Epidemiology And Biostatistics Quiz 2

Front 1

Define: The existing cases of disease at a specific point in time or during a specified period of time.

Back 1

Prevalence

Front 2

What is the numerator of prevalence?

Back 2

Number of cases of disease

Front 3

What is the denominator of prevalence

Back 3

Number in population at a specified time point

Front 4

What are the three types of prevalence?

Back 4

Point, period and lifetime

Front 5

Define: "Snapshot" view of the amount of disease in a population at a single point in time

Back 5

Point prevalence

Front 6

Define: Amount of disease in a population during a specified period of time

Back 6

Period prevalence

Front 7

point prevalence (at interval beginning) + incidence (new cases) = ________________

Back 7

Period prevalence

Front 8

Define: Perviod prevalence rate in which the period studeid is the whole of the subject's life

Back 8

Lifetime prevalence

Front 9

True/False: Point prevalence includes dead patients in the denominator.

Back 9

False. They are removed from the population

Front 10

What are the three uses of prevalence?

Back 10

Asses public health impact of a specific disease on a community; Obtain periodic estimates of disease occurrence to track changes; Plan allocated health resources

Front 11

List three limitations of prevalence.

Back 11

Impact of survivor patients; change in incidence is not accounted for; prevalence does NOT measure risk

Front 12

What type of information is measured in a cohort study?

Back 12

Incidence

Front 13

What type of information is measured in a cross-sectional study?

Back 13

Prevalence

Front 14

How do incidence and prevalence differ in terms of time?

Back 14

Incidence is a period of time; Prevalence is for a period of time

Front 15

What is the relationship between prevalence and incidence?

Back 15

Prevalence = incidence * the average duration of the disease

Front 16

How do incidence and prevalence differ in their denominator?

Back 16

Incidence has all susceptible people present at the beginning of the period; Prevalence has all people examined including cases and noncases

Front 17

How do incidence and prevalence differ in their numerator?

Back 17

Incidence has all new cases occuring during a period of time among a gorup initially free of disease; Prevalence has all cases counted on a single survey\

Front 18

List two assumptions associated with prevalence?

Back 18

Incidence of the disease is constant over time; duration of the disease has been constant over time (steady state)

Front 19

What does the prevalence ratio compare?

Back 19

The prevalence between two populations

Front 20

What are two distinct advantages of cross-sectional design?

Back 20

1. provides good measure of disease prevalence 2. Can be quick, easy and inexpensive

Front 21

What is one distinct disadvantages of cross-sectional design?

Back 21

1. Measurement of disease and exposure status occurs at the same time. 2. Cannot determine disease incidence

Front 22

A cohort study traces from __________ to ______________ as opposed to a case-control study traces from _____________ to _______________.

Back 22

Exposure to Outcome; Outcome to Exposure

Front 23

Why would we use a case-control study instead of a cohort study?

Back 23

More efficient (narrower subject pool); faster (no need to wait from exposure to effect)

Front 24

How are study subjects selected in a case-control study?

Back 24

Subjected selected on the basis of disease status. Presence of disease = case; Absence of disease = control

Front 25

Besides selecting subjects based on disease status what also needs to be done in a case-control study?

Back 25

Exposure history of 'cases' compared to exposure history of 'controls'

Front 26

What are two requirements for the selection of a control group in a case-control study?

Back 26

Free of disease at time of study; must have had opportunity for both exposure and disease

Front 27

What are the two types of biases for a Case-Control studies?

Back 27

Selection, information

Front 28

Define: A type of bias based on how subjects get into the study.

Back 28

Selection bias (Detection, referral, nonresponse, self-selection, inappropriate comparison group)

Front 29

Define: A type of bias based on after selection, exposure data

Back 29

Information bias (recall, interviewer/abstractor, data collection, prevarication)

Front 30

True/False: You calculate risk in a case-control study.

Back 30

False, you estimate risk in a case-control study. You can NOT calculate risk in a case-control study.

Front 31

Can you get incidence from a case-control study?

Back 31

No. You cannot get incidence from a case control study. (This is also why you can't calculate relative risk)