Epidemiology

Question 1

Equation for Relative Risk with chart

Answer 1

[A/(A+B)] / [C/(C+D)]

Question 2

What does an RR of 1 signify

Answer 2

Same risk in both groups
no association between exposure and outcome

Question 3

What does an RR > 1 signify?

Answer 3

exposure is a risk factor for developing the condition

Question 4

What does an RR= 0 signify?

Answer 4

exposure is protective against the condition

Question 5

What is the equation for absolute risk reduction?

Answer 5

ARR = [A/(A+B)] - [C /(C+D)]

Question 6

What is the significance of ARR = 0

Answer 6

no association

Question 7

What is the significance of ARR > 0

Answer 7

positive causal relationship between exposure and disease

Question 8

What is the significance of ARR < 0

Answer 8

exposure is protective

Question 9

What is the equation for NNT?

Answer 9

NNT = 1/ARR

Question 10

What is the equation for relative risk reduction

Answer 10

RRR = 1-RR

Question 11

Equation for Odd’s Ratio

Answer 11

OR = (A x D) / (B x C)

Question 12

What type of study can use an odd’s rattio

Answer 12

All

Question 13

What type of study CANNOT calculate a relative risk?

Answer 13

case-control study

Question 14

What is the significance of OR = 1

Answer 14

No association between exposure and disease

Question 15

What is the significance of OR < 1

Answer 15

exposure protects against disease

Question 16

What is the significance of OR > 1

Answer 16

exposure increases chance of disease

Question 17

Calculation for sensitivity

Answer 17

A / (A+C)

Question 18

Calculation for specificity

Answer 18

D / (B+D)

Question 19

Equation for positive predictive value

Answer 19

A / (A+B)

Question 20

Equation for Negative predictive value

Answer 20

D / (C+D)

Question 21

What is the positive predictive value

Answer 21

probability of having the disease if you have a positive test

Question 22

What is the negative predictive value

Answer 22

Probability of not having a disease if you have a negative test

Question 23

Equation for positive likelihood ratio

Answer 23

= sensitivity / (1-specificity)

Question 24

Equation for negative likelihood ratio

Answer 24

= (1-sensitivity) / specificity

Question 25

What are the types of selection bias?

Answer 25

sampling bias recruitment bias volunteer bias indication bias survival bias

Question 26

What are the types of observation bias?

Answer 26

recall bias Hawthorne effect Evaluation bias Loss to follow up Classification errors

Question 27

Types of descriptive studies

Answer 27

Correlation studies Case report/series cross-sectional studies cohort studies

Question 28

Types of analytic studies

Answer 28

Case-control case-crossover cohort randomized control trial

Question 29

Disadvantage of correlation study

Answer 29

unable to determine cause/effect high confounding factors

Question 30

Disadvantages of case report/series

Answer 30

no control group less generalizable can't determine cause/effect association

Question 31

Advantage of cross-sectional studies

Answer 31

evaluates participants individually therefore more nuance re: independent variables

Question 32

Disadvantages of cross-sectional studies

Answer 32

no evaluation of temporality of risk factors cannot evaluate incidence

Question 33

Advantages of case-control studies

Answer 33

**rare diseases exposure occurred a long time ago evaluate multiple variables/exposures good for hypothesis testing identify risk factors related to a condition

Question 34

Disadvantages of case-control studies

Answer 34

can't define incidence selection bias recall bias can't use relative risk

Question 35

What is a case-crossover study?

Answer 35

determine if a transitory exposure increases risk of having a disease in that time of exposure (eg. increased risk of heart attack during intense activity)

Question 36

Advantages of case-crossover studies

Answer 36

reduce interindividual variability because each person is their own control

Question 37

Disadvantage of case-crossover studies

Answer 37

recall bias

Question 38

How is a cohort study done?

Answer 38

Participants chosen based on whether or not they’ve been exposed to a chosen variable then compare incidence of new pathology in the different groups

Question 39

Advantages of cohort studies

Answer 39

better temporal relationship understanding can evaluate rare exposures can study risk factors that would otherwise be unethical can estimate incidence based on exposure less selection bias

Question 40

Disadvantages of cohort studies

Answer 40

longer term and more costly risk of losing patients to follow-up

Question 41

What is a sampling bias?

Answer 41

participants not representative of general populaion

Question 42

What is recruitment bias

Answer 42

recruited participants have certain characteristics related to the disease

Question 43

What is indication bias

Answer 43

exposure studied is part of diagnostic criteria for a disease

Question 44

What is the hawthorne effect

Answer 44

people act differently when observed

Question 45

What is evaluation bias

Answer 45

evaluator is preferentially looking for certain exposures

Question 46

What are the features of a confounding factor?

Answer 46

factor that is associated to the exposure and associated to the issue but the association is independent of the exposure