Brainscape's Knowledge GenomeTM

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


See full index

Introduction to Epidemiology > Part I: Fundamentals of Epidemiology > Flashcards

Part I: Fundamentals of Epidemiology Flashcards

1
Q

Epidemiology

A

The study of the distribution and determinants of disease frequency in human populations and application to control health problems

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

Population

A

Group of individuals with a shared characteristic

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

Distribution

A

Analysis of disease patterns according to person, place, and time

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

Objectives of Epidemiology

A
  1. Identify Causes of Disease and risk factors
  2. Determine extent of disease in community
  3. Examine natural history of disease
  4. Evaluate effectivness of interventions and treatments
  5. Input on public policy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Assumptions of Epidemiology

A
  1. Human disease does not occur at random, factors increase or decrease likelihood of disease
  2. Factors can be identified by systematic investigation of populations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Determinants

A

Factors that change a person’s health or make a difference in health (exposures)

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

Endemic

A

disease regularly found among a population in a certain area

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

Epidemic

A

Occurrence of disease in excess of normal expectancy

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

Pandemic

A

Epidemic occuring worldwide, or crossing international boundaries

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

Epidemic Intensity

A

(# of deaths / (Global population + Epidemic duration)

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

Sequence of Epidemiological Investigation

A

–> Suspect Exposure influences disease occurence –> Form hypothesis about exposure-disease association –> Conduct epidemiological studies to measure relationship –> Judge whether association is valid –> Evaluate preventions and treatment –>

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

Descriptive Epidemiology

A

Analysis of dease patterns according to characteristics of person, place, and time

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

Types of Epidemiology

A
  1. Descriptive

2. Analytic / Scientific

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

Roles of Descriptive Epidemiology

A

Describe disease patterns
1. Monitor the publics health
2. Evaluate success of intervention programs
3. Generate hypothesis
Studies: (Case Report, Case Series, Cross-Sectional, Ecologic Study)

Limitation: Cannot Uncover Cause of Disease

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

Roles of Analytical Epidemiology

A

Search for Disease Causes and Preventions
1. Evaluate hypothesis about causes of disease
2. Evaluate success of intervention programs
Studies: (Clinical Trial, Experimental Study, Case-Control, Cohort)

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

Person

A 
Permanent Characteristics
- Age, Sex, Race
Biological Characteristics, 
- Immune status, etc.
Acquired Characteristics 
- Marital Status
Activities
- Occupation, Leisure, Medications, Drugs
Conditions Under which one lives
- SES
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Person: Marriage

A

Protective Hypothesis - Marriage provides an environment conductive to health

Selective Hypothesis - people who marry are healthier than people who never marry

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

Place

A

Benefit: Can help us determine where diseases are occuring and if frequency varies by location

What is it?

  • Residency, site of employment, school district, birthplace, etc.
  • Suburban, Urban, Rural

Can determine if certain communities are at an increased risk of disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Time

A

Occurrences of disease change over time, some are predictable and others are not

Patterns of disease occurence critical for:

  1. Monitoring disease occurrence in a community
  2. Assessing whether ph interrventions made a difference
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

4 Components for Measuring Disease Frequency

A
  1. Population (Which group of people)
  2. Cases of Disease (Numerator)
  3. Size of Population (Denominator)
  4. Time (Be explicit)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Population (Measuring Disease Frequency)

A

Used as the base group from which we count disease frequency

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

Population at Risk

A

Members of the population who are capable of developing the disease being studied

Does not include:

  1. Those who already have the disease
  2. Those who cannot get the disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Source Populations

A

a. Fixed Population: Membership defined on the basis of some event, membership is permanent (e.g. People born in 1982, or survivors of Hiroshima)
b. Dynamic Population: Membership is defined by being in a state or condition, membership is transient (e.g. residents of boston, parents of a teenager)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Numerator of all measures of frequency

A

Cases of disease

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

Disease

A

Any Health outcome (positive or negative)

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

Methods of Disease Assesment

A

Clinical records, diagnostic tests, disease registries, surveillance programs, self reports

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

Denominator for All Measures

A

Size of the population
Full or sample of population
Necessary for comparison of disease across populations

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

Time (Measures of Disease Frequency)

A

Single Point in Time
- At study enrollment, at birth, on a particular date

Interval of Time
- A period of follow-up, from birth to 10 years of age

29
Q

Types of Measures

A

Ratios, Proportions, Rates

30
Q

Count

A

The number of cases of a disease or other health phenomenon being studies

31
Q

Ratio

A

Definition: Division of one number by another

E.g. Ratio = (Observed number of AIDS cases in country A during june) / (Expected number of AIDS cases in country A during June)

32
Q

Proportion

A

Definition: Division of two related numbers, (the numerator is a subset of the denominator)

Often expressed as a percentage

33
Q

Rate

A

Definition: Division of one number by another in which TIME is an intrinsic part of denominator

E.g: Breast cancer incidence rate - number of new cases of breast cancer among 100,000 women over a one year period - 125 cases/100,000 women per year OR 125 cases / 100,000 woman-years

34
Q

Epidemiological Measures of Disease Frequency

A

Three Types:

  1. Prevalence
  2. Cumulative Incidence
  3. Incidence Rate

All measures share three characteristics:
Number of cases (numerator), size of population (denominator), Measure of time

35
Q

Prevalence

A

Definition: Measure presence of EXISTING CASES of a disease in a population during a specified time period

  • A snapshot describing the burden of disease
  • Involves being in a specific state

Denominator includes the TOTAL POPULATION

Proportion of population who have disease

36
Q

Point Prevalence

A

Proportion of population that has the disease at a single point in time

Prevalence = (# of Existing cases at a time point) /
(# in total population at a time point)

Relevant time period does not appear in formula but must be stated using words

37
Q

Incidence

A

Definition: Measures occurrence of new cases of disease in a population during a specified time period
- Involves a TRANSITION from one state to another

Denominator only includes population at risk

  • Exclude those who already have the disease
  • Exclude those who are immune
38
Q

Prevalence vs. Incidence

A

Prevalence Incidence
What:
Existing Disease. New Disease
Why:
1. Asses burden of disease. 1. Etiologic research
2. Use when incidence hard. 2. Evaluation of
preventions/treatments

39
Q

Cumulative Incidence

A
  • Time is described in words
  • Measures occurrence of new cases of disease in a population during a specified time period

Critical Assumption: All people in the population have been followed for the entire time period (NO LTF)

  • CI = (# New cases during time period) / (# in population at risk at start of time period)
40
Q

Incidence Rate

A
  • Time is an intrinsic part of denominator
  • Measures SPEED at which NEW CASES of disease occur in population
  • Does not assume no LTF
  • Time is intrinsic part of denominator
  • Formula: IR = (# New cases during time period) / (Total person-time of observation in population at risk)
  • Units = Person time
41
Q

Attack Ratio (Incidence Measure)

A

Proportion of individuals exposed to infectious agent who become infected over a certain time period

42
Q

Case Fatality Ratio (Incidence Measure)

A

Proportion of individuals with a disease who die of that disease

43
Q

Limitations of Cumulative Incidence

A

No LTF

- Not a perfect measure in a dynamic population or a fixed population that loses members over time

44
Q

Person Time

A

Amount of time each person at risk is under observation

  • Accrued only among persons at risk
  • Accrued only while being followed

Ends when:

  • Person is no longer part of population at risk
  • Observation periods end
45
Q

Converting B/w Prevalence & Incidence Rate

A

Formula: P = IR * D
D = average duration of disease

Assumption

  • Population is in a steady state (In = out)
  • Prevalence is low (<10%)
46
Q

How/Why Do We Compare Measures of Disease Frequency?

A

How: Exposure Status

Why: If disease occurs more often or less often in one group than in the other, then there is an association b/w exposure and disease

47
Q

Comparisons

A

Index group (Exposed) vs. Comparison/Reference Group (Unexposed)

48
Q

Measures of Association

A

Definition: Comparisons of measures of disease frequency

Approaches

  1. Absolute
  2. Relative
49
Q

Absolute Measure

A

Def: Calculate the difference b/w two measures of disease frequency

Types:

  1. Prevalence Difference
  2. Risk Difference
  3. Rate Difference

Formula: RD = R_E - R_U

50
Q

Relative Measure

A

Def: Calculate the ratio of two measures of disease frequency

Types:

  1. Prevalence Ratio
  2. Risk Ratio
  3. Rate Ratio

Formula: RR = R_E / R_U

51
Q

Prevalence Differennce

A

(Based on Prevalence)
Def: Difference in prevalence b/w index and comparison groups

Formula: PD = P_E - P_U (No units)

52
Q

Risk Difference

A

(Based on Cumulative Incidence)
Def: Difference in cumulative incidence b/w index and comparison groups

Formula: RD = CI_E - CI_U (No units)

53
Q

Rate Difference

A

(Based on Incidence Rate)
Def: Difference in incidence rate b/w index and comparison groups

Formula: RD = IR_E - IR_U (Person Time)

54
Q

Interpreting Absolute Measures of Association

A

RD = Difference comparison of prevalence/risk/rate of disease in the exposed group to that of unezposed

Note:

  • Focus on the excess disease in exposed grroup
  • Specify comparison group
  • Specify time period
55
Q

Prevalence Ratio

A

(Based on Prevalence)
Def: Ratio of prevalence b/w index and comparison groups

Formula: PR = P_E / P_U (No units)

56
Q

Risk Ratio

A

(Based on Cumulative Incidence)
Def: Ratio of cumulative incidence b/w index and comparison groups

Formula: RR = CI_E / CI_U (No units)

57
Q

Rate Ratio

A

(Based on Incidence Rate)
Def: Ratio of incidence rate b/w index and comparison groups

Formula: IRR = IR_E / IR_U (No Units)

58
Q

Relative Risk

A

Generic term repersenting all relative measures of association

59
Q

Interpreting Relative Measures of Association

A

Relative Risk = Ratio comparison of prevalence/risk/rate of disease in the exposed to that of the unexposed group

E.g. if RR = 7.45

  • Women with ___ were 7.45 x as likely to have __ over a __ year period compared to women without ___
  • Or had 7.45 x the risk of ___
60
Q

Excess Relative Risk

A

(RR-1) x 100%

Can be negative

61
Q

Risk Difference vs. Relative Risk

A

RD : Repersents measure of public health impact of exposure on disease occurence

RR: Repersents measure of strength or magnitude of the association

62
Q

Association

A
  • An identifiable relationship b/w expsure and disease
  • Indicates that the exposure might cause disease
  • Comparisons of risk or rates yields an association
63
Q

Outbreak Investigation Sequence

A
  1. Confrm
  2. Describe
  3. Determine the Cause
  4. Control
64
Q

Outbreak Investigation Detailed

A
  1. Confirm that there is an outbreak
  2. Formulating case definitions
  3. Conducting case confirmation
  4. Establishing the descriptive epidemiology of the outbreak cases
  5. Generating and testing hypothesis about the causes of the outbreak
  6. Collecting and testing environmental samples
  7. Implementing control measures
  8. Interacting with the press and public to disseminate information
65
Q

Epidemic Curves

A
  • Used to describe outbreaks
  • Plot date or time of illness on x-axis, number of cases on y-axis
  • Tell us: distribution of cases over time, outbreaks magnitude, pattern of spread, time of exposure, shape tells us about mode of transmission
66
Q

Point Source Outbreak

A
  • Persons are exposed over a brief time to the same source
    Number of cases rises rapidly to peak and then falls gradualy
    Most cases within one incubation period
67
Q

Continuous Common Source Outbreak

A
  • Persons exposed to the same source but exposure is prolonged over a period of time
  • # of cases might peak and fall, but all cases do not fall within a single incubation
68
Q

Propogated Outbreak

A
  • There is no common source, outbreak is person to person

- Curve will cycle through progressivley taller peaks that are often one incubation period apart

Introduction to Epidemiology (1 decks)

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