Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Epidemiology Final > Measures of Disease Occurrence > Flashcards

Measures of Disease Occurrence Flashcards

1
Q

What is epidemiology concerned with?

A

**presence **of existing health problems

occurence of new health events in population

*** quantification **of there measurments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is meant by measuring disease?

A

in a population , group, subgroup

amount of disease at one point / period of time

changes in amount of disease over time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

why measure disease?

A

1. to know if disease is present in a population and how it is changing in that population

**2. **Compare disease in groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When measuring disease occurene it is important to define?

A

what

who (Study population)

location / place

time period of study

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define **study, source, **and target populations?

A

- Subjects in study

sample from target population)

- population subjects were drawn from

- populations to which results are extrapolated to

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Types of Measure?

A

Count

Proportion

Rate

Ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define **count **and why it is important to disease occurence?

A

**absolute number of animals with particular disease **

all other measures of disease occurance are based on counts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the measurement of proportion?

A

is the count of diseased expressed as a fraction/ percentage of the animals that could be diseased

* most common proportion is prevalence

(# dz) / (study population total) = proportion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is Rate?

A

expression of change in amount of disease in a defined population per unit of time

new occurence / study population within a time period

Example:

 occurence of influenze in 1 year was 3.1 cases per 1000 pigs in the study population

( 3.1 cases / 1000 pigs / year )

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the meaning of risk factor?

A

determinant of disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the most common rates?

A

cumulative incidence

incidence density

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a ratio?

A

fraction where numerator is NOT part of denominator

examples:

  • 6.1 ticks : 1 sheep
  • # diseased : # non diseased

remember ratios use : NOT /

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

​What is the most common proportion?

A

** prevalence**

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Types of prevalence?

Types of incidence?

A

**Point prevalence **

Period prevalence

Cumulative incidence (attack rate)

Incidence density or Incidence rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the concept of prevalence and what does it interpret ?

A

**proportion of study population that is diseased at any one time or specified period of time **

**interprets: **probability of being diagnosed

how frequently to expect condition in practice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is point Prevalence and what does it interpret?

A

proportion of study population that is diseased at single point in time?

**most common measure of prevalence **

interprets: probability of individual in study population is **diseased **at the time of study

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is period prevalence and what does it interpret?

A

proportion of study population that is diseased during specififed period of time

*** includes all cases : **old and new

**interprets: **probability that individual is diseased during period of study

18
Q

What is the concept of incidence and what does it interpret?

A

number of new cases of disease that occur in the study population over time

**rate of occurence **

**interprets: **probability of non diseased inidividual becoming diseased ( risk of becoming dz)

19
Q

The proportion of disease free (susceptible) individuals in population who became diseased during specific period of time?

A

**Cumulative incidence **

20
Q

What does Cumulative incidence interpret and who does it include?

A

the probability (risk) of susceptible individual becoming diseased during study period

include only susceptible dz free at beginning

include only new cases of dz over study period

21
Q

calculate cumulative incidence?

What assumptions do they give us ?

A

New cases of dz / total population at risk

-both during study time period

All individuals in study population are at risk

all individuals assessed at beginning

  • ID and remove old cases

Must follow enitre population from start to finish

22
Q

What is the cumulative incidence in this example?

Producer in St. Kits imports 150 cows from babesia free country. 12 months later, entire herd was tested and 15 cows + for babesia.

A

15 cases per 150 cows

or

10 cases per 100 cows

( 10 % per year )

the risk (probability) of a cow in this herd becoming infected is 10% per year

23
Q

What is the term for a cumulative incidence during an epidemic and what does it interpret?

A

**Attack rate **

probability of becoming dz during course of epidemic

24
Q

Calculation for attack rate?

A

new cases / total population exposed

  • both during epidemic
25
Q

Instantaneous rate of occurence of new cases of disease among non-diseased animals in population?

A

**Incidence Density or ** incidence rate

26
Q

**T/F: **interpretation of incidence density (incidence rate) does **NOT **occur at any individual animal level

A

**TRUE **

27
Q

Calculation for incidence density?

A

**# new cases of disease during study **

————divided————

**sum of length of time during each individual in population is at risk **

expressed as

cases per animal - time at risk

15 cases per 100 cow - months at risk

28
Q

**T/F: **Only incidence density is reported as animal - time at risk?

A

TRUE

29
Q

**T/F: **Period prevalence and cumulative incidence are reported as cases/ animals/ time?

A

TRUE

30
Q

Prevalence vs Incidence ?

A

Prevalence : measure amount of dz in population

  • all cases includes relative to entire population
  • used to estimate probability that animal is dz

Incidence:** measure of rate of disease **

  • only new cases included relative to population at risk
    • there is always a time component
    • Estimate # of cases of dz expected to occur
31
Q

T/F: new case (incidence) can become an old case (prevalent) and remain so til death/ recovery.

  • The longer old cases are dz and alive = high prevalence
  • Prevalence of a disease may increase when incidence is stable but survivial of cases improves
A

TRUE TRUE AND TRUE

32
Q

What increases prevalence?

A

longer dz duration

prolonged without cure

increase new cases

in migrated cases

out migrated healthy animals

imporoved diagnosis

33
Q

What decreased prevalence?

A

short dz duration

high case fatality rate of dz

decrease new cases

in - migrate healthy

out - migrate of cases

improve cure rate

34
Q

Prevalence:

is used for permanent states or chronic conditions

reflects over magnitude of dz

best measure of over burden (cost, resources, …)

A

TRUE

35
Q

Incidence :

  • used for acute aqcuired dz
  • assess causes (risk factors)
  • best measure to assess inc / dcr in dz frequency
A

TRUE

36
Q

probability of becoming diseased?

A

Disease Risk

use incidence as risk measure

cumulative incidence = incidence risk

37
Q

Individual not diseased and is capable of becoming diseased?

A

At risk

38
Q

Risk factors

A

increase rhe probability of becoming diseased

39
Q

Exposure to risk factor?

A

individual has come into contact with risk factor or has risk factor before becoming diseased

40
Q

Prevalence of death in a given time period

A

Mortality rate

of deaths during time/ total population

41
Q

Cause- Speciffic mortality rate

A

mortality rate due to a specific dz or event

of death from dz / total population during same time

42
Q

Case fatality rate

A

proportion of cases that are fatal, within a specfied time following disease onset or diagnosis

of individual cases of dz that die / total # with dz

Epidemiology Final (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions