Chen Lecture

Question 1

What does the sensitivity of a test imply?

Answer 1

-the ability of a test to identify correctly those who have the disease
-it shows the proportion of people who have the disease and are actually tested “positive”
-shows the how well the test identifies true positives

Question 2

What is 100%-%sensitivity=?

Answer 2

% false negative

Question 3

What does the specificy of a test imply?

Answer 3

-ability of test to identify correctly those who DON’T have the disease
-shows how well the test identifies people who are true negatives

Question 4

What is 100%-% specificity?

Answer 4

% false positive

Question 5

What is morbidity?

Answer 5

rate of disease in population

Question 6

What statistical measures can be used to describe morbidity?

Answer 6

-incidence rate
-prevalence
-attack rate

Question 7

What is incidence rate?

Answer 7

number of NEW CASES of disease that occur during a specified period of time in a population AT RISK for developing the disease

Question 8

What is prevalence?

Answer 8

number of people with disease at a specific time divided by total number of people in the population

Question 9

Does prevalence include new cases of the disease occurring?

Answer 9

yes!

Question 10

What is attack rate?

Answer 10

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

Question 11

What is mortality rate?

Answer 11

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

Question 12

What is standardization?

Answer 12

-method used to adjust for differences in population characteristics when comparing disease or mortality rates b/w two or more groups

Question 13

What is direct standardization?

Answer 13

estimates rate of disease of death in the study population as if it had the same age distribution as standard population

Question 14

What is indirect standardization?

Answer 14

compares the observed rate of disease of death in the study population to the expected rate based on a standard population

Question 15

What is the difference between direct and indirect standardization?

Answer 15

-direct: uses characteristics from standard population to estimate rate in study population
-indirect: compares the rate in study population to what is should be based on standard population

Question 16

What are confidence intervals?

Answer 16

numerical range used to describe how reliably study results reflect the entire population

Question 17

True or false: wider confidence intervals indicate higher precision and credible values.

Answer 17

FALSE: wider confidence intervals indicate LOW precision and LESS credible values

Question 18

For differences, if the confidence interval includes 0, what does this mean?

Answer 18

the results is NOT statistically significant

Question 19

For ratios, if the confidence interval includes 1, what does this mean?

Answer 19

the result is NOT statistically significant

Question 20

What is a risk ratio?

Answer 20

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

Question 21

What does a risk ratio >1 indicate?

Answer 21

-risk in exposed group > risk in UNexposed group
-positive association, possible risk-enhancing exposure

Question 22

What does a risk raito <1 indicate?

Answer 22

-risk in exposed group < risk in UNexposed group
-negative association, possibly protective exposure

Question 23

What is a risk ratio =1 indicate?

Answer 23

-risk in exposed group=risk in unexposed group
-no association

Question 24

What is an odds ratio?

Answer 24

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

Question 25

What is the general formula for odds ratio?

Answer 25

(odds of exposure in cases) ________________________________ (odds of exposure in control)

Question 26

What does an odds ratio =1 indicate?

Answer 26

no association

Question 27

What does an odds ratio <1 indicate?

Answer 27

-exposure decreases odds of disease -negative association, possibly protective exposure

Question 28

What does an odds ratio >1 indicate?

Answer 28

-exposure increases odds of disease -positive association; possible risk-enhancing exposure

Question 29

Is odds ratio prospective or retrospective?

Answer 29

retrospective; used in case control studies

Question 30

What is attributable risk?

Answer 30

-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 31

What is population attributable risk?

Answer 31

-AR of an entire population whether or not all in the population have direct exposure -the impact of removing exposure would have on total population

Question 32

What is a hazard ratio?

Answer 32

rate at which unfavorable events occur

Question 33

What is the general formula for HR?

Answer 33

proportion of people who were exposed and GOT the disease / proportion of people who were NOT exposed but still got the disease

Question 34

What does a HR >1 mean?

Answer 34

exposure increases event rate of disease

Question 35

What does a HR <1 mean?

Answer 35

exposure decreases event rate of disease

Question 36

What is number needed to treat?

Answer 36

number of patients who would have to receive the treatment for one of them to benefit

Question 37

What is number needed to harm?

Answer 37

number of patients who receive a treatment before 1 adverse event occurs

Question 38

Do we want a higher or lower NNH?

Answer 38

higher! we want the chances to harming a patient to be more rarer (need to treat more patients before a bad event happens)

Question 39

Do we want higher or lower NNT?

Answer 39

lower! we want to the chances of treating the patient to be more probable (need to treat less patients for one to actually benefit from treatment)