Study designs (epidemiology) Oct5 M2

Question 1

2 types of study designs (broad categories)

Answer 1

descriptive vs analytical studies

Question 2

3 types of descriptive studies

Answer 2

case series, cross-sectional studies, ecological studies

Question 3

case series study def

Answer 3

present cases (exposures, outcomes), no control, low stat impact

Question 4

ecological studies def

Answer 4

superpose 2 descriptive studies (disease and exposure), correlation but not causality, good for hypothesis generation

Question 5

cross-sectional studies def

Answer 5

snapshot at one moment. prevalence.

Question 6

2 types of analytic studies

Answer 6

observational and experimental

Question 7

3 types of observational studies

Answer 7

cross-sectional, case-control, cohort

Question 8

cross-sectional study design

Answer 8

take population, take data n exposure and disease, classify patients in positive negative disease and exposure groups

Question 9

cross-sectional studies good and bad

Answer 9

good: helps for fixed exposure (age, gender)
bad: don’t know if exposure or outcome came first (bc snapshot in time)

Question 10

case control study design

Answer 10

look back in time at defined pop. of cases, who was exposed. of controls, who was exposed

Question 11

case-control study rare disease and exposure capabilities

Answer 11

can determine exposure in rare diseases

can’t deal with rare exposures

Question 12

case-control study answers what question in lung cancer

Answer 12

in people with lung cancer, likelihood of smoking

Question 13

cohort study: 2 designs and important point

Answer 13

retrospective (study after exposure and disease occur)

prospective (study before disease)

Question 14

cohort study general design

Answer 14

take population, have expose and not exposed. look at who will get disease or not

Question 15

cohort study: rare disease and exposure capabilities

Answer 15

can’t look at rare disease

can look at rare exposure

Question 16

problem in cohort studies**

Answer 16

loss to follow up can create selection bias

Question 17

experimental study: 1 type

Answer 17

RCT

Question 18

RCT vs observational studies

Answer 18

produce same odds ratio on average

Question 19

relative risk general deff

Answer 19

ratio of probability of disease in exposed group to non exposed group

Question 20

relative risk includes what terms and word for all these terms

Answer 20

rate ratio, hazard ratio, risk ratio, odds ratio: MEASURES OF ASSOCIATION

Question 21

rate ratio def

Answer 21

incidence rate (x per person year) in exposed div. incidence rate in non exposed

Question 22

hazard ratio def

Answer 22

time to disease in exposed div. time to disease in non exposed

Question 23

risk ratio def

Answer 23

cumulative incidence in exposed div cumulative incidence in non exposed

Question 24

odds ratio def

Answer 24

odds of exposure in the cases vs odds of exposure in the controls

Question 25

4 measures of impact

Answer 25

attributable risk, attributable fraction, population attributable risk, population attributable fraction

Question 26

what we mean by relative risk

Answer 26

odds ratio

Question 27

attributable risk def

Answer 27

diff in incidence RATES or in risks (cumulative incidence). how much disease we could prevent by removing exposure

Question 28

attributable fraction def (2)

Answer 28

(incidence in exposed - incidence in unexposed) div. incidence in exposed

attributable risk div. incidence in exposed

Question 29

population attributable risk def

Answer 29

incidence in all pop. - incidence in unexposed

Question 30

population attributable fraction def

Answer 30

(incidence in all pop. - incidence in unexposed) div. incidence in all pop

Question 31

how attributable fraction vs pop. attributable fraction differ generally

Answer 31

pop. attrib. fraction is lower bc you include some people without the exposure

Question 32

how to calculate attributable fraction in case control study

Answer 32

(odds ratio - 1) div. odds ratio

Question 33

how to calculate attributable risk in case control study

Answer 33

CAN’T CALCULATE IT. (need incidence but didn’t follow)

Question 34

how to calculate the population attributable fraction in case control studies

Answer 34

AF (attrib. fraction) x prevalence of exposure in disease (of diseased, how many have been exposed)

Question 35

how to calculate attributable fraction in cohort studies (2)

Answer 35

(incidence in exposed - inc. in unexp.) div inc. in exposed

(RR-1) div. RR

Question 36

which observ study is better to study rare disease

Answer 36

case control

Question 37

which observ study is better to study rare exposures

Answer 37

cohort study

Question 38

which observ study is better to study multiple outcomes

Answer 38

cohort study (bc case control have to pick 1 outcome)

Question 39

which observ study is better to study multiple exposures

Answer 39

case control study (bc cohort have to pick 1 exposure)