Lecture 3.6 Relative and Absolute Measures

_____ is defined as the number of new adverse events in a defined population divided by the population at risk for the event.

Risk

_____ is defined as the number of new cases of events divided by the total number in the population at risk.

Cumulative incidence

Another term for cumulative incidence is _____.

Incidence proportion

The range for cumulative incidence is _____.

0 to 1

_____ is defined as the number of new cases of events divided by the total "person-time" of observation.

Incidence rate

Another term for incidence rate is _____.

Incidence density

The range for incidence rate is _____.

0 to infinity

Cumulative incidence and incidence rate have the same _____ but different _____.

Numerators

Denominators

_____ is defined as the actual time each individual is observed.

"Person time"

Give an example of "person time."

Subjects recruited at different times

Subjects may emigrate/die

Subjects may choose to leave

Which is more accurate?

A) Cumulative incidence

B) Incidence rate

B) Incidence rate

Which incoporates "person-time?"

A) Cumulative incidence

B) Incidence rate

B) Incidence rate

_____ is the total number of individuals in a population who have a disease/condition at a specific time period.

Prevalence

_____ is the number of individuals who develop a specific disease or experience health-related events during a particular time period.

Incidence

Which of the following is expressed as a percentage of a population?

A) Incidence

B) Prevalence

B) Prevalence

Which of the following considers ALL cases?

A) Incidence

B) Prevalence

B) Prevalence

Which of the following considers NEW cases?

A) Incidence

B) Prevalence

A) Incidence

The formula for _____ is risk in exposed divided by risk in non-exposed.

Relative risk (RR)

What is the relative risk if the exposed group had a 50% increased risk compared the non-exposed group?

1.5

What is the relative risk if the exposed group had 3 times the risk compared to the non-exposed group?

3

What is the RR if the risk in exposed is equal to the risk in non-exposed?

A) 1

B) >1

C) <1

A) 1

What is the RR if the risk in exposed is greater than the risk in non-exposed?

A) 1

B) >1

C) <1

B) >1

What is the RR if the risk in exposed is less than the risk in non-exposed?

A) 1

B) >1

C) <1

C) <1

What is the interpretation if RR = 1?

A) No association

B) Positive association

C) Negative association

A) No association

What is the interpretation if RR > 1?

A) No association

B) Positive association

C) Negative association

B) Positive association

What is the interpretation if RR < 1?

A) No association

B) Positive association

C) Negative association

C) Negative association

If RR has a negative association, the explanation should be given in terms of _____.

Relative risk reduction (RRR)

The formula for _____ is 1 - RR.

Relative risk reduction (RRR)

The formula for _____ is the odds that a CASE was exposed divided by the odds that a CONTROL was exposed.

Odds ratio (OR)

The formula for odds ratio (OR) is the odds that a _____ was exposed divided by the odds that a _____ was exposed.

Case

Control

_____ is defined as the probability that the event will occur to the probability that the event will not occur.

Odds

The OR will provide a good estimate for RR when the outcome is _____ or if the effect size is _____.

Rare

Small

The formula for _____ is 1 divided by the RR of survival.

RR of death

_____ can be used to calculate number needed to treat (NNT) or number needed to harm (NNH).

Absolute risk difference

The _____ describes how many patients needed to be treated to result in 1 "treatment effect" or "event avoided?"

NNT/NNH

NNT stands for _____.

NNH stands for _____.

ARR stands for _____.

Number needed to treat

Number needed to harm

Absolute risk difference

The formula for _____ is 1 divided by ARR.

NNT

Which of the following is true about a low NNT/NNH value?

A) Higher incidence of condition

B) Lower incidence of condition

A) Higher incidence of condition

Which of the following is true about a high NNT/NNH value?

A) Higher incidence of condition

B) Lower incidence of condition

B) Lower incidence of condition