NURS 4540 > Class 5 - Epidemiology > Flashcards

Class 5 - Epidemiology Flashcards

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1
Q

What is epidemiology

A

the science of understanding the causes and distribution of population health so that we may intervene to prevent disease and promote health

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2
Q

Epidemiology study populations in order to…

A
  • clarify clinical and demographic characteristics
  • identify who is at risk for illness
  • provide clues to causes of disease
  • guides preventative measures and interventions
  • monitor health of population
  • identify DOH and disease in communities
  • investigate and evaluate interventions to prevent disease and maintain health
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3
Q

What are the 2 sides of epidemiology

A
  1. descriptive
  2. analytical
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4
Q

What is the outline for descriptive epi studies

A

the who, what, when, and where of the health event
- what: disease, injury, death (clinical - case definition)
- who: age, gender, sociodemographic, occupation
- when: time, seasonality, secular trends
- where: place, neighborhood, city, county, census tract
- distribution: frequency of the event and pattern of the frequency

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5
Q

What is the outline for analytical epi studies

A

determinants of disease
- understand factors that influence the occurrence of health-related event (causes, risk factors, modes of transmission)
- understand the “how” and “why” aspects of the event

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6
Q

Epi Descriptive - describing ‘what’

A

Alerts to new problems:
- look for other cases
- develop new surveillance system
- propose hypothesis

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7
Q

Epi Descriptive - describing ‘what’ clinical info includes

A
  • symptoms/signs (case definition)
  • lab results
  • hospitalization
  • lived or died
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8
Q

Epi Descriptive - describing ‘who’ demographic info includes

A

age, sex, marital status

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9
Q

Epi Descriptive - describing ‘who’ socioeconomic info includes

A
  • education
  • occupation, income
  • place of work or residence (postal codes)
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10
Q

Epi Descriptive - describing ‘where’ outline

A
  • where illness began (home, vacation site)
  • where exposure occurred (education, occupation, income, place of work or residence)
  • source of contamination (farm, unwashed produce)
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11
Q

Epi Descriptive - describing ‘when’ includes

A
  • trends (change over time, long-term trends/secular)
  • patterns (cyclical trends seen over several years/seasonal)
  • epidemics
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12
Q

What is an endemic

A

rate of a disease, injury, or other condition is the rate of occurrence that is usual in a population

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13
Q

What is an epidemic

A

occurs when the rate of a disease, injury, or other condition clearly exceeds the usual level for that condition

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14
Q

What is a pandemic

A

rate of a disease, injury, or other condition is the rate of its occurrence in the geographically widespread population

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15
Q

What is our goal with an epidemiological triad of disease

A

break at least 1 side of the triangle to stop the continuation of disease

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16
Q

What are descriptive epi studies used for

A
  • program planning
  • generating hypotheses
  • suggesting ideas for further study
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17
Q

What are analytical epi studies used for

A

to test for hypotheses about the cause of disease and studying how exposure relates to disease

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18
Q

Types of epi studies

A

descriptive and analytic

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19
Q

Types of descriptive studies

A
  • case report: individual case data
  • case series: individual data on a group of cases
  • incidence study: new cases during a specific time
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20
Q

Types of analytic studies

A

experimental (exposure is randomly assigned) and observational

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21
Q

Analytic studies, types of experimental studies

A
  • clinical trial: randomization at the individual level
  • community trial: randomization at the community level
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22
Q

Analytic studies, types of observational studies

A
  • cohort
  • case-control
  • cross-sectional
  • ecological
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23
Q

What is a cohort study

A

Observe groups of people who do and don’t experience an exposure, to compare how many in each group have the disease

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24
Q

What is a case-control study

A

Compares a group of people who have a disease to a similar group who don’t have a disease, and the investigator records who had exposures of interest

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25
What is a cross-sectional study
Snapshot of a specific period in time, with the aim of finding the same kind of relationships as experimental studies; describes exposure and disease in a population at some point in time
26
What is an ecological study
Compares populations rather than individual, association at the group level do not always mean association at the individual level
27
Data for epidemiological studies commonly come from three categories:
- routinely collected data (census data, vital records, surveillance data) - data collected for other purposes (medical, health department, insurance records) - original data collected for specific epi studies
28
Prevalence =
Incidence X Duration of Disease
29
relationship between prevalence and incidence
incidence (new cases) increase prevalence above baseline. and vice versa
30
Incidence Proportion =
of new cases of disease occurring during a specific period / # of persons at risk of developing the disease during that same period
31
Prevalence Proportion =
of cases of disease occurring during a specific period / # of persons in the population at that same period
32
What does incidence proportion capture
disease onset
33
What does prevalence proportion capture
disease status (present or absent)
34
What increases prevalence
- increase incidence - increase duration of disease - influx of cases - emigration of healthy people - influx of susceptible people - changes in diagnostic criteria - better reporting
35
What decreases prevalence
- decreased incidence - decreased duration - high case fatality rate - influx of healthy people - out-migration of cases - poorer case detection - influx of immune people
36
What are screenings
process of classifying people as to whether they are likely to have a disease
37
what are the 3 levels of prevention to consider
primary, secondary, tertiary
38
what is primary prevention
seeks to prevent new cases of a disease from developing in the population
39
examples of primary prevention
- no smoking campaigns - sunscreen - PrEP
40
what is secondary prevention
seeks to reduce the number of existing cases of a disease
41
examples of secondary prevention
Cancer Screenings - mammography - colonoscopy
42
what is tertiary prevention
seeks to limit the disability resulting from disease and improve functioning
43
examples of tertiary prevention
- cardiac rehab - PT, OT
44
What is the natural history of disease
refers to the progression of the disease process from onset to recovery: - pre-clinical (susceptibility to disease) - clinical (from the preclinical stage to death, disability, or recovery)
45
When are screening tests appropriate
(BEFORE symptoms develop) - disease is an important cause of morbidity and mortality - tx is available - impact of disease can be minimized before symptoms develop - prevalence of preclinical disease is high
46
What makes a good screening test
- easy to admin - results can be easily available (automated lab reporting) - test is inexpensive - test imposes minimal discomfort to the screenee
47
screening tests vs diagnostic tests
Screening - done on asymptomatic, healthy individuals who are encouraged to get screened - the benefit that early tx conveys in terms of prognosis should outweigh the net costs of screening Diagnostic - done on sick people who present with symptoms - pre-test probability of disease is high (high disease prevalence) - often performed after a +ve screening test to establish a definitive diagnosis
48
Define the validity of a test
its ability to distinguish between who has a disease and who does not
49
What are the two components of validity
sensitivity and specificity
50
What is test sensitivity
- The ability to correctly identify individuals who have the disease - is it to identify true positive - a test with high sensitivity will have few false negatives
51
what is test specificity
- the ability to correctly identify individuals who do not have the disease - to call a true negative 'negative' - a test with high specificity has few false positives
52
true positive =
- have disease - positive test
53
false positive =
- no disease - positive test
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true negative =
- no disease - negative test
55
false negative =
- have disease - negative test
56
Sensitivity =
TP/ TP + FN
57
Specificity =
TN / TN + FP
58
What are sensitive tests good for?
ruling disease OUT
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What are specific tests good for?
ruling disease IN
60
What is a positive predictive value?
the percent chance that a positive test result I a true positive (i.e. that a person w/ a positive result actually has the condition)
61
PPV =
TP/ (TP+FP) = TP / (all that tested positive)
62
What is a negative predictive value?
the percent chance that a negative test result is a true negative (i.e. that person w/ a negative result is actually disease free)
63
NPV =
TN/ (TN+FN) = TN / (all that tested negative)
64
why are we concerned about false positive results?
- additional testing, perhaps more invasive - anxiety and distress associated with positive test results - impose additional costs on the individual and the health care system
65
why are we concerned about false negative results?
- may delay tx and lead to poorer prognosis - public health concerns if the disease is transmissible
66
When do we want a test with high sensitivity
if missing a case leads to high penalty, aim is usually to minimize false negatives
67
When do we want a test with high specificity
if subsequent diagnostic testing is particularly expensive or invasive, the aim may be to minimize false positives
NURS 4540
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