Epidemiology/Biostatistics I

Question 1

cross sectional study

Answer 1

collect data from group of people

• assess frequency of disease
• at particular point in time

asks what is happening?

Question 2

case control study

Answer 2

retrospective

compare group with disease to group without

look for prior exposure

ask what happened?

odd ratio - patient with COPD had higher odds of smoking history than those without COPD

Question 3

cohort study

Answer 3

compare group with give exposure or risk fx to group without exposure

look to see if exposure increased likelihood of disease

relative risk - smoker had higher risk of developing COPD than nonsmoker

Question 4

twin concordance study

Answer 4

compare frequency with which both monozygotic twins or both dizoygotics developed disease

nature vs. nurture

Question 5

adoption study

Answer 5

compare siblings raised biological vs. adoptive

Question 6

clinical trial

Answer 6

experiment with humans

therapeutic benefit of 2 or more treatments, or of treatment and placebo

better study - if random, controlled, double blinded

Question 7

triple blinded

Answer 7

involves researching doing study

Question 8

phases of drug trials

Answer 8

phase 1 - safety - toxicity, PK, PD

phase 2 - does it work - small number patients with disease of interest

phase 3 - large number of patients - good or better - compared to current standard of care

phase 4 - can it stay - rare and long term adverse affects - postmarketing surveillance of patient after tx approved

Question 9

sensitivity

Answer 9

true positive

TP / all with disease

screening test

Question 10

specificity

Answer 10

true negative

TN / all without disease

confirmatory test

Question 11

positive predictive value

Answer 11

TP / all positives

Question 12

negative predictive value

Answer 12

TN / all negatives

Question 13

incidence

Answer 13

number new cases during time period

Question 14

prevalence

Answer 14

number of cases at certain time

Question 15

short duration disease

Answer 15

incidence kind of equals prevalence

Question 16

odds ration

Answer 16

case control study

odd group with disease exposed to risk factor
-divided by odds that group without disease was exposed

Question 17

relative risk

Answer 17

cohort study

risk developing disease in exposed group
-divided by risk in unexposed group

Question 18

attributable risk

Answer 18

difference in risk between exposed and unexposed group

proportion of disease occurences that are attributable to exposure

Question 19

relative risk reduction

Answer 19

proportion of risk reduction attributable to intervention compared to control

Question 20

absolute relative risk

Answer 20

difference in risk attributable to intervention as compared to control

Question 21

number needed to treat

Answer 21

number of patient need to be treated for 1 patient to benefit

Question 22

number needed to harm

Answer 22

number of patient needed to exposed to risk fx for 1 patient to be harmed

Question 23

precision

Answer 23

consistent - all values close together

reliability

not close to the bulls eye but close together

Question 24

accuracy

Answer 24

validity

absence of systematic error

close to actual measurement - bulls eye

Question 25

selection bias

Answer 25

error assigning subject to group

-unrepresentative sample

Question 26

berkson bias

Answer 26

study from hospital - people less healthy

Question 27

healthy worker effect

Answer 27

study population healthier then general population

Question 28

non-response bias

Answer 28

participant differ from non-responders

Question 29

recall bias

Answer 29

awareness of disorder alter recall by subject

patient with disease recall exposure after learning similar cases

Question 30

measurement bias

Answer 30

info gathered in a way that distorts it

miscalibrated scale - overstate weight of subject

Question 31

procedure bias

Answer 31

subject in different group not treated same

Question 32

observe-expectancy bias

Answer 32

researcher belief in tx changes outcome of tx

Question 33

confounding bias

Answer 33

factor is related to both exposure and outcome, but not causal pathway

factor distorts or confuses effect of exposure on outcome

Question 34

lead time bias

Answer 34

early detection confused with increased survival