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Phase 3a > Public Health - Epidemiology > Flashcards

Public Health - Epidemiology Flashcards

1
Q

Study design

What is the direction of a cohort study?

A

Prospective (exposure –> outcome)

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2
Q

Study design

What is the direction of a case control study?

A

Retrospective (outcome –> exposure)

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3
Q

Study design

What is the direction of a cross-sectional study?

A

There is no direction, it measures prevalence at a point in time

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4
Q

Study design

What is the direction of a randomised control trial?

A

Prospective (exposure –> outcome)

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5
Q

Definition

What is the definition of incidence?

A

The number of individuals who develop a specific disease or experience a specific health problem during a particular time period

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6
Q

Definition

What is the definition of prevalence?

A

The total number of individuals who have a specific disease at a specific point in time

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7
Q

Definition

What is person-time?

A

The measure of time at risk

Time from entry to a study to either:
- disease onset
- loss to follow up
- end of study

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8
Q

Formula

How do you calculate incidence rate?

A

Incidence rate = (number of people who have become cases in a given time period) / (total person-time at risk during that period)

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9
Q

Formula

How is cumulative incidence calculated?

A

Cumulative incidence = (number of people who have become cases in a given time period) / (number of disease-free people at the start of the study)

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10
Q

Definition

What is absolute risk?

A

The risk of developing a disease over a time period, it has units

An example would be 50 deaths/1000 population

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11
Q

Formula

How is relative risk/risk ratio calculated?

A

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

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12
Q

Definition

What is relative risk/risk ratio?

A

Compares the risk of a health event among one group with the risk among another group (e.g., exposed vs unexposed), it has no units

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13
Q

Definition

What is attributable risk?

A

The rate of disease in the exposed that may be attributed to the exposure.
It is a type of absolute risk (absolute excess risk).

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14
Q

Formula

How is attributable risk calculated?

A

Attributable risk = (incidence in the exposed) - (incidence in the unexposed)

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15
Q

Formula

How is absolute risk reduction calculated?

A

Absolute risk reduction = (cumulative incidence/absolute risk in unexposed) - (cumulative incidence/absolute risk in exposed)

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16
Q

Formula

How is number needed to treat calculated?

A

Number needed to treat = 1 / (absolute risk reduction)

17
Q

Definition

What is number needed to treat?

A

The number of people needed to treat to avoid one case of a specific disease

18
Q

Formula

How is relative risk reduction calculated?

A

Relative risk reduction = ( (cumulative incidence in unexposed) - (cumulative incidence in exposed) ) / (cumulative incidence in unexposed)

19
Q

Definition

What is bias?

A

A systematic deviation from the true estimation of the association between exposure and outcome

20
Q

What are the two main types of bias?

A

Selection and information (measurement) bias

21
Q

Definiton

What is selection bias?

A

A systematic error in either the selection of study participants of the allocation of participants to different study groups

22
Q

Definition

What is information (measurement) bias?

A

A systematic error in the measurement or classification of either the exposure or outcome

23
Q

What are the sources of information bias?

A

Observer, participant and/or instrument

24
Q

Definition

What is confounding?

A

The situation where a factor is associated with the exposure of interest and independently influences the outcome, but does not lie on the causal pathway

25
Q

What are the factors to consider when assessing causality?

A

Strength of association
Dose-response - the higher the exposure, the higher the risk of disease
Consistency
Temporality - does exposure precede the outcome?
Reversibility (experiment) - removal of exposure reduces risk
Biological plausability

26
Q

What type of study is this?

Investigators find a high level of correlation between levels of socioeconomic deprivation and cardiovascular mortality across electoral wards in the UK.

A. Cohort study
B. Case-control study
C. Case series
D. Case report
E. Meta-analysis
F. Randomised controlled trial
G. Cross-sectional study
H. Ecological study
I. Systematic review
J. Migration study

A

H. Ecological study

27
Q

What type of study is this?

Researchers set out to examine the association between alcohol consumption and stroke. They identify all new patients admitted with stroke and compare their alcohol consumption with patients admitted for elective surgery.

A. Cohort study
B. Case-control study
C. Case series
D. Case report
E. Meta-analysis
F. Randomised controlled trial
G. Cross-sectional study
H. Ecological study
I. Systematic review
J. Migration study

A

B. Case-control study

28
Q

What type of study is this?

General practitioners set up a study to estimate the prevalence of depression within their registered population. They decide to start with a random sample of adults aged 45-74 years.

A. Cohort study
B. Case-control study
C. Case series
D. Case report
E. Meta-analysis
F. Randomised controlled trial
G. Cross-sectional study
H. Ecological study
I. Systematic review
J. Migration study

A

G. Cross-sectional study

29
Q

Which term best describes the measure being used?

In a randomised controlled trial, the time at risk was determined from entry to the study to various end points

A. Attributable risk
B. Case-fatality rate
C. Cumulative incidence
D. Incidence rate
E. Odds ratio
F. Person-years
G. Prevalence
H. Absolute risk reduction
I. Relative risk
J. Number needed to treat

A

F. Person-years

30
Q

Which term best describes the measure being used?

For patients with meningococcal meningitis, the risk of dying has been estimated to vary from 5-10%

A. Attributable risk
B. Case-fatality rate
C. Cumulative incidence
D. Incidence rate
E. Odds ratio
F. Person-years
G. Prevalence
H. Absolute risk reduction
I. Relative risk
J. Number needed to treat

A

B. Case-fatality rate

31
Q

Which term best describes the measure being used?

In a case-control study of recent alcohol consumption and road traffic accidents, the measure of association was substantially greater than 1 and indicates that there is a positive association between exposure and outcome

A. Attributable risk
B. Case-fatality rate
C. Cumulative incidence
D. Incidence rate
E. Odds ratio
F. Person-years
G. Prevalence
H. Absolute risk reduction
I. Relative risk
J. Number needed to treat

A

E. Odds ratio

32
Q

Which term is most appropriate to the issue described re: causation?

Researchers set out to examine the hypothesis that stress causes hypertension using hypertensive and normotensive individuals in a case-control study. The study design is however criticised because of concerns regarding the temporal sequence of events .

A. Bias
B. Chance
C. Confounding
D. Specificity
E. Reverse causality
F. Dose-response
G. Strength of association
H. Reversibility
I. Biological plausibility
J. Consistency

A

E. Reverse causality

33
Q

Which term is most appropriate to the issue described re: causation?

A study reports an association between coffee consumption and cancer. However, subsequent studies find that there is a clear association between smoking and coffee consumption.

A. Bias
B. Chance
C. Confounding
D. Specificity
E. Reverse causality
F. Dose-response
G. Strength of association
H. Reversibility
I. Biological plausibility
J. Consistency

A

C. Confounding

Phase 3a (10 decks)

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