical
As exposing humans to certain exposure is not ethical what is the best alternative?
Make observations in human populations by:
1. Unplanned or natural experiments
2. Observed populations predisposed to disease due to certain hazards
What are the etiological hazards for studying disease etiology?
- Occupational
- Environmental
- Genetic
What is the frequent sequence of studies in human populations? List them in order
- Clinical observations
- Available data
- Case-control studies
- Cohort studies
- randomized Trials
It is a part of studying disease etiology where its main goal is to review medical records and see if similar exposures are reported in other patients
Available Data
Perform association studies. The quicker way to do that is to document past
exposure in diagnosed patients through a case-control study. Cohort studies may be done next to see if initially healthy individuals with the exposure develop the disease.
Case-control studies and Cohort Studies
What is the quicker way to perform association studies?
Document past exposure in diagnosed patients through case-control studies.
What is done next to a case-control study?
Cohort study
It is ideal for beneficial or protective-against-disease exposures.
Randomized Control Trials (RCTs)
Part of studying disease etiology was not done to test potentially harmful exposures
Randomized Trials
In interpreting Associations we include the following:
- Case-control studies
- Cohort Studies
What are the types of associations?
(1) Causal and (2) Due to Confounding
True or False: Not knowing if an association is due to a causal relationship or not is important
False, Knowing
If __________________ or ______________ preventive measures will not work
Causal or Due to confounder
If cause, or there is a preventive measure against the identified exposure, disease incidence _____________
decrease
It is also called as waste of resources in terms of interpreting associations
no/minimal change in incidence
In direct causes of disease, what does it involve?
Factor, Disease
In Indirect cause of disease, it includes:
Factor, Step 1, Step 2, Disease
Necessary (-) factor disease _______ develops
Never
In Sufficient (+) factor disease __________ develops
Always
Give the process or diagram of Necessary and Sufficient
Factor A ——-> Disease
Necessary not Sufficient
Factor A
+
Factor B————–> Disease
+
Factor C
Sufficient, not necessary
Factor A————–> Disease
or
Factor B————–> Disease
or
Factor C—————>Disease
Not sufficient, not necessary
Factor A + Factor B ——> Disease
or
Factor C + Factor D ——> Disease
or
Factor E + Factor F ——-> Disease
What are the evidence for a causal relationship? Give all.
- Temporal relationship
- Strength of the Association
- Dose-response relationship
- Replication of the findings
- Biologic plausibility
- Consideration of alternate explanations
- Cessation of exposure
- Consistency with other knowledge
- Specificity of the association
It is evidence for a causal relationship, where If a factor is believed to be the cause
of a disease, exposure to it must
occur before the disease develops
Temporal Relationship
Temporal Relationship exemplified by __________ studies
Cohort
True or False: The length of interval between exposure and disease is deemed optional
False, exposure and disease is important
The stronger the association, the more likely it is that the relation is ___________.
Causal
The stronger the association, the more likely it is that the relation is causal.
Strength of the Association
As the dose of exposure increase, risk of disease____________
increases
It refers to the dose of exposure and risk of disease and no disease may develop up to a certain level of exposure above this level, and disease may develop
Dose-Response Relationship
If an association is observed, we would also expect it to be seen ______________ within subgroups of the population and in different
populations, unless there is a clear reason to expect different results.
consistently
If an association is observed, we would also expect it to be seen consistently within subgroups of the population and in different
populations, unless there is a clear reason to expect different results.
Replication (of the findings)
It refers to the coherence with the current body of biologic knowledg
Biologic Plausibility
Evidence for a causal relationship, where all other explanations (other possible causes) have been investigated and
ruled out.
Consideration of Alternate Explanations (Confounding)
Evidence for a causal relationship, if a factor is a cause of a disease
Cessation of Exposure
In Cessation of Exposure as the risk of the disease decreases elimination of exposure __________
decreases
Evidence for a causal relationship, if a relationship is causal, we would expect the findings to be consistent
with other data.
Consistency with other knowledge
Evidence for a causal relationship, where it is identified to be the weakest basis for causality (disease occurrence à multi-factorial)
Specificity of the Association
An association is specific when a certain exposure is associated with only one disease.
Specificity of the Association
True or False: Any observational study will be perfect
False, never be perfect
In observational study there can still be ________________ in the results drawn from the collected and analyzed data
Credibility
In observation studies, these are need to be taken into account:
- biases
- Confounders
- Interactions
- Role of chance
it refers to any systematic error in the design, conduct or analysis of a study that results in a mistaken estimate of an exposure’s effect on the risk of disease.
Bias
Selection Bias occurs where there is a ____________ _______________ between the people who are included in a study and those who are not, or when study and
comparison groups are selected inappropriately or using different criteria.
systematic difference
Occurs when there is a systematic difference between the
people who are included in a study and those who are not, or when study and comparison groups are selected inappropriately or using different criteria.
Selection Bias
Selection Bias may result from:
- Disinterest among diseased or exposed individuals to join (vs volunteers)
- Low response rates
- Data collection is done through convenient channels (email, chat, via supervisor, etc)
- Participant loss to follow-up
Selection bias affects the _______________ and _______________________ regarding the association of exposure and
outcome.
internal validity
legitimacy of inference
Control of selection bias / Assessment of the effect of bias
- Use of clearly defined eligibility criteria
- Ensure high participation rates in all study groups
- Use external comparison
- Conduct sensitivity analysis
It happens when information on the exposure and disease outcome are incorrect or à Misclassification Bias
Information Bias
Information bias may result from:
- Limited sensitivity and specificity of diagnostic tests
- Wrong encoding of an individual’s disease outcome and/or exposure status (Interviewer
bias) - Enhanced recall among cases compared to control (Recall Bias)
- Reluctance to report an exposure due to attitude, belief, and/or perception (Reporting
bias)
It is the measurement error and resulting misclassification occurs to a greater extent in one group than another
Differential misclassification
HIV Cases and Sexual Exposure are stigmatized topics is an example of what type of effect?
underestimation of the effect
Recall bias: Women who had a baby with a malformation tend to remember (or report)
more mild infections that occurred during their pregnancies than mothers of infants
without malformations. What effect does the situation above show?
overestimation of the effect
It is when measurement error and any resulting misclassification occur equally among comparison groups
(affects everyone in the study)
Non-differential misclassification
Give ways on how to address misclassification bias
- Clearly define everything that is to be measured
- Ensure that the same instruments and methods are used in all study
groups. - Instruments or tests need to be standardized.
- Conduct validation (for accuracy, use of a gold standard) and repeatability (for
precision) studies.
Two types of measurement errors are?
Survey
Analytic Study
What are the two types of Surveys?
Random and Systematic
What are the two types of Analytic Study?
- Non-differential (same in all groups)
- Differential (different in different groups)
In a Random study, what is the consequence or outcome?
There is no Bias in the mean but a lack of Precision
In terms of the systematics survey, what is the consequence of the measurement error?
Biased Results
Non-differential and Differential analytic studies are either ___________ or ___________.
Random or Scientific
Non-differential random or systematic could be ______________
Bias to Null
Differential in Random or Systematic could be __________________________
Bias towards or away from the null.
