ASSESSMENT OF RISK AND BENEFIT IN EPIDEMIOLOGIC STUDIES

Question 1

• distinction between people who have and people who do not have exposure to the risk factor (or protective factor) under study.

Answer 1

Independent Variable

Question 2

• distinction between people who have and people who do not have the disease (or other outcome) under study.

Answer 2

Dependent Variable

Question 3

• difference between the frequency of disease in persons exposed to a risk factor and the frequency of disease in persons not exposed to the same risk factor.

Answer 3

Cohort Studies

Question 4

, from a defined population, we will not randomly assign a population. We need to know if a certain individual passed the exposure or was not exposed.

Answer 4

cohort study

Question 5

means a group of people being banded together or treated as a group.

Answer 5

Cohort

Question 6

focuses on the exposure. We will follow if the exposed people will develop the disease in the outcome.

Answer 6

Cohort

Question 7

• difference is between the frequency of the risk factor in case participants (persons with the disease) and the frequency of the risk factor in control participants (persons without the disease).

Answer 7

Case-Control Studies

Question 8

is defined as those who have the disease control those who do not have the disease.

Answer 8

Case-control

Question 9

start with people who have the disease, then looking back if the sick people were exposed with a certain risk factor.

Answer 9

Case-control

Question 10

Allow investigators to obtain absolute and relative measures of risk

Answer 10

Cohort studies

Question 11

Allow investigators to obtain only a relative measure of risk

Answer 11

CASE-CONTROL STUDIES

Question 12

MEASURES OF RISK FACTORS

Answer 12

1. Absolute Risk
2. Relative Risk
3. Odds Ratio (Relative Odds)
4. Attributable Risk

Question 13

2x2 table

Answer 13

Contingency table

Question 14

● Incidence of the disease

Answer 14

ABSOLUTE RISK (AbR)

Question 15

Indicate the magnitude of the risk in a group of people with a certain exposure

Answer 15

ABSOLUTE RISK (AbR)

Question 16

Only reflects a person’s overall risk of developing the health event

Answer 16

ABSOLUTE RISK (AbR)

Question 17

DISADVANTAGES

● It does not take into consideration the risk of disease in unexposed individuals

● It does not indicate whether the exposure is associated with an increased risk of the disease

Answer 17

ABSOLUTE RISK (AbR)

Question 18

Formula of ABSOLUTE RISK (incidence of the disease)

Answer 18

AbR = [a/(a+b)] x 100

Question 19

What formula to use: What is the absolute risk of lung cancer by smoking status?

Answer 19

AbR = a / (a+b) x 100

Question 20

Relative risk is also known as the

Answer 20

Risk Ratio (RR)

Question 21

The ratio of absolute risk (incidence rates) which can be used in cohort studies

Answer 21

RELATIVE RISK (RR)

Question 22

It determines whether there is an association between exposure to a risk factor and development of a disease

Answer 22

RELATIVE RISK (RR)

Question 23

Asks the question: How strong is the association?

Answer 23

RELATIVE RISK (RR)

Question 24

DISADVANTAGES

● Can only be used if your study is a cohort study

Answer 24

RELATIVE RISK (RR)

Question 25

RELATIVE RISK (RR) Formula

Answer 25

Relative risk = (incidence in exposed / incidence in unexposed)

Question 26

Formula: Incidence in exposed

Answer 26

a/(a+b)

Question 27

Formula: Incidence in unexposed

Answer 27

c/(c+d)

Question 28

ODDS RATIO (RELATIVE ODDS) is also known as

Answer 28

Relative Odds

Question 29

Can be used in case-control studies and cohort studies

Answer 29

ODDS RATIO (RELATIVE ODDS)

Question 30

Determines the proportion of cases who were exposed and the proportion of controls who were exposed

Answer 30

ODDS RATIO (RELATIVE ODDS)

Question 31

FORMULA for ODDS RATIO (RELATIVE ODDS)

Answer 31

Odds Ratio (OR) = Cross Products Ratio = (ad)/(bc)

Question 32

QUESTION RAISED WOULD BE: Is your exposure a risk factor associated with your development of the disease?

Answer 32

ODDS RATIO: COHORT STUDIES

Question 33

QUESTION RAISED WOULD BE: Is the exposure associated more with those who have the disease or to those who do not have the disease?

Answer 33

ODDS RATIO: CASE-CONTROL STUDIES

Question 34

Concordant pairs

Answer 34

EE and NN

Question 35

Disconcordant pairs

Answer 35

EN and NE

Question 36

= A way to control the confounding

Answer 36

Matching

Question 37

• Matching those controls to cases

Answer 37

MATCHED-PAIR CASE-CONTROL STUDY

Question 38

of cases = # of controls

Answer 38

MATCHED-PAIR CASE-CONTROL STUDY

Question 39

Helps us control for variables that may confound our results

Answer 39

MATCHED-PAIR CASE-CONTROL STUDY

Question 40

If we match out cases and controls on a separate variable, then we can see if there is a difference based just on the exposure

Answer 40

MATCHED-PAIR CASE-CONTROL STUDY

Question 41

Four potential outcomes: of MATCHED-PAIR CASE-CONTROL STUDY

Answer 41

1) Case exposed – control exposed (EE)
2) Case not exposed – control not exposed (NN)
3) Case exposed – control not exposed (EN)
4) Case not exposed – control exposed (NE)

Question 42

– EE and NN

▪ This means that they are in agreement (i.e., exposed-exposed, not exposed-not exposed

Answer 42

Concordant

Question 43

– EN and NE
▪ Not in agreement

Answer 43

Disconcordant (or discordant)

Question 44

In the case of a matched-pair case-control study, when calculating the odds ratio, we are looking at the __________ ONLY

Answer 44

discordant pairs

Question 45

The _______________ are ignored because they do not contribute to our knowledge of how cases and controls differ in regard to past history of exposure; also, we want to know the difference

Answer 45

concordant pairs (a & b)

Question 46

CALCULATING ODDS RATIO IF MATCHED-PAIR (Formula)

Answer 46

Odds ratio (matched pairs) = b/c

Question 47

ratio of the number of pairs that support the hypothesis of an association (pairs in which the case was exposed and the control was not) to the number of pairs that negate the hypothesis of an association (pairs in which the control was exposed and the case was not)

Answer 47

MATCHED PAIR ODDS RATIO

Question 48

No pairs

Cases and controls are individually counted

Answer 48

UNMATCHED PAIR ODDS RATIO

Question 49

Unmatched pairs odds ratio: formula

Answer 49

Unmatched pairs odds ratio = ad/bc

Question 50

• it regards something as being caused by something or someone OR being held responsible for or associated with

Answer 50

Attribute

Question 51

Measures the proportion of disease in the population (or just in the exposed group) that can be ‘attributed’ to the exposure

Answer 51

Attributable risk

Question 52

measure how much of the trait would be prevented were it removed from the population

Answer 52

Attributable risk

Question 53

useful in answering the question of how much disease can be prevented if we have an effective means of eliminating the exposure in question

Answer 53

Attributable risk

Question 54

How much of the disease that occurs can be attributed to a certain exposure?

Answer 54

Attributable risk

Question 55

______ and ______ are important measures of the strength of association, which is a critical consideration in deriving a causal inference

Answer 55

Relative risk (RR) and Odds ratio (OR)

Question 56

is a measure of how much of the disease risk is attributable to a certain exposure

Answer 56

Attributable risk (AR)

Question 57

is used to evaluate whether the exposure may be a cause of the outcome

Answer 57

Relative risk

Question 58

is the impact of the cause which leads to the outcome

Answer 58

Attributable risk

Question 59

is valuable in etiologic studies of disease o Example: help support the case for smoking as a cause of kidney transplant failure

Answer 59

Relative risk

Question 60

has major applications in clinical practice and public health o Example: describes the impact of smoking on the kidney transplant population

Answer 60

Attributable risk