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Question 1

Difference between modifier and confounder

Answer 1

Modifier is only associated to disease, not risk factor
Confounder is linked to both disease and exposure

Question 2

Case-control studies have what measurement?

Answer 2

Odds ratio (exposure)

Prevalence odds ratio is from cross-sectional study comparing prevalence between two populations

Relative risk is incidence and is measured in cohort studies

Question 3

Number needed to treat

Answer 3

1/ARR
Absolute risk reduction = % event in placebo - % event with treatment

Question 4

When does odds ratio approximate relative risk?

Answer 4

When incidence/outcome is low (RR = (a/a+b)/(c/c+d), a«b and c«d)

Also when cases and controls are representative of the population (with regard to exposure of interest)

Question 5

Attributable risk percent

Answer 5

Excess risk in exposed population that can be attributed to risk factor

ARP = (Risk in exposed - risk in unexposed)/Risk in exposed

or

ARP = (RR - 1)/RR

Question 6

What must be performed after sentinel events?

Answer 6

Root cause analysis

Question 7

What kind of event is wrong-patient error?

Answer 7

Sentinel event

WPE can be improved through interprofessional rounds

Question 8

Admission rate bias

Answer 8

When distortion in risk ratio exists due to hospitals’ different admission rates for certain cases

Question 9

Response bias

Answer 9

When participant purposely gives slanted response for whatever reason (e.g. med student not wanting to admit to smoking)

Question 10

Type I vs II error

Answer 10

Type I (alpha): false positive; significance level
Type II (beta): false negative; power = 1-beta

Question 11

When is informed consent not needed for research?

Answer 11

Minimal risk and no interaction with patients (i.e. secondary analysis of existing data)

However, informed consent is generally needed if it is protected health info (which helps identify the patient)

Question 12

Absolute vs relative difference in a clinical trial with odds ratio of response

Answer 12

Absolute = treatment response rate - control response rate
Relative = (treatment response rate - control response rate)/control response rate

Question 13

What is a measure commonly used in cross-sectional studies?

Answer 13

Prevalence ratio

Question 14

When is hazard ratio used?

Answer 14

Measure of association for time-to-event (survival) outcomes

Commonly used in cohort studies and experimental designs

Question 15

What is a receiver operating characteristic (ROC) curve?

Answer 15

Plot of true-positive rate (sensitivity on y-axis) against false-positive rate (1-specificity on x-axis)

Compare same cut point on two different curves to assess changes in sensitivity and specificity

Question 16

Hawthorne effect

Answer 16

When subjects change their behavior because they are aware they are being studied

Question 17

Per-protocol vs intention-to-treat analysis - what’s the difference?

Answer 17

Per-protocol: excludes dropouts; estimates “true effect” assuming a perfect scenario but overestimates effect in realistic, practical, clinical setting

Intention-to-treat: includes all participants as initially allocated; conservative estimate but reflects “expected effect”

Question 18

Psychological safety

Answer 18

Comfort with taking actions for the purpose of patient safety

Question 19

Change management

Answer 19

Engaging personnel to make initiatives to improve safety

Question 20

Parallel study

Answer 20

One treatment to one group, different to another group; no other variables measured

Question 21

Factorial design study

Answer 21

2+ experimental interventions, within each are 2+ variables studied independently (same ones across the interventions)

Question 22

What are “forcing functions” or “hard stops”?

Answer 22

Physical designs that prohibit incorrect action (e.g. gas containers with different connectors to ensure connection to correct tubing)

Question 23

Calculating vaccine efficacy

Answer 23

VE = (risk in unvaccinated - risk in vaccinated)/risk in unvaccinated

Question 24

Who should perform oversight of data from clinical trial?

Answer 24

Independent data monitoring committee, not IRB

Question 25

Attributable risk (risk difference)

Answer 25

incidence in exposed - incidence in unexposed
or
(RR-1)/RR * 100%

Question 26

Calculate odds ratio

Answer 26

odds that diseased person is exposed/odds that nondiseased person is exposed

OR = ad/bc

Question 27

When does OR approximate RR in a case control study?

Answer 27

When it is a rare disease (low prevalence)

Question 28

What further bias does case control have over cohort (both have selection bias)?

Answer 28

Recall bias

Question 29

Length bias

Answer 29

When a screening test detects a disproportionate number of slowly progressive diseases but misses rapidly progressive ones, leading to overestimation of benefit of screening

Question 30

Fisher’s exact test

Answer 30

Used to assess differences between two categorical variables when the sample size is small

vs Chi square test, which is when sample size is large