Podcast
Questions and Answers
What is required for an association to indicate causality regarding exposure to a factor and the occurrence of disease?
What is required for an association to indicate causality regarding exposure to a factor and the occurrence of disease?
- Causality must be established through a single study.
- The association should be observed repeatedly across different studies. (correct)
- Specificity of the association must be proven in all cases.
- Exposure to the factor must occur after the disease manifestation.
Which of the following indicates that exposure to a factor precedes disease occurrence?
Which of the following indicates that exposure to a factor precedes disease occurrence?
- Temporal order of exposure and disease. (correct)
- Coherence with existing information.
- Frequency of the disease in varied populations.
- Specificity of the association.
Which of the following statements about specificity in causality is true?
Which of the following statements about specificity in causality is true?
- Lack of specificity dismisses any potential for causality.
- Specificity serves as strong evidence, but lack thereof is of less significance. (correct)
- Specificity is the sole requirement for establishing causality.
- Specificity must be confirmed in clinical trials to establish causation.
Which example illustrates coherence with biological plausibility?
Which example illustrates coherence with biological plausibility?
Which factor is least likely to support a causal relationship between exposure and disease?
Which factor is least likely to support a causal relationship between exposure and disease?
What is the primary distinction between an association and a causal relationship?
What is the primary distinction between an association and a causal relationship?
Which type of association is characterized by being a false connection due to chance or bias?
Which type of association is characterized by being a false connection due to chance or bias?
Which criterion for evaluating causal associations is based on the consistency of findings across different studies?
Which criterion for evaluating causal associations is based on the consistency of findings across different studies?
What does a relative risk ratio of greater than 4.0 indicate about an association?
What does a relative risk ratio of greater than 4.0 indicate about an association?
An indirect association typically occurs due to what underlying condition?
An indirect association typically occurs due to what underlying condition?
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Study Notes
Association and Causation
- Association refers to a statistical relationship between an exposure and a disease without confirming causation.
- Causation indicates a direct relationship where a risk factor leads to the development of a disease.
Statistical Significance
- Differences in disease occurrence between groups must first be analyzed for statistical significance.
- A statistically significant difference indicates a potential association between a factor and disease.
Types of Statistical Associations
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Artifactual (Spurious) Association:
- A false association arising from chance or bias in study methods.
- Requires replication to confirm. If not replicated, it may be deemed spurious.
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Indirect (Non-Causal) Association:
- Association exists only due to both being related to a common underlying condition.
- Altering the indirectly associated factor does not change disease frequency unless it affects the common condition.
- Example: Low altitude indirectly associated with cholera due to water pollution.
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Causal Association:
- Signifies a direct cause-effect relationship between a factor and disease.
Criteria for Causal Association
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Strength of Association:
- Measured by relative risk (risk ratio) or odds ratio.
- Ratios indicate strength:
- < 2.0: very weak
- 2.0 – 3.9: weak to moderate
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4.0: moderate to strong.
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Dose-Response Relationship:
- A direct correlation where increased exposure leads to higher disease incidence.
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Consistency of Association:
- Persistence of the association across multiple studies, populations, and methods strengthens causal inference.
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Temporality:
- Exposure to the risk factor must occur prior to the disease, allowing time for potential disease development.
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Specificity of Association:
- A specific association where one cause leads to one effect; for example, angiosarcoma linked to vinyl chloride exposure.
- Lack of specificity is less significant for establishing causality.
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Coherence with Existing Information (Biological Plausibility):
- Plausibility of the association in line with existing knowledge enhances causal argument.
- Example of plausibility: Higher disease incidence in sexually active individuals suggesting a sexually transmitted disease.
- Example of implausibility: A claim that the polio vaccine reduces fertility conflicts with established scientific understanding.
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