Chapter 10 Flashcards
(22 cards)
What is the definition of a Cause?
An event, condition, or characteristic (or a combination of both) that plays an essential role in producing an occurrence of the health-related condition
Something that makes a difference to the outcome
What is a sufficient cause?
A factor (or more usually a combination of several factors) that will inevitably produce a disease
Like exposure - or something that if you have enough of will cause an outcome
Way to think of a Sufficient cause?
The boat scenario - How will the boat sink or stay a float?
Examples of sufficient causes of heart disease might include what?
HBP, smoking, high cholesterol. obesity, lack of physical activity (animals on boat)
While not 1 alone might increase heart disease, BUT COMBINATION of these can FORM sufficient cause
What is a component cause?
A factor that contributes towards disease causation but is not sufficient to cause disease on its own
How does component cause relate to the boat?
Think of rat, cat, fox and dog. Alone or even all together not enough to cause disease
What is a Necessary cause?
Any Factor (or component cause) that is required for the development of a given disease
How does necessary cause relate to the boat?
Think of the Tiger. You need the tiger in order to sink the boat (get the disease)
What is an example of a necessary cause?
HPV is Necessary for cervical cancer. You NEED HPV to get it.
How could we prevent the boat from sinking? (rat, cat, fox, dog, tiger)
We could change the outcome of the disease if we identified the dog and fox as component causes and now no matter what you can’t sink boat
Or identify the Necessary Cause (tiger) and also impossible
What is the two-step critical appraisal of a study we should do before we promote an exposure-disease relation as being casual
Step 1: Thorougly consider alternative non-causal explanations for an association (Type 1 error (increase sample size)(type two error- whats the power estimate).
Step 2: Judge the likelihood of causation using Hill’s criteria (7 of them)
What are the 7 criteria for Hill’s causation
Temporality, Strenght of Association, Consistency, Dose-Response Relationship (biological gradient), Biological plausibility, Coherence, Experimental data
What does temporality mean?
For a factor to cause a disease, it must occur before the disease develops. This is needed for causality. (Exposure exceeds the outcome)
Which study designs are causality?
Case-control, and intervention is temporal.
Are corss-sectional temporal studies?
Nope
What does strength of relationship mean?
A strong association between an exposure and a disease increases the likelihood of a causal relationship. However, the weaker associations may STILL be causal, but other evidence is needed.
What does consistency mean?
Repeated findings across different studies, populations, and settings lends support to a causal relationship. Inconsistent results may suggest that other factors are modifying the effect.
What does a dose-response relationship (Biological gradient) mean?
A dose-response relationship (where increased exposure leads to an increased risk of disease) strengthens the argument for causality.
What does biological plausibility mean?
The association should make biological snese, given the existing knowledge of biology, physiology, or pathophysiology.
What does Coherence mean?
The observed association should not seriously conflict with existing knowledge.
What is Coherence very similar to?
Biological plausibillity, could just merge the two
What does experimental data mean?
Experimental evidence (RCT or interventions) provides strong support for causation. however often hard to obtain (ethical or unpractical).
