Introduction to epidemiology

Question 1

What are mortality rates?

Answer 1

the number of deaths in a given area or time period or from a particular disease

Question 2

What statistics are needed for mortality rates?

Answer 2

• a dominator population

- timeframe

Question 3

How is the incidence rate calculated?

Answer 3

no. of new people with outcome over a time period / total person-time for people in a group at risk
x 100,000

Question 4

What is incidence?

Answer 4

number of new cases

Question 5

What is prevalence?

Answer 5

proportion of population that has a disease

Question 6

What are the two types of prevalence?

Answer 6

point

period

Question 7

How is point prevalence rate calculated?

Answer 7

no. of people with outcome at a point in time / total number of people in the group
x 100

Question 8

How is period prevalence rate calculated?

Answer 8

no. of people with outcome during a time period / average number of people in group
x 100

Question 9

What does sporadic mean?

Answer 9

occasional cases occurring irregularly

Question 10

What does endemic mean?

Answer 10

persistent background level of occurrence

Question 11

What does epidemic mean?

Answer 11

occurrence in excess of the expected level for a given time period

Question 12

What does pandemic mean?

Answer 12

epidemic occurring in or spreading over more than one continent

Question 13

What are the different types of exposures?

Answer 13

no-modifiable
modifiable
interventions

Question 14

How is the risk calculated?

Answer 14

number of outcomes in a group / number of people in the group
x 100

Question 15

How is relative risk calculated?

Answer 15

risk in exposed / risk in unexposed

Question 16

How is relative risk reduction calculated?

Answer 16

(1 - relative risk) x 100

Question 17

How is absolute risk reduction calculated?

Answer 17

risk in unexposed - risk in exposed

Question 18

How is number needed to treat calculated?

Answer 18

1 / absolute risk reduction

Question 19

How does the hierarchy of evidence work?

Answer 19

those at the top of the pyramid are more likely to influence clinical practice

Question 20

How does a cross-sectional study work?

Answer 20

1. sample a population
2. estimate the proportion
3. use data

Question 21

How does a case-control study work?

Answer 21

1. select cases with an outcome
2. select controls without an outcome
3. explore exposures in cases and controls
4. compare exposures to work out cause

Question 22

How does a cohort study work?

Answer 22

1. select people without an outcome
2. classify according to exposure
3. compare risk of disease in exposed and unexposed

Question 23

How does a randomised controlled trial work?

Answer 23

1. random allocation
2. compare risk or outcome in intervention and control groups
3. used to test new drugs

Question 24

What is a confounding variable?

Answer 24

one which can cause disease under study and also associated with the exposure of interest

Question 25

What are the aspects of causality?

Answer 25

strength 
consistency 
temporality 
biological gradient
plausibility 
experiment 
coherence 
analogy