Brainscape's Knowledge GenomeTM

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


See full index

EPIDEMIOLOGY > 2. MEASURES OF DISEASE FREQUENCY AND STANDARDIZATION > Flashcards

2. MEASURES OF DISEASE FREQUENCY AND STANDARDIZATION Flashcards

1
Q

What is the flow chart structure for epidemiologic measures?

A
  1. Count
  2. Ratio
    a. proportion
    - prevalance
    b. rate
    - Incidence
    - crude
    - specific
    - adjusted
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a Ratio?

A

The value obtained by dividing one quantity by another

The most general form has no specified relationship between the numerator and denominator

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

What epidemiologic measure do rate, proportion, and percentages fall under?

A

Ratios

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

How do you calculate the ratio?

Of 1,000 motorcycle fatalities, 950 victims are men and 50 are women

A

950/50 = 19

19:1 male to female

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

What is a proportion?

A

A measure that states a count relative to the size of the group.

A ratio in which the numerator is part of the denominator

may be expressed as a %

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

What is the usefulness of a proportion?

A

It can demonstrate the magnitude of a problem

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

What is this an example of:

10 dormitory students develop hepatitis. If only 20 students live in the dorm, 50% are ill and if 500 students live in the dorm, only 2% are ill.

A

A proportion

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

How do you calculate the proportion when out of 4,960 boys aged 5 to 14 years, there were 1,150 African-American deaths and 3,810 White deaths

A
  1. A+B or 3,810 + 1,150 = 4,960
  2. A/(A+B) or
    1,150/4,960 x 100 = 23.2%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a rate?

A

A ratio that consists of a numerator and a denominator and in which time forms part of the denominator

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

What contains the following elements?

  • Disease frequency
  • Unit size of population
  • Time period during which an event occurs
A

A rate

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

What are populations at risk?

A

The population at risk is the population that is exposed, for example, the total population in the case of deaths or the legally married population in the case of divorces

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

Does any proportion adjust for group size (or population size)?

A

yes

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

What are measures of disease frequency?

A

Prevalence

Incidence Proportion (risk)

Incidence Rate (incidence density)

Mortality

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

What is prevalence?

A

It is the number of existing cases of a disease or health condition in a population at some designated time

New + old

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

What is the interpretation of prevalence?

A

prevalence provides an indication of the extent of a health problem

like the prevalence of diarrhea at a camp

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

What is the prevalence of diabetes when a random sample of 1,000 individuals from a population demonstrates 52 diabetics and 948 non-diabetics?

A

52/(52+948) = 0.052 or 5.2%

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

What are the uses for prevalence?

A

When describing the burden of a health problem in a population

When estimating the frequency of an exposure

When determining allocation of health resources such as facilities and personnel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the equation for point prevalence?

A 
# of individuals with the condition at a point in time
-----------------------------------------
# of individuals considered at a point in time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is this an example of - during the course of a semester 23 of the 58 students in a class experienced at least one upper respiratory infection

And what is the calculation?

A

Period prevalence because it’s over a certain point in time (a semester)

23/58 = 39.7%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the definition of Incidence?

A

The number of new cases of a disease that occur in a group during a certain time period

only new!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What else can incidence proportion (risk) be called?

A

Cumulative Incidence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is Incidence Proportion (risk)?

A

It describes the rate of development of a disease in a group over a certain time period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the 3 elements to incidence proportions (risk)?

A
  1. Numerator - the # of new cases
  2. Denominator = the population at risk
  3. Time = the period during which the cases occur
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is this an example of - A cohort on individuals at risk for uterine cancer is followed for 5 years during which time 45 subjects develop the disease

A

Incidence proportion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the alternate form of incidence proportion?

A

Attack rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is attack rate used for?

A

for diseases observed in a population for a short time period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Is attack rate a true rate?

A

no, because the time is often uncertain

like a disease outbreak period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the equation for attack rate?

A

sick/sick + well x 100 (during a time period)

29
Q

When is incidence density (rate) used?

A

An incidence measure is used when members of a population or study group are under observation for different lengths of time

30
Q

What is the equation for incidence density (rate)?

A

Total person-time (years) of observation

31
Q

What is incidence density (rate)?

A

a measurement of the rate at which new cases of disease occur in the population at risk during a defined period

ranges from 0 to infinity

32
Q

What is the interrelationship equation between prevalence and incidence?

A

The prevalence (p) of a disease is proportional to the incidence rate (I) times the duration (D) of the disease or P = I x D

33
Q

What is the interrelationship between prevalence and incidence when there is a short duration?

A

If duration of disease is short and incidence is high, prevalence becomes similar to incidence because with short duration cases either recover quickly or are fatal

example: the flu

34
Q

What is the interrelationship between prevalence and incidence when there is a long duration?

A

If duration of disease is long and incidence is low, prevalence increases greatly relative to incidence.

example: HIV/AIDS

35
Q

What is this an example of - from 1973 to 1977, the average annual incidence rate of lung cancer was 45.9 per 100,000 and the average annual prevalence was 23.0 per 100,000.

A

The interrelationship between prevalence and incidence

36
Q

What does mortality measure?

A

it measures the severity of disease in a population. It qualifies the risk of having a relatively shorter life span

37
Q

Why is mortality important given that everyone dies anyway?

A

It is important because it helps determine whether treatment has become more effective over time

Can serve as surrogate for incidence rates of lethal diseases where identifying new cases is difficult

38
Q

How is mortality used?

A

It is used to compare severity across groups and different populations

39
Q

How is mortality rate like incidence?

A

It can be calculated using mid-point of the population of interest in denominator (risk) or with person-years in denominator (true rate)

40
Q

what are some specific mortality rates used to describe differences across population characteristics?

A

cause specific, gender specific, age specific, and etc.

41
Q

What is the equation for specific mortality?

A 
# of deaths with specific... 
--------------------------------------
# of people specific at mid-year
42
Q

What is the equation for proportionate mortality?

A

Total # of deaths from all causes

43
Q

What is Natality?

A

The ratio of the number of births to the size of the population; birth rate

44
Q

What is crude birth rate used for?

A

It is used to project population changes

45
Q

How are crude birth rates affected?

A

by the number and age composition of women of childbearing age

46
Q

What is the equation for crude birth rate?

A

population size at the middle of that period

X

1,000

per 1,000

47
Q

Should you use crude death rates with caution? Why?

A

yes, because observed differences in crude rates may be the result of systematic factor (sex or age distributions) within the population rather than true variation in rates

48
Q

What are specific rates?

A

refers to a particular subgroup of the population defined in terms of race, age, sex, or single cause of death or illness

49
Q

What are adjusted/standardized rates?

A

The summary measures of the rate of morbidity and mortality in a population where statistical procedures have been applied in order to remove the effect of differences in composition of various populations

50
Q

When are direct methods used to adjust rates?

A

the direct method may be used if age-specific death rates in a population to be standardized are known and a suitable standard population is available

51
Q

Why is there a direct standardization method?

A

To remove bias due to age

52
Q

What are the 4 steps to use the direct standardization method?

A
  1. select a reference population
  2. multiply the age-specific disease rates of the comparison population by the age distribution of the reference population
  3. sum the expected # of cases of disease for the comparison population
  4. divide the total expected # of cases of disease for the comparison population by the total number of people in the reference population
53
Q

What is the equation for age adjusted rates using direct standardization?

A

Total reference population

54
Q

When are standardization rates meaningful?

A

they are only meaningful when directly compared to each other

55
Q

Is the choice of the reference population in direct standardization important?

A

yes, should not be abnormal or unnatural

56
Q

When would an indirect method be used?

A

If age-specific death rates of the population for standardization are unknown or unstable

example: the rates to be standardized are based on a small population

57
Q

What is SMR

A

Standardized Mortality Ratio

58
Q

When is SMR used?

A

can be used to evaluate the results of the indirect method

59
Q

What is used to evaluate the indirect method?

A

SMR

60
Q

What is the equation for SMR?

A

expected deaths

x

100

61
Q

What does it indicate when the observed and expected #s are the same in SMR?

A

that observed mortality is not unusual

62
Q

What does 2.0 mean in SMR?

A

that the death rate in the study population is tow times greater than expected

63
Q

What are 3 common disease rates?

A
  1. Crude, or unadjusted
  2. category specific, or stratified
  3. adjusted, or standardized
64
Q

What are crude disease rates?

A

they estimate the actual disease frequency for a population

65
Q

What are category specific disease rates?

A

rates for subgroups of the total population

can provide general characteristics of the frequency of disease in a population, particularly by person, place, and time

66
Q

Are crude rates or category specific rates more reliable?

A

category specific rates because they provide more detailed information about patterns of disease frequency in the population

67
Q

What are the pro’s and con’s to category specific disease rates?

A

pro - can be used for valid comparison of populations

con - can be cumbersome if there is a large # of categories to compare

68
Q

What is one of the most important factors to consider when describing the occurrence of any disease or illness?

A

Age

EPIDEMIOLOGY (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions