Fnm 041 Epidemiology - Cohort Studies

Front 1

Relative risk =

Back 1

Incidence (or mortality) rate in those exposed to a risk factor
/
Incidence (or mortality) rate in those not exposed to a risk factor

Front 2

Incidence (or mortality) rate in those exposed to a risk factor
/
Incidence (or mortality) rate in those not exposed to a risk factor

=

Back 2

Relative risk

Front 3

The fact that assessment of risk factor exposure is made before the disease develops is an advantage of a longitudinal study T/F

Back 3

T

Front 4

The fact that incidence rates can be calculated among the 'exposed' and 'non-exposed' and the relative risk can be estimated directly is an advantage of longitudinal/cohort studies T/F

Back 4

T

Front 5

The fact that longitudinal observation provides a more accurate picture of the natural history of a disease is an advantage of longitudinal/cohort sudies T/F

Back 5

T

Front 6

What are the disadvantages of longitudinal/cohort studies?

Back 6

Expensive to run

Loss to follow up may produce bias

Subjects may vary their risk factor exposure (e.g. giving up smoking)

May be problems maintaining the standardisation of techniques

This typ eof study is not suited to studying rare diseases which would require a large and costly cohort

Front 7

What are the two types of error?

Back 7

Random and systematic

Front 8

This type of bias occurs when there is a systematic difference between the characteristics of the people selected for a study, and the characteristics of those who are not

Back 8

Selection bias

Front 9

This type of bias occurs when there is a differential recall of information by cases and controls

Back 9

Recall bias

Front 10

___________ can occur when another exposure exists in the study population and is associated both with the disease and the exposure being studied

Back 10

Confounding

Front 11

___________ occurs when the effects of two exposures (risk factors) have not been separated, and it is therefore incorrectly concluded that the effect is due to one, rather than the other variable

Back 11

Confounding

Front 12

For a variable to be a confounder, it must be a determinant of the occurance of the disease (i.e. a risk factor) and be associated with the exposure under infestigation T/F

Back 12

T

Front 13

Matching controls to cases helps control confounding T/F

Back 13

T

Front 14

Stratification (separate analysis by level of confounding) helps control confounding T/F

Back 14

T

Front 15

'Separate analysis by level of confounding'

Back 15

Stratification (e.g. measuring smokers and non-smokers separately)

Front 16

Multivariate analysis produces adjusted relative risk estimates helps reduce confounding T/F

Back 16

T

Front 17

If a characteristic predicts the development of disease, it is said to be a...

Back 17

Risk factor

Front 18

The incidence rate of disease (or other outcome) in any defined population

Back 18

Absolute risk

Front 19

Absolute risk is not useful in isolation as it doesn't compare incidence in the exposed group compared with the unexposed group T/F

Back 19

T

Front 20

The incidence rate in the exposed group minus the incidence rate in the unexposed group

Back 20

Absolute risk reduction/attributable risk/excess risk

Front 21

This represents the risk attributable to the risk factor being investigated

Gives an idea of how much a disease is due to a particular risk factor

Back 21

Absolute risk reduction/attributal risk/excess risk

Front 22

The ratio of incidence rate in the exposed group to that in the unexposed group

Back 22

Relative risk

Front 23

Relative risk does compare incidence rates in exposed and unexposed groups T/F

Back 23

T

Front 24

How do you measure relative risk in a cohort study/randomised control trial?

Back 24

Incidence (Exposed)/Incidence (unexposed)

Front 25

(Absolute risk in exposed - absolute risk unexposed)
/
Absolute risk unexposed

=

Back 25

Relative Risk Reduction (RRR)

Front 26

Relative Risk Reduction (RRR) =

Back 26

(Absolute risk in exposed - absolute risk unexposed)
/
Absolute risk unexposed

Front 27

What is causal inference?


Look at the words

Back 27

The process of determining whether observed associations are likely to be causal

Bradford Hill criteria

Front 28

The higher the relative risk, the more likely it is that the association is causal T/F

Back 28

T


*Understand* this - RR compares incidence rates in exposed and unexposed groups

Front 29

Temporal sequence of cause and effect is an absolute criterion for causality

Back 29

Did the exposure occur before the disease?