Epi Block 2 Real

Front 1

Temporal sequence between expsure and disease is clearly established

Back 1

Cohort

Front 2

Well suited for assessing the effects of rare exposures

Back 2

Cohort

Front 3

Incidence of disease can be calculated

Back 3

Cohort

Front 4

Can examine multiple outcomes of a single exposure

Back 4

Cohort

Front 5

True estimate of risk can be calculated

Back 5

Cohort

Front 6

Money (expensive) is a disadvantage

Back 6

Cohort

Front 7

Subject to loss of follow up

Back 7

Cohort

Front 8

Time consuming (disadvantage)

Back 8

Cohort

Front 9

Cannot be used when stufying a rare disease

Back 9

Cohort

Front 10

Cannot be used when bad records, unreliable data

Back 10

Retrospecive cohort

Front 11

Cannot be used to study chronic disease.

Reason?

Back 11

Cohort.

Bcuz of the long gap between exposure and outcome

Front 12

Cannot be used when theres no clear distinction between exposed and unexposed

Back 12

Cohort

Front 13

What are the steps in cohort study?

Back 13

1) Choose design

2) Selection of exposed group

3) Selection of comparison group

4) Follow up

5) Analysis and interpretation

Front 14

For studying diseases with common exposures, what type of population should be used? Give examples

Back 14

Highly compliant and motivated participants.

Ex. doctors, nurses, union members, veterans

Front 15

For studying diseases with rare exposures, what type of population should be used? Give examples

Back 15

Highly exposure groups.

Ex. uranium workers, Chernobyl residents

Front 16

In cohort study, when selecting comparison group, it should be _______________

Back 16

Free from exposure, but similar to the case group

Front 17

How can be thw Hawthorne effect adressed?

Back 17

Using workers, from the same establishment wh are not exposed to the risk factor, as comparison group

Front 18

Selecting population within the same company to compare factory floor workers (exposed) and office workers (not exposed) can diminish ________

Back 18

Hawthorne effect

Front 19

Mention 3 issues of a chort study

Back 19

1) Bias

2) Loss to follow-up

3) Non participation

Front 20

The Less common issue in cohort study is

Back 20

bias (although missclassification and selection bias can still occur)

Front 21

A study that loses __% of participants is ______

Back 21

25% --> flawed

Front 22

Purpose is to determine if the groups differ by eposure

Back 22

Case-control

Front 23

Best study to assess rare diseases

Back 23

Case-control

Front 24

Suitable to study chronic diseases

Back 24

Case-control

Front 25

Cost effective and less time to complete

Back 25

Case-control

Front 26

Many exposure factors can be studied at the same time

Back 26

Case-control

Front 27

ICannot get true estimate of risk

Back 27

Case-control

Front 28

Issues with temporal association

Back 28

Case-control

Front 29

Issues with choosing appropiate controls

Back 29

Case-control

Front 30

Strong potencial for bias

Back 30

Case-control

Front 31

Cofounding is an issue in _______

Back 31

Case-control

Front 32

What are the steps in casecontrol studies?

Back 32

1) Definition and selection of cases

2) Selection of controls

3) Ascetainment of disease and exposure status

4) Analysis

Front 33

The most difficult issue in case-control designs is

Back 33

Selection of controls

Front 34

Mention 3 types of community controls

Back 34

1) Neighborhood controls

2) Best friends controls

3) Spouse or sibling control

Front 35

Issue for selecting hospitalized controls

Back 35

Risk of Cofounders--> are more likely to be smokers, alcoholics and with other high risk behaviors

Front 36

Disadvantages of stratified analysis

Back 36

1) Its extremely cumbersome

2) Difficult to control for more than 1 cofounder at a time

Front 37

"If sex is a cofounder then analyze men and women separately". This is used for:

Back 37

Stratified analysis

Front 38

"If age is a confounder, then analyze data separately for each age group". This is used for:

Back 38

Stratified analysis

Front 39

Incidence cannot be derived

Back 39

Case-control

Front 40

The estimate of relative risk can be calculated

Back 40

Case control

Front 41

Odds ratio can be calculated

Back 41

Case control

Front 42

Equation for odds ratio

Back 42

(A)(D)

---------

(B)(C)

Front 43

Numerator in odds ratio eq is:_________

What about denominator?

Back 43

Numerator: odd of exposure for cases

Denominator: exposure for controls

Remember: A/C

----------

B/D

Front 44

Any systemic error that results in an incorrect estimate of the risk of association between exposure and risk of disease

Back 44

Bias

Front 45

Effects of _______ are difficult to evaluate in tha analysis

Back 45

Bias

Front 46

The time to eliminate bias is when ___________

Back 46

the study is designed

Front 47

Sample selected differs in properties in cases and controls

Back 47

Selection bias

Front 48

Can lead to an over or understimation of risk

Back 48

Recall bias

Front 49

People who are sick tend t think about possible "causes" for their illness. (they remember thing better and clearer)

Back 49

Recall bias

Front 50

Interviewer bias refers to

Back 50

Interviewers who are aware of the study hypothesis are likely to question cases and control differently

Front 51

More probing questions may be asked of cases

Back 51

Interviewer bias

Front 52

Experimenter's expectations are communicated to the subjects, unintentionally

Back 52

Pygmalion effect

Front 53

Subjects may be erroneously categorized with respect to exposure or disease status

Back 53

Misclassification bias

Front 54

Method of collecting information was flawed

Back 54

Measurement bias

Front 55

Bias that use standard sources to validate

Back 55

Misclassification bias

Front 56

Bias that use highly trained personnel, blinded to study hypothesis

Back 56

Interviewer bias

Front 57

Bias that use ne hospitalized control group

Back 57

Recall bias

Front 58

Bias that use control picked from the same source of cases, use mtivated individuals

Back 58

Selection bias

Front 59

Variable that is known to be associated with the outcome (effect)

Back 59

Confounder

Front 60

Mention 5 examples of common confounders:

Back 60

1) age

2) gender

3) tobacco

4)alcohol

5)socio-economic status

Front 61

"If smoking can be a confounder, then only wnroll non-smokers"

Back 61

Restrictions on study subjects

Front 62

Cases and controls are matched by usual confounders so that the factors are equally distibuted in both groups

Back 62

Matching the subjects

Front 63

Each subject seerves as his/her own control

Back 63

Crossover design

Front 64

Steps in clinical trial

Back 64

1) Formulate hypothesis

2) Choose sample size and select participants

3) Do necessary exclusions

4) Random assignment

5) Outcome measurement

Front 65

General group to whom the results will be applicable to

Back 65

Reference group

Front 66

Actual group in whom the study is conducted

Back 66

Experimental population

Front 67

Assignment to treatment group in CT should occur _____________

Back 67

after the study population is chosen and informed consent obtained

Front 68

Used when yo wish to mantain equal numbers of population characteristic in each group (ex. gender)

Back 68

Block randomization

Front 69

The reason of randomization is to

Back 69

reduce bias due to known and unknown confounders

Front 70

Only the experimenter knows the assignment of subject; subjects don't

Back 70

Single blind

Front 71

Neither the experimenter nor the subjects know the assignments

Back 71

Double blind

Front 72

A ________ blind trial provides the best protection agains bias

Back 72

double or triple

Front 73

Mention 4 factors that can affect the outcome of RCT

Back 73

1) Errors in hypothesis testing

2) Sample size

3) Post randomization changes in groups

4) Analysis of data

Front 74

Individuals in one treatment arm may drop out at higher rates due to factors such as side effects

Back 74

Compliance bias

Front 75

Study participants may drop out, switch tx groups

Back 75

Migration bias

Front 76

Analyses in the medical literature should be always be analyzed and reported by ____________ method

Back 76

Intention to treat

Front 77

Ability of a treatment to work in the ideal study setting

Back 77

Efficacy

Front 78

Ability of the treatment to work under realistic circumstances

Back 78

Effectiveness

Front 79

For efficacy trails, _______ analysis can be used.

Back 79

explanatory

Front 80

For effectiveness trials, _________ analysis can be used

Back 80

Intention to treat

Front 81

A record is kept of simple outcomes like symptoms score relief, etc. Only possible in conditions which occur frequently and resolve quickly

Back 81

Trials of "n" equal to 1

Front 82

Clinical trial done when pat have migraine, asthma, etc (quickly resolving diseases)

Back 82

Trials n=1

Front 83

Phase that uses animal studies

Back 83

Pre-clinical

Front 84

Phase that test healthy human volunteers

Back 84

Phase 1

Front 85

Identify toxicities, tolerated doses, describe pharmacology (metabolism, excretion)

Back 85

Phase 1

Front 86

Phase that use subjects woth disease

Back 86

Phase 2

Front 87

Validate toxicity and dosage data

Back 87

Phase 2

Front 88

Phase when randomized trials for comparison with standard therapy

Back 88

Phase 3

Front 89

Phase that assess side effects associated w long-term use

Back 89

Phase 4

Front 90

Phase in which studies are done after drug or tx has been marketed to gather info on the drugs effect

Back 90

Phase 4

Front 91

Informed consent must be obtained from all participants involved in human experiments

Back 91

Declaration of Helsinki

Front 92

Stratey used to identify disease in an unsuspecting population

Back 92

Screening

Front 93

Basic purpose of screening is :

Back 93

to detect disease from a large group of apparently well persons

Front 94

Mention 2 aspects of interpretation of screenings

Back 94

1) Reliability

2) Validity

Front 95

Also called Reproductibility

Back 95

Reliability

Front 96

Mention 3 bias in screening programs

Back 96

1) Lead time bias

2) Lenght bias

3) Selection bias

Front 97

The perception that the case has a longer survival simply bcuz the disease was identified earlier in the natural course of disease

Back 97

Lead time bias

Front 98

Tumors detected by screening programs tend to be slower growing, therefore have a better prognosis

Back 98

Length Bias

Front 99

Misperception that screening itself leads to better outcomes

Back 99

Lenght Bias

Front 100

Individuals who are motivated to participate in screening programs may have a different probability of disease than indviduals who refuse to participate

Back 100

Selection bias

Front 101

Women with family history breastcancer joining screening; more women with illness arefound and more dying of it. When it is applied to general population theresults may be different.

Back 101

Selection bias

Front 102

Given disease; how many have a positive test

Back 102

sensitivity

Front 103

Given no disease; how many have negative test

Back 103

Specificity

Front 104

Given a positive test; how many have disease

Back 104

Positive predictive value

Front 105

Given a negative test; how many do not have disease

Back 105

Negative Predictive value

Front 106

Whats the reason that most rare diseases are not screenied for?

Back 106

If prevalence is low, positive predictive value will be also low

Front 107

Yield of positive predictive value and prevalence can be increased by

Back 107

Screening in high risk groups

(Ex. tay Sachs among Jews,

Sickle cell among African Americans)

Front 108

Test that is considered to be the most accurate among all the known tests.

Back 108

Gold-standard

Front 109

Proportion of all subjects who were correctly classified by the test

Back 109

Accuracy

Front 110

The degree to which a measurement represents the true value

Back 110

Accuracy

Front 111

Equation for accuracy

Back 111

(TP + TN) / Total screened

Front 112

Wheter a positive lab test indicates a person truly has the disease

Back 112

Validity

Front 113

A good kappa value that indicates a reliable test and reliable raters, is:

Back 113

At least 75%