Lecture 4

Question 1

Sensitivity

Answer 1

The ability of a test to identify who has the disease

TP / (TP + FN)

100% - % sensitivity = % false negative

Question 2

Specificity

Answer 2

The ability of a test to identify those who do NOT have the disease

TN / (TN + FP)

100% - % specificity = % false positive

Question 3

Morbidity

Answer 3

rate of disease in a population

Can be described using:
- cumulative incidence proportion
- incidence rate
- prevalence
- attack rate

Question 4

Cumulative incidence proportion

Answer 4

Period of time during which all individuals in a population are considered to be at risk for the outcome

measure of risk

Question 5

Incidence Rate

Answer 5

number of NEW cases of a disease that occur during a specified period of time in a population at risk for developing the disease

measure of morbidity

Question 6

Prevalence

Answer 6

Number of affected persons present in the population at a specific time divided by the number of persons in the population at that time

measure of morbidity

Question 7

Attack Rate

Answer 7

the number of people that are exposed to something and get the associated outcome, divided by the total number of people exposed

Measure of morbidity

Question 8

Mortality Rate

Answer 8

number of deaths from a cause in a certain population over a specific period of time

Question 9

Standardization

Answer 9

set of techniques used to remove the effects of differences when comparing two or more populations

Question 10

Direct standardization example

Answer 10

rate of disease/death that would have been observed in the study population if it had the same age distribution as the standard population

Question 11

Indirect standardization example

Answer 11

compares the rate of death/disease observed in the study population to the expected rate from the standard population

Question 12

Risk Ratio (Relative risk, RR)

Answer 12

ratio of the risk of disease in exposed individuals to the risk of disease in unexposed individuals

Question 13

RR interpretation

Answer 13

= 1 : risk in exposed group is equivalent to risk in unexposed group

< 1 : risk in exposed group is less than risk in unexposed group

> 1 : risk in exposed group is greater than risk in unexposed group

Question 14

Odds Ratios (OR)

Answer 14

the ratio of the probability of occurrence of an event to that of non-occurrence

Question 15

OR interpretation

Answer 15

=1 : no association

<1 : negative association, exposure decreases odds of disease

> 1 : positive association. exposure increases odds of disease

Question 16

RR vs OR: study utilization

Answer 16

RR: prospective or cohort

OR: retrospective, case-control, multiple logistic regression

Question 17

Attributable Risk

Answer 17

the amount or proportion of disease incidence or risk that can be attributed to a specific exposure

if the exposure were removed, how much of the disease burden will be reduced

Question 18

Population Attributable Risk

Answer 18

The attributable risk of an entire population whether or not all in the population have direct exposure

What would be the impact of removing an exposure on the total population?

Question 19

Hazard Ratio (HR)

Answer 19

rate at which an unfavorable evet occurs; commonly used in survival analysis

Question 20

HR interpretation

Answer 20

=1 : No association

<1 : Negative association, exposure decreases event rate

> 1 : Positive association, exposure increases event rate

Question 21

Confidence intervals

Answer 21

numerical range used to describe how reliably study results reflect the entire population
- confidence level reported ahead of the range indicates the probability that the range is accurate

wide range = low precision
narrow range = high precision

if the range includes 0 -> not statistically significant

Question 22

Number Needed to Treat (NNT)

Answer 22

Number of patients who would have to receive a treatment for one of them to benefit

Question 23

Number Needed to Harm

Answer 23

Number of patients who receive a treatment before 1 ADE occurs