Introduction To Epidemiology

Question 1

Prevalence of disease in a population

Answer 1

Proportion of the population who have the disease at the relevant time;
Number of existing cases/ Total population

Question 2

Period prevalence

Answer 2

Proportion of the population affected over a given period

Question 3

Incidence of a disease

Answer 3

Number of new cases of disease occurring in a given population over a given period of time;
New cases/ Total population

Question 4

Risk

Answer 4

Probability that an event will occur

Risk = A /(A+B)

Question 5

Rate

Answer 5

Measure of frequency;

Number of events occurring in a population over a period of time

Question 6

Odds

Answer 6

A/B

Question 7

Risk ratio

Answer 7

Probability of one event/probability of another event

Question 8

Risk difference

Answer 8

Subtracting one risk from another

Question 9

Attributable risk

Answer 9

Difference in risk of a condition between exposed population and an unexposed population assuming that the exposure is causally related to the disease.

Question 10

NNT

Answer 10

Average number of patients that need to be treated to prevent one additional bad outcome
1/ reduction in absolute risk