Introduction to Epidemiology

Question 1

What is epidemiology?

Answer 1

The study of that which fall upon people.

Question 2

What are examples of denominators?

Answer 2

Health board, city, hospital and disease register.

Question 3

Why is the denominator important in epidemiological studies?

Answer 3

Without a denominator, population and time death rates are meaningless.

Question 4

Define prevalence.

Answer 4

Proportion of population that has the disease.

Question 5

What does incidence identify?

Answer 5

Useful for identifying causes of diseases.

Question 6

What does prevalence identify?

Answer 6

Identifies disease burden.

Question 7

When does incidence occur?

Answer 7

By definition, only in people without the disease.

Question 8

Define sporadic.

Answer 8

Occasional cases occurring irregularly.

Question 9

Define endemic.

Answer 9

Persistent background level of occurrence.

Question 10

Define epidemic.

Answer 10

Occurrence in excess of the expected level for a given time period.

Question 11

Define pandemic.

Answer 11

Epidemic occurring in or spreading over more than one continent.

Question 12

What are examples of non-modifiable exposures?

Answer 12

Age, sex and genotype.

Question 13

What are examples of modifiable exposures?

Answer 13

Smoking, weight, diet and alcohol consumption.

Question 14

What are examples of interventions?

Answer 14

Drug therapy, surgery and lifestyle advice.

Question 15

What is the risk equation?

Answer 15

(Number of outcomes in a group/number of people in a group) x 100.

Question 16

What is the relative risk equation?

Answer 16

Risk in exposed/risk in unexposed.

Question 17

What is the relative risk reduction equation?

Answer 17

(1-relative risk)x100.

Question 18

What is the absolute risk reduction equation?

Answer 18

Risk in unexposed-risk in exposed.

Question 19

What is the number needed to treat equation?

Answer 19

1/absolute risk reduction.

Question 20

When is the odds ratio used?

Answer 20

Commonly used estimate of risk ratio.

Question 21

What is rate ratio?

Answer 21

Ratio between two mortality rates, hospitilisation rates.

Question 22

What is the hazard ratio?

Answer 22

A special kind of rate ratio (survival analysis).

Question 23

What are confidence intervals?

Answer 23

A range of plausible values.

Question 24

What does the confidence interval tell you?

Answer 24

Values near the limits are less plausible than those in the middle and the wider the interval the greater the uncertainty.

Question 25

When are confidence intervals useful?

Answer 25

Very useful in appraising published research.

Question 26

What would you do in a cross-sectional study?

Answer 26

Sample a population.

Question 27

What would you do in a case-control study?

Answer 27

Select cases with an outcome, but select controls without an outcome.

Question 28

What would you do in a cohort study?

Answer 28

Select people without an outcome.

Question 29

What would you compare in a cohort study?

Answer 29

Risk of disease in exposed and unexposed.

Question 30

What would you compare in a randomised controlled trial?

Answer 30

Compare risk of outcome in intervention and control groups.

Question 31

What is the objective in a randomised controlled trial?

Answer 31

Treatment effect.

Question 32

What is the objective in a cohort study?

Answer 32

Cause, prognosis and incidence.

Question 33

What is the objective in a case-control study?

Answer 33

Cause.

Question 34

What is the objective in a cross-sectional study?

Answer 34

Prevalence

Question 35

Which study designs look into the future?

Answer 35

RCT and cohort.

Question 36

What are the 2 types of cohort study?

Answer 36

Retrospective an prospective.

Question 37

Which study designs look into the past?

Answer 37

Case-control and cross-sectional.

Question 38

When is a causal link more likely?

Answer 38

With strong associations, in different studies and different sub-groups.

Question 39

How is specificity linked to causal links?

Answer 39

A causal link is more likely when a disease is associated with one specific factor.

Question 40

How is temporality linked to causal links?

Answer 40

A CL is more likely if exposure to the putative cause has been shown to precede the outcome.

Question 41

How is a biological gradient linked to causal links?

Answer 41

A CL is more likely if different levels of exposure to the putative factor lead to different risk of acquiring the outcome.

Question 42

How is plausibility linked to causal links?

Answer 42

A CL is more likely if a biologically plausible mechanism is likely or demonstrated.

Question 43

How does coherence effect causal links?

Answer 43

A CL is more likely if the observed association conforms with current knowledge.

Question 44

How does experiment effect causal links?

Answer 44

A CL is very likely if removal of the putative factor leads to a reduced risk of acquiring the outcome.

Question 45

How does analogy effect causal links?

Answer 45

A CL is more likely if an analogy exists with other diseases, species or settings.