Measures of Effect

Question 1

What is ‘Attributable Risk’?

Answer 1

Frequency in exposed - Frequency in unexposed

• Calculates the frequency of the outcome in exposed individuals that can be attributes to the exposure
• Assumes the relationship is causal
• Can be calculated using prevalence, risk or incidence rate

Question 2

What is ‘Attributable Fraction’?

Answer 2

(Frequency in exposed - Frequency in unexposed) / Frequency in exposed

• Calculates the attributable risk as a proportion of the incidence of an outcome in exposed individuals that can be attributed to exposure
• Related to relative risk = 1 - (1/RR)

Question 3

What is ‘Population Attributable Risk’?

Answer 3

Frequency in population - Frequency in unexposed

• Calculates the frequency of the outcome in population that can attributed to the exposure taking into account the actual population frequency

Question 4

What is ‘Population Attributable Fraction’?

Answer 4

(Frequency in population - Frequency in unexposed) / Frequency in population

• Indicates the proportion of the outcome that could be prevented if the exposure were to be eliminated if the exposure could be eliminated from the population

Question 5

What is the ‘Preventable Fraction’?

Answer 5

(Frequency in Unexposed - Frequency in Exposed) / Frequency in Unexposed

• Proportion of outcome in individuals that can be prevented by exposure
• Related to relative risk = 1 - RR