EPIDEMEOLOGY - Overview

Question 1

What is epidemiology?

Answer 1

The study of the occurrence and distribution of diseases in populations and the factors which influence disease occurrence

Question 2

What is the incidence rate of disease?

Answer 2

The incidence rate of disease tracks new cases of disease that appear over a period of time, yielding information about the risk of contracting disease

Question 3

How would you calculate the incidence rate?

Answer 3

(number of new cases) / (total animal time at risk)

Question 4

How would you calculate the cumulative incidence rate?

Answer 4

(number of new cases) / (total number of animals present)

Question 5

What is the prevalence rate of disease?

Answer 5

The prevalence rate displays the proportion of a population that is affected by a disease within a snapshot of time, yielding information on how widespread a disease is

Question 6

How would you calculate the prevalence rate?

Answer 6

(number of cases of disease) / (total number of animals present)

Question 7

List different types of epidemiology study designs in order of strength of evidence

Answer 7

DESCRIPTIVE STUDIES:
- Case reports
- Case series
- Survey
ANALYTICAL OBSERVATIONAL STUDIES:
- Cross-sectional
- Case-control
- Cohort
- Hybrid
EXPERIMENTAL OBSERVATIONAL STUDIES:
- Laboratory
- Randomised control trial

Question 8

What is a cohort study?

Answer 8

The observation of a group of exposed and unexposed animals over time

Question 9

What is a case-control study?

Answer 9

The comparison of the exposure history of two groups
- Case group: group with disease
- Control group: group without disease

Question 10

What are the advantages of cohort studies?

Answer 10

• Can observe several diseases simultaneously
• Can obtain an estimate of disease incidence among a wider population

Question 11

What are the disadvantages of cohort studies?

Answer 11

• Requires lots of resources

Question 12

What are the advantages of case-control studies?

Answer 12

• Can study rare diseases
• Can easily obtain background information

Question 13

What are the disadvantages of case-control studies?

Answer 13

• Liable to bias
• Cannot estimate disease incidence across a wider population

Question 14

What are the two measures of association used in epidemiology?

Answer 14

• Relative risk
• Odds ratios

Question 15

What is relative risk?

Answer 15

The probability of contracting disease

Question 16

What are odds ratios?

Answer 16

The difference in the probability of contracting disease depending on the risk factors affecting two groups

Question 17

Which measure of association is used in cohort studies?

Answer 17

Relative risk

Question 18

Which measure of association is used in case-control studies?

Answer 18

Odds ratios

Question 19

How would you calculate relative risk?

Answer 19

(Risk of disease in exposed group)/ (Risk of disease in unexposed group)
(a/a+b)/(c/c+d)

Question 20

How would you calculate odds ratios?

Answer 20

(Risk of disease in exposed group/Risk of disease in unexposed group)
(ad/bc)