Epidemiology

Question 1

Define epidemiology

Answer 1

a public health discipline basic science which studies the distribution and determinants of disease in populations to control disease and illness and promote health

Question 2

What are the 3 primary groupings in epidemiology?

Answer 2

disease; exposure; population

Question 3

Who is the father of epidemiology?

Answer 3

John Snow

Question 4

In regards to distribution of disease, what is the frequency of disease occurrence?

Answer 4

not only counts but also counts in relation to size of the population

Question 5

What 3 aspects do patterns of disease occurrence encompass?

Answer 5

person; place; time

Question 6

In regards to distribution of disease, Who/where/when = ____ epidemiology

Answer 6

descriptive

Question 7

In regards to determinants of disease, why/how = ____ epidemiology

Answer 7

analytic

Question 8

New occurrences of an outcome or disease is called what?

Answer 8

incidence

Question 9

Existing occurrences of an outcome/disease is called what?

Answer 9

prevalence

note: includes old and new cases, collectively

Question 10

(new cases of the outcome)/(# persons at risk of the outcome) = ?

Answer 10

incidence

note: always subtract out those who already have the disease

Question 11

What is the equation for incidence rate?

Answer 11

new cases/ person time (total net time people were at risk)

Question 12

Occurrence of disease clearly in excess of normal expectancy is called what?

Answer 12

epidemic

Question 13

an epidemic limited to a localized increase in the occurrence of disease is called what?

Answer 13

outbreak

Question 14

define endemic

Answer 14

the constant presence of a disease within a given area or population in excess of normal levels in other areas

Question 15

define pandemic

Answer 15

an epidemic occurring over a very wide area involving a large number of people

Question 16

Explain difference between quantitative and qualitative research design

Answer 16

quantitative = numbers 
qualitative = words

Question 17

Explain difference between interventional and observational methodology

Answer 17

interventional = forced allocation to study groups

observational = no forced allocation to study groups

Question 18

Explain the different phases of an interventional study

Answer 18

pre-clinical: bench research

phase 1: assess safety, small sample (20-80)

phase 2: assess safety and efficacy in diseased population, larger sample (100-300)

phase 3: primary focus is to assess efficacy, even larger sample (1000-3000)

Phase 4: post-marketing, long-term effects in large population

Question 19

Define a single-blind interventional study

Answer 19

study subjects are not informed which intervention they are receiving but clinicians know

Question 20

Define a double-blind interventional study

Answer 20

neither investigator nor study subjects are informed which intervention each subject is receiving

Question 21

Define an open label interventional study

Answer 21

everyone knows everything

Question 22

Inert treatments made to look identical in all ascents to the active treatment is called?

Answer 22

placebo

Question 23

What is a double-dummy treatment?

Answer 23

more than 1 placebo used

Question 24

What is the placebo-effect?

Answer 24

improvement in condition, by power of suggestion & due to the care being provided

Question 25

What is the hawthorne-effect?

Answer 25

desire of study subject to "please" investigators by reporting positive results, regardless of treatment allocation

Question 26

Group allocation in a cohort study is based on what?

Answer 26

exposure

Question 27

Group allocation in a case-control study is based on what?

Answer 27

disease

Question 28

What does a cross-sectional study examine?

Answer 28

the relationship between disease AND exposure

Question 29

What is absolute risk reduction (ARR)?

Answer 29

subtract risks of two groups

Question 30

What is relative risk reduction (RRR)?

Answer 30

ARR / Risk of unexposed

Question 31

What is the number needed to treat?

Answer 31

1 / ARR

Question 32

Interpret RR = 1.53

Answer 32

53% greater risk in the comparator group

Question 33

Interpret RR = 0.73

Answer 33

27% lower risk of the outcome

Question 34

When looking at the CI for ratios, if both values are on the same side of 1.0, is the data significant or not?

Answer 34

always significant

Question 35

How do you test for confounding?

Answer 35

calculate crude RR and then calculate adjusted RR which controls for confounder. if there is a 10-15% difference, confounding is present

Question 36

What is the purpose of controlling for confounding?

Answer 36

to get a more accurate estimate of the true association between exposure and disease

Question 37

In regards to study design, what are three ways you can control confounding?

Answer 37

randomization, restriction, matching

Question 38

In regards to analysis of data, what are 2 ways you can control confounding?

Answer 38

stratification, multivariate analysis

Question 39

A 3rd variable, that when present, modifies the magnitude of effect of an association by varying it within different levels of a 3rd variable is called what?

Answer 39

effect modification

Question 40

How is effect modification different from confounding?

Answer 40

comparing the crude estimate of the measure of association is not the only element used to evaluate the presence of effect modification, stream-specific estimates are compared directly to see if they are different. If the highest layer is 10-15% different than lowest layer, there is effect modification present

Question 41

How do artifactual associations arise?

Answer 41

from significant bias and/or extensive confounding

Question 42

How do non-causal associations occur?

Answer 42

1. disease may cause exposure (RA leading to physical inactivity) 2. disease and exposure are both associated with third factor (confounding)

Question 43

What are Hill's guidelines?

Answer 43

strength, consistency, temporality, biologic gradient, plausibility

Question 44

Define True Positive

Answer 44

test is positive and patient does have disease (A box)

Question 45

Define True Negative

Answer 45

Test is negative and patient does not have disease (D box)

Question 46

Define False Positive

Answer 46

Test is positive but patient does not have disease

Question 47

Define False Negative

Answer 47

Test is negative but patient does have disease

Question 48

Sensitivity and specificity describe accuracy of ___ ___, while PPV and NPV predict accuracy of ____

Answer 48

test result; diagnosis