Association, Casual inference & causality

Question 1

Cause

Answer 1

An precurser event/condition/characteristic requrired for the occurrence of the diesase

Question 2

Associations

Answer 2

Does the exposure cause the disease? Associations are relationships btw an exposure and an outcome

Question 3

3 types of associations

Answer 3

artifactual, non causal, causal

Question 4

artifactual association

Answer 4

can arise from significant bias or extensive confounding

Question 5

non causal associations

Answer 5

can occur in 2 ways

1. the disease may cause the exposure
2. the diesase and the exposure are both associated with a third factor

Question 6

Koch’s postulate’s(for infectious disease)

Answer 6

4 keys for implicating a causational relationship

1. must be present in every case of disease
2. must not be found in cases of other disease or healthy individuals
3. must be capable of isolation, culture and reproducing disease in experimental animals
4. must be recovered from experimentally induced diseased animasl

Question 7

Koch’s postulate’s limitations

Answer 7

disease production may require presence of co-factors that postulates don’t address
viruses can’t be cultured similar to bacteria
not all viruses bacteria induce clinical diesease

Question 8

Mill’s Canons

Answer 8

the cuase of any effect must consist of a constellation of components that act in concert

Question 9

Sufficient cause

Answer 9

a set of minimal conditions/ events that inevitably produce disease. a cuase which preceds a disease, and if present, the diesase will ALWAYS occur

Quite rare apart from genetic abnormailites… homozygous recessive diesase

Question 10

Component causes

Answer 10

sufficent cause have multipble required components…. a characterisitc that if present and active, increases the probablity of a particular disease …. some patients must be primed or suseptible to disease before component cuases induce disease….

Question 11

Necessary Cause

Answer 11

a cause which precedes a disease and has the following relationship with it…. cause must be present for the disease to occur, yet the cuase may also be present without the disease occuring… TB

Question 12

Component cause

Answer 12

in order to examine the influence of a single factor, it is necessary to adjust or control for the effects of the other factors… mathematically or mthodoligically

Question 13

ways to control for multipple causations

Answer 13

restrictions, matching, stratification

Question 14

Restricting

Answer 14

keep out the other factors from the study

Question 15

matching

Answer 15

similar characteristics in each group

Question 16

stratification

Answer 16

categorize patients on exposure levels or disease severity or other imporatnat patient characteristics

Question 17

Causal inference process

Answer 17

inductively oriented criteria…. hill’s guidlines. derived foloowing us surgeon generals 1964 report on smoking…. IN what circumstances cna we pass from this observed association to a verdict of causation?

Question 18

Hill’s Criteria… an interpretive application process

Answer 18

1. strength
2. consitency… specificity
3. temporality
4. biologic gradient
5. plausibility… coherence, experiment, anaology
   The higher the number of criteria met, when evaluating an association, the more likely it may be causal

Question 19

Strenght

Answer 19

Referes to the size of the association. THe greater the associations, the more convincing it MIGHT actually be causal…
A strong association is neither necessary nor sufficient for causality and weakness of an association is neither necessary nor sufficient for absence of causality.

Question 20

Consistency

Answer 20

reproducibility… the repeated observation of association in different populations under different circumstaneces in different studies, not just once…. consitency may still obscure the truth…

Question 21

Temporality

Answer 21

is the necessity that the cause PRECEDE the effect/outcome in the time

Question 22

Proximate cause

Answer 22

short term interval

Question 23

distant cause

Answer 23

long term interval

Question 24

induction period

Answer 24

component cause to diesase onset

Question 25

latent period

Answer 25

disease onset to diagnosis

Question 26

Biological gradient

Answer 26

refers to the observation of a gradient of risk (dose-response) associated with the degree of exposure…. some things have a threshhold effect, no effect until a certain level of expsoure is reached

Question 27

Plausibility(biologically)

Answer 27

refers to the biological feasibility (understanding) the associated can be understood and explained (biologically/physiologically/medically)….. It has to be able to be proven that that can occur in the body for that reason….

Question 28

Pitfalls in causal research

Answer 28

bias- confounding- effect modifications…..

Question 29

pitfall synergism

Answer 29

the interaction of 2 or more presumably -causal variables so that the combined effect is clearly greater than the sum of the individual effects