Lecture 11 - Risks and Risk Factors

Question 1

Define Risk

Answer 1

The probability of some untoward event (e.g. disease, death)

Question 2

Define Risk Factors

Answer 2

Characteristics or behaviors associated with an increased risk of becoming diseased (e.g. smoking, being male)

Question 3

What are types of Risk Factors?

Answer 3

• Non-modifiable (e.g. age, sex, family history, genotype)

- Modifiable (e.g. smoking, hypertension)

Question 4

What are the uses of risk?

Answer 4

• to predict the occurrence of disease
• to identity possible causes of disease
• to help in the diagnosis of disease
• to aid in the prevention of disease
• to quantify benefit or harm of interventions

Question 5

Is NNT better/worse for high risk groups (more likely that benefits > harms)?

Answer 5

better

Question 6

Is NNT better/worse for low risk groups (more likely that benefits > harms)?

Answer 6

worse

Question 7

Define Attributable Risk (AR)

Answer 7

The risk of an outcome attributable to a given exposure.

AR = Incidence in exposed group (%) – Incidence in unexposed group (%)

Question 8

What is the formula for attributable proportion among exposed (ape)?

Answer 8

[Incidence in exposed group – Incidence in unexposed group] / Incidence in exposed group

Question 9

What does attributable proportion among exposed describe?

Answer 9

The proportion of outcome among exposed that is due (attributable) to exposure or that would be prevented if exposure were eliminated

Question 10

What does attributable proportion among total describe (apt)?

Answer 10

APT describes the proportion of disease among total population that would be eliminated if exposure were eliminated

Question 11

What is the formula for attributable proportion among total population?

Answer 11

[Incidence in exposed group – Incidence in unexposed group] / Total Population

Question 12

What does Relative Risk Measure?

Answer 12

Relative Risk measures the effect of exposure on the chances of developing a disease

Question 13

What is the formula for Relative Risk?

Answer 13

RR = Incidence in exposed / Incidence in non-exposed

*you need a RCT or cohort study to calculate incidence (you cannot calculate it in a case-control study because you select cases and controls)

Question 14

In case-control studies, since you cannot use Relative Risk, what must you do?

Answer 14

calculate odds ratio (OR)

Question 15

What is formula for odds ratio?

Answer 15

OR = [ratio of the odds that a case was exposed] / [ratio of the odds that a control was exposed]

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