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S3- Research II > Epidemiologic Risk Measures and Exploratory Research > Flashcards

Epidemiologic Risk Measures and Exploratory Research Flashcards

1
Q

EPIDEMIOLOGIC RISK MEASURES

A

EPIDEMIOLOGIC RISK MEASURES

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2
Q

Epidemiology is:

  • the study of the _________ and ___________ of disease, injury or dysfunction in human populations
  • the method used to find the _______ of health outcomes and diseases in populations (CDC)
  • to identify those who have a specific disorder, _______ and ______ the disorder developed and what ________ are associated with its presence
  • distinguished as a research approach because it mainly focuses on the identification of ____ ______ for disability and disease
A
  • distribution and determinants
  • causes
  • when and where, exposures
  • risk factors
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3
Q

What are descriptive epidemiologic studies and when are they used?

A
  • They are done when little is known about the occurrence or determinant of health conditions
  • They will often provide info that can be used to set priorities for health care planning
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4
Q

Descriptive epidemiologic studies may be presented in what types of studies?

A
  • case reports
  • correlational
  • survey
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5
Q

Descriptive epidemiologic studies are purposed to answer what questions?

A
  • Who experiences this disorder?
  • Where is the frequency of disorder the highest?
  • When does the disorder occur most or least frequently?
  • How high is the disease frequency?
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6
Q

Frequency can be determined using what two measures?

A
  • Prevalence

- Incidence

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7
Q

What is prevalence and the equation for it?

A
  • Prevalence is a proportion reflecting the number of EXISTING CASES of a disorder relative to the total population at a given point in time
  • P = (# existing cases/total population at risk)
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8
Q

Prevalence Example 1:

  • With a national concern on obesity, the National Health Interview Survey in 2000 found that the number of adults with self-reported obesity was 7,058 out of a sample of 32,375. The prevalence of obesity in this population is expressed as?
  • How is this interpreted?
  • Why can prevalence also be called point prevalence in this instance?
A
  • P=7058/32275 = 21.8%
  • There is a 22% probability that any randomly selected individual from this population would be obese.
  • Because the probability reflects the cross-sectional status of the population.
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9
Q

Prevalence Example 2:

  • Data obtained from a random sample of 973 newspaper employees found that the number of individuals categorized as having upper limb musculoskeletal complains after 1 year was 395. The estimate of the prevalence of upper limb musculoskeletal complaints in this population during a 1-year period is?
  • How is this interpreted?
  • Why can prevalence also be called period prevalence in this instance?
A
  • P=395/973 = 40.6%
  • There is a 41% probability that any randomly selected individual from this population would have upper limb musculoskeletal complaints.
  • Because it combines the existing cases with new cases during the period of one year.
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10
Q

What is incidence and what two equations can be used to calculate it?

A
  • Incidence is a proportion reflecting the number of NEW CASES of a disorder relative to the total population at a given period of time.
  • Cumulative incidence (CI) and Incidence rate (IR)
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11
Q

What is the equation for cumulative incidence?

A

CI= (number of new cases during given time period / total population at risk)

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12
Q

What is the equation for incidence rate?

A

IR= (number of new cases during given time period / total person-time)

with person-time = the time periods of observation for all individuals in the population at risk during the study time frame

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13
Q

Why is IR often considered more efficient than CI?

A

It allows for inclusion of all subjects, while CI would only account for those subjects who were available for the entire study period

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14
Q

CI and IR example:

  • In the Nurse’s Health Study, 121,700 female nurses were enrolled in 1976. During the period of 1976 to 1992, investigators identified 3,603 new cases of breast cancer. Of the women originally enrolled, some left the study as a result of death or loss to follow-up at various times during the period, and some developed breast cancer after different amounts of time.
  • Researchers totaled the amount of time each subject was known to be at risk between 1976 and 1992 to obtain the total person-years observed = 1,794,565 person-years of observation.

What is the IR and CI in this example?

A

IR = (3603/1794565) = 0.002 or 2 cases per 1000 person - years

CI = (3603/121700) = 0.029 or 3 cases per 100 people at risk

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15
Q

Incidence measures are often used to describe _______ and _________ rates.

A

birth and mortality

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16
Q

What are exploratory epidemiologic studies and when are they used?

A
  • Exploratory epidemiologic studies are performed to assess the relationship between specific exposures and disease status.
  • They will establish if an association exists and the strength of that association.
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17
Q

When an association exists in an exploratory epidemiologic study, say that the specific exposure represents a ____ _______ for the disease.

A

risk factor

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18
Q

Descriptive epidemiologic studies may be presented in what types of studies?

A
  • case control

- cohort

19
Q
  • In exploratory epidemiologic studies, various ________ are of concern such as _______ practices, ____________ hazards, and ____________ influences.
  • These exposures increase or decrease the likelihood of developing certain disorders or influence the outcome of a disorder.
A
  • exposures

- lifestyle practices, occupational hazards, environmental influences

20
Q

What is RR and what is it used for in exploratory epidemiologic studies?

A
  • Relative Risk
  • Used to assess the likelihood that someone who has been exposed to a risk factor will develop the disease, as compared with one who has not been exposed.
21
Q

What is the equation for RR?

A

RR = (incidence of disease among exposed / incidence of disease among unexposed)

22
Q

Measures of RR are appropriate for use with _______ studies.

A

cohort

23
Q
  • In exploratory epidemiologic studies, a ____ __________ table is used to determine risk.
  • The vertical columns represent the _________ status.
  • The horizontal rows represent the ________ status.
A
  • 2x2 contigency
  • disease
  • exposure
24
Q

In a cohort study, ____________ can be estimated using a ____ _________ table.

A
  • relative risk (RR)

- 2x2 contingency

25
Q

In regards to the contingency table, RR = (__/(__+__))/(__/(__+__))

A

RR= (a/(a+b))/(c/(c+d))

26
Q
  • What does a RR of 1.0 mean?
  • What does a RR >1.0 mean?
  • What does a RR <1.0 mean?
A
  • The exposure presents no excess risk for the outcome.
  • The exposure presents an increased risk.
  • The exposure presents a decreased risk.
27
Q

RR Example:

  • In a cohort study of the risk of hip fracture associated with leisure time physical activity, data were taken from longitudinal studies over six birth cohorts, a total sample of 130 women.
  • Question: Does physical activity reduce the risk of hip fracture in elderly women?
For the contingency table:
a=48
b=50
c=20
d=12
A
  • RR = (48/98)/(20/32) = 0.49/0.63 = .78

- Yes, physical activity reduces the risk of hip fracture in elderly women.

28
Q

In exploratory epidemiologic studies, is RR an appropriate risk measure for case control studies? If not, what is used instead?

A

No, odds ratio (OR) is used

29
Q

What is the difference between a case control and cohort study?

A

Cohort study is concerned with frequency of disease in exposed and non-exposed individuals, the case-control study is concerned with the frequency and amount of exposure in subjects with a specific disease (cases) and people without the disease (controls).

30
Q

What changes with the 2x2 contingency table when using odds ratio for a case-control study as opposed to a RR for cohort study?

A

In a case control study (OR), instead of using Y/N for disease, we use cases/control.

31
Q

What is the equation for odds ratio (OR)?

A

OR= (a/c) / (b/d) = ad/bc

32
Q

In general, ___ is appropriate for cohort studies, while ____ is appropriate for case-control studies.

A
  • RR

- OR

33
Q
  • What does a OR of 1.0 mean?
  • What does a OR >1.0 mean?
  • What does a OR <1.0 mean?
A
  • no excess risk of developing disorder
  • increased risk of developing disorder
  • decreased risk of developing disorder
34
Q

OR Example:

  • A case control study examined the risk for developing plantar fasciitis associated with body mass index (BMI). The researchers assembled a sample of 50 cases and 100 controls. Among those 50 cases, 29 individuals had a BMI over 30 (considered obese); among those 100 controls, 17 subjects had a BMI over 30. The OR for these data is what?
  • What is the interpretation of this odds ratio?
A
  • O𝑅 =(a⁄c)/(b⁄d) = ad/bc = (29∗83)/(21∗17) = 6.74

- The odds of developing plantar fasciitis are almost 7x greater for those who are obese than for those who are not.

35
Q

Summary for Epidemiologic Risk Measures:

  • Epidemiology is the method used to find the causes of health outcomes and diseases in populations to identify those who have a specific disorder, when and where the disorder developed and what _________. are associated with its presence
  • Descriptive epidemiologic studies can be presented as case reports, correlational studies, or survey studies to study the disease frequency by reporting the __________ (P) or __________(CI; IR).
  • Prevalence equation?
  • Cumulative Incidence (CI) equation?
  • Incidence Rate (IR) equation?
  • Exploratory epidemiologic studies can be presented as ________ studies or _____________ study to estimate the risk of an exposure to the development of a disorder by reporting __________ (__) for cohort studies or _________ (__) for case-control studies.
  • Relative Risk equation?
  • Odds Ratio equation?
A
  • exposures
  • prevalence (P) or incidence (CI; IR)
  • P = # of existing cases at given point / total population at risk
  • CI = number of new cases during given time period / total population at risk
  • IR = number of new cases during given time period / total person - time
  • cohort = relative risk (RR)
  • case control = odds ratie (OR)
  • RR = (a/(a+b)) / (c/(c+d))
  • OR = ad/bc
36
Q

EXPLORATORY RESEARCH

A

EXPLORATORY RESEARCH

37
Q

Exploratory research is done to find ____________.

A

relationships

38
Q

Exploratory research collects observational data using designs of _________ or ______-________. It collects data in the manner of __________ or ___________.
It uses either _________ or __________ studies.

A
  • longitudinal or cross-sectional
  • prospective or retrospective
  • cohort or case-control
39
Q

Difference between prospective research and retrospective research?

A

Prospective Research
-Researchers follow subjects as they progress
Retrospective Research
-Data has been collected in the past, often obtained from medical records, databases, or surveys.

40
Q

Difference between cross-sectional and longitudinal research?

A

Longitudinal
-Researchers follow a cohort over time
-Data collected in a time sequence
-Researcher may describe patterns of change
Cross-Sectional
-Researcher studies a stratified group of subjects at one point in time
-Researcher may compare the characteristics of those strata to draw conclusions

41
Q

In a______ study the researcher selects a group of subjects who do not yet have the outcome of interest and follows them to see if they develop the disorder.

A

cohort

42
Q

In a __________ study the researcher looks backward in time to determine if the groups differ with respect to their exposure histories.

A

case-control

43
Q

Summary for Exploratory Research:

  • Exploratory research is conducted to investigate the __________ between exposure and disease status
  • _________ study collects the data in the present and past
  • __________ study collects the data in the present and future
  • _________ study collects the data at one point in time
  • __________ study collects the data in multiple points over time
  • Cross-sectional study is cheap and easy to gather initial data and identify correlations that can then be investigated further in a longitudinal study, so it may be conducted ahead of any longitudinal study
  • Researcher in a _______ study selects a cohort who do not yet have the outcome of interest and follows them to see if they develop the disorder
  • Researcher in a _________ study looks backward in time to determine if the case- and the control- groups differ on their exposure histories
A
  • relationship
  • retrospective
  • prospective
  • cross-sectional
  • longitudinal
  • cohort
  • case control

S3- Research II (14 decks)

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