Midterm 2 : Week 7,8,9,10 Flashcards

(111 cards)

0
Q

Define a Study

A

A study is a detailed investigation into a specific health topic

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1
Q

Define Epidemiology

A

Epidemiology is the he study of the distribution and determinants of disease in a population and using this study to control the disease

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2
Q

What is a Study in Epidemiological terms?

A

A Study in epidemiological terms is both surveillance and epidemiological research

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3
Q

Define Surveillance

A

Surveillance is the tracking and forecasting of any health event or health determinant through the continuous collection of data & the analysis of the data into a report

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4
Q

Define Passive Surveillance

A

Passive surveillance, is surveillance that issues after a confirmed case or symptom is shown

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5
Q

Define Active Surveillance

A

Active Surveillance is surveillance that is actively searching for data on disease or other health determinants

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6
Q

Define Epidemiological research

A

Epidemiological research is the collection of data on the causes, prevention and treatments of disease

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7
Q

Define Valdity

A

Validity is how well an instrument measures what it claims to measure

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8
Q

Define Precision

A

Precision is how many times a calculated value is the same when the calculations are done again

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9
Q

Define Accuracy

A

Accuracy is how close a value is to it’s true value

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10
Q

What are the 4 general processes of health research?

A
  1. A question 2. Development of a hypothesis 3. Design a study 4. Assessment of the cause-effect relationship
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11
Q

What things might cause the development of a 1. question?

A

A question might develop if something is different, or if something changes

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12
Q

How is a hypothesis developed?

A

We develop a thesis from finding or not finding patterns in preliminary data

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13
Q

What is the purpose of a study?

A

To test the hypothesis and see if further studies should be done

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14
Q

How do we access whether there is a 4. cause-effect relationship or if it’s just an associational relationship?

A

You use look at the bradford hill criteria for causation, example. timeline must be correct; the cause must come before the disease, Coherence; It has to agree with currant logic, Dose-Response relationship; the greater the dose there is the greater affect there should be, Consistency; if the experiment is replicated the results must be consistent

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15
Q

What kinds of factors effect the choice of study?

A

Time,funds, the situation, the issue being studied

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16
Q

What are the key aspects of an experimental study?

A

Random, controlled (there is a control group) and blind (placebo effect is minimized)

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17
Q

Define a Control group

A

The control group is the group that gets the placebo or is not exposed to the variable of interest

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18
Q

Define the Treatment group

A

Receive the treatment, and have almost all the other same variables as the control group

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19
Q

What are the key aspects of an observational study?

A

No control group

No randomization

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20
Q

Why are Observational studies conducted more often then Experimental studies?

A

Observational studies are conducted more often then Experimental studies because it can be immoral or unethical to conduct experimental studies sometimes, for example taking a necessary drug away from someone because they were chosen to be put in the control or exposing someone to something that maybe extremely harmful to them for example if the treatment was crack cocaine. But if the subject is already exposed to the treatment of their own accord we can do a observational study

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21
Q

What should the results of a well designed observational study be similar to?

A

The results of a well designed observational study should be similar to the results of an experimental study if it was done on the subjects

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22
Q

What can self exposure be a consequence of?

A

Self exposure can be a consequence of habit, occupation, emotional or psychological stress, geographical location etc?

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23
Q

What terms do we use in an observational study instead of control and treatment group?

A

We use the terms unexposed and exposed group in an observational study instead of control and treatment group

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24
Define Exposed group
The Exposed group is the group that has the characteristic/variable of interest
25
Define Unexposed group
The Unexposed group is the group that does not have the characteristics/variable of interest but is otherwise similar to the Exposed group
26
Define the Counterfactual Ideal
The Counterfactual Ideal is when control group and treatment group or unexposed and exposed group are exactly the same; there is not change in variables except the variable of interest. The problem with this is time is a variable as well, so even if the subjects went through 6 months of unexposed and then 6 months of exposed the time variable for when they do the test will be different and therefore the affects on them will differ
27
What is the Counterfactual Ideal used for?
the Counterfactual Ideal is used as a goal by epidemiological researchers; the match the control group (unexposed group) as closely as they can to the treatment group (exposed group) [except for the variable of interest, ofcourse] so they are as close as possible to the Counterfactual Ideal
28
Define Crossover study
There will be a control and experimental group and a certain time amount later the people from the control group will become the experimental group and vice versa
29
What is the Gold Standard for medical research?
R.C.T. : Randomized clinical trials
30
What are the key aspects of a R.C.T (Randomized Clinical Trial)?
1. Two or more interventions (exposures) are compared; no intervention can be an intervention 2. Exposure status is assigned randomly; placement of subjects is not controlled by anyone
31
What are the 5 strengths of RCT's?
1. Information is collected starting in the present into the future; not from the past, so memory accuracy is not as big a problem 2. The experiment is controlled 3. Less loss to follow up; RCT's tend not to be long 4. Random assignment reduces risk of error, and bias 5. It's easy to blind subjects and researchers
32
What is the down fall of RCT's (Randomized Clinical Trials)?
They're not always possible; for moral and ethical reasons
33
Define a Cohort Study
A Cohort Study is a study which measures the incidence of disease or another health outcome; starts out with subjects who do not have the disease or health outcome but are at risk for it
34
What are the 5 key points of a Cohort Study?
1. Cohorts are chosen on the basis of whether they've been exposed to a variable which is hypothesized to cause a certain disease of health outcome 2. Usually a large number of people are followed over a long period of time 3. Study can move forward or backward in time; can as about past events or currant events 4. Members of the cohort must be able to develop the disease; men can't be treated for ovarian cancer! 5. Cohorts may be open or closed
35
What are the 3 strengths of a Cohort Study?
1. Cohort studies are good for rare exposures 2. Comprehensive data 3. Can follow multiple outcomes
36
What are the 4 weaknesses of a Cohort Study?
1. Need a large sample size to get a accurate incidence rates 2. Must be over a long period of time 3. Difficult to maintain followup 4. Expensive
37
Define Case-control Study
A Case-control Study is a study in which groups are chosen based on a disease of interest that the subjects already have
38
What are the 3 key features of a Case-control study?
1. Past history of exposure is being examined; memory accuracy is important 2. Usually looks at multiple exposures that are causal 3. Must be able to develop the disease; can't involve women into a study for prostate cancer
39
What are 3 strengths of a Case-control Study?
1. Can be quick 2. Inexpensive 3. good for studying rare diseases 4. looks at many possible causal exposures
40
What is 3 Weakness of a Case-control Study?
1. No control over exposure (high or low) and variables get confusing 2. Difficult to find controls to match cases 3. Observational; NOT Experimental
41
What are the advantages and disadvantages of a Case Report Study and Case Series Study?
An advantage of Case Report and Case Series studies inexpensive, simple, and quick ways to find new clinical issues and come up with hypotheses A disadvantage of Case Report and Case Series studies is that they are retrospective; memory accuracy is vital, it is prone to selection bias, and there is no control
42
What are the Advantages and Disadvantages of Ecological studies?
The Advantages of ecological studies is that they are quick and inexpensive The Disadvantage to ecological studies is that they can't determine a causal relationship because it can't be used to determine a relationship on a individual level, only a group level
43
The Advantages and Disadvantages of Cross Sectional Studies
The Advantages of Cross Sectional Studies is that they're easy to gather data on and assess and are inexpensive The Disadvantages of Cross Sectional Studies is that it can't determine a causal relationship, is susceptible to lurking variables, and depends on memory accuracy
44
Define Statistics
Statistics is a field of study that focusses on the collection, organization, summarization and analysis of data and drawing conclusions about a population from a sample
45
What kinds of factors influence the type of descriptive statistic researchers use?
Type of data, audience, and question
46
How do data summaries help researchers?
The researchers can share their findings with other researchers or use it as a beginning point for research
47
Define Biostatistics
Statistics used by biologists and health researchers
48
Define Data
Numbers or facts
49
Where might health researchers get their data?
Do studies, government organizations, NGO's
50
What is Nominal data?
Categorical; no numbers
51
What is Ordinal data?
Categorical and on a scale
52
What is a Ranked variable?
N's are ranked 1. 4 2. 5 3. 6
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What is a Discreet variable?
Countable, whole numbers
54
What is a Continuous variable?
Can be as fine as the tool used to measure it allows
55
Define a Statistic?
A descriptive measure calculated from sample data
56
Define a Parameter?
A descriptive measure calculated from population data
57
What is Descriptive Epi?
Quick view of data; map etc
58
What factors can cause change in disease rates over time?
- Good Diagnostic equip: makes cases appear more - Diagnostic criteria: It switches often and geography determines this - More people survive; people with illness appears higher
59
Define a Disease Cluster?
Events that occur in a specific area that is unlikely to be coincidence
60
What might cause a Disease Cluster?
Leak,Poison, Occupation, New disease, Food or Water source
61
Define Zoonotic disease
Non-human animals to humans
62
Define a Epidemic
Higher than expected disease in a defined area; not across continents
63
Define a Pandemic
In many areas, across continents
64
Define a Hypothesis
A tentative explanation; educated guess
65
What are 5 things we can do to develop a hypothesis?
1. We compare similar populations and look for differences 2. We compare different populations and look for similarities 3. Look for a dose response relationship between populations 4. Look at different factors that are said to cause disease 5. Compare known diseases to an unknown disease
66
Define a Population
A population is a group that shares a certain characteristic; define by the researcher
67
What are some common characteristics that define a population?
Age, Bio-Sex, Religion, Socio-economic status, Geography, Ethnicity etc
68
What characteristics may influence who attends a certain medical facility?
Socio-economic status via geography, geography, specialization of the hospital, etc
69
What must we think about when comparing populations?
That the populations are as similar as possible, or we take differences into consideration when comparing them
70
What is a Fixed/Closed Population?
Membership is permanent; you can't join or leave, sample size will stay the same
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What is a Dynamic/Open Population?
Membership is not permanent; you can join or leave; no set sample size
72
What is a Steady State Population?
Equilibrium; when goes another comes, there is a steady rate of people coming and going
73
Why is it difficult to make valid comparisons between populations from different time periods?
Age, Socio-economic status, political circumstances, war, disease, social and cultural attitudes, treatments available, etc.
74
What are the 3 common types of calculations used when describing and comparing disease frequencies?
Ratios, Proportions, and Rates
75
What is Incidence?
Incidence is the risk of getting a disease; only look at cases of new disease
76
What are 3 things to remember when talking about incidence?
1. We're looking at new cases of disease 2. Population being studied must be able to develop the disease 3. Time MUST be explicitly mentioned
77
Define Cumulative Incidence
Cumulative incidence is the # of new cases of disease in a defined population over a specific time period
78
Cumulative Incidence is usually multiplied by what?
Cumulative incidence is often multiplied by 1000
79
Cumulative Incidence can only be calculated for what kind of population?
Cumulative incidence can only be calculated for a closed population
80
Define Loss to follow-up
Loss of our capacity to track/study a participant
81
Define Incidence Rate
of new cases in some defined population measure in person time (person/years)
82
What is the difference between Cumulative Incidence and Incidence Rate?
Cumulative Incidence is measured for a specific time, where as Incidence rate is measured for a specific person time
83
Define Person time
The amount of time that a person is being tracked/exposed/studied
84
What is something important to know about person time?
A person are part of the study only until they develop the disease of interest
85
What is the advantage of using person time?
Even if you lose people, because of a open population; you can still use the data you collect
86
What kind of population is best for Incidence Rate?
Incidence rate is the best calculation for a open population
87
What is the equation for calculating Incidence Rate?
of cases of new disease/ # total population person days
88
Define Prevalence
The total # of people who have a certain disease in a defined population over time
89
What are the 2 types of prevalences?
1. Point Prevalence: Snapshot; prevalence at a moment in time; on July 1st 2. Period Prevalence: Over a time; from January 2 to February 2
90
What are the 13 commonly used Mortality Rates?
1. Crude Mortality rate: total # of deaths in a defined population/some defined time, measured in 100,000 2. Proportional Mortality Rates: Total # of deaths/Total # of deaths expected 3. Case Fatality Rates: Total # of people who died from a specific disease/ Total population at risk, per 100,000 4. Age Specific Mortality Rate: Total # of people a specific age who died/ Total number of people in that age category 5. Maternal Mortality Rate: # of women who die from complications during birth/100,000 live births 6. Infant Mortality Rate: # of infants that die under the age of 1/ 100,000 live births 7. Crude Birth Rate: Total 3 of live births in a defined population/ some defined time period, measured in 100,000 8. Fertility Rate: # of births per woman in her child bearing years in a particular time period 9. Age Specific Fertility Rate: # of births to women in a particular age category in a particular time period 10. Attack rate: Frequency of morbidity 11. # or percentage of people who are alive for a defined time period after treatment 12. The average time a person would have lived if they had not died prematurely 13. Disability Adjusted Life Year: Number of years lost due to ill health or disability
91
Define Risk
The chance of developing a disease
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Define Effect Measure/Measure of Effect/Measure of Association
A single value that estimates the association between the exposure/characteristic and developing a disease
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What are effect measures usually?
Effect measures are usually either a absolute difference or a ratio
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What is Crude Data?
Raw data that's untouched and unadjusted
95
What is Adjusted/Standardized data?
Data that has been adjusted/modified to remove any differences between the populations characteristics
96
Define Lurking Variable
Lurking variables must be connected to the variable and the outcome but shape the outcome in a way that the variable doesn't
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What is one way of removing the influence of lurking variables?
Standardization, Collecting data on the lurking data as well
98
What is a major lurking variable?
Age is a major lurking varaible
99
What are the 3 types of absolute comparisons?
1. Cumulative incidence differences 2. Incidence rate differences 3. Prevalence differences
100
What is the equation for Risk Difference/Attributable Risk?
RD = Re - Ru ``` (-value) = unexposed group at higher risk; variable has protective factors (+value) = exposed group is at higher risk; variable has harmful factors ```
101
For what kinds of diseases can risk be eliminated by eliminating the variables with attributable risk?
Infectious diseases
102
What is the equation for the proportion of risk due to exposure?
Re-Ru/Re 37.9% of the CHD in smokers could be eliminated if they stopped smoking is how to interpret it
103
What does Population Risk Difference mean?
Population Risk Difference is overall risk for a population
104
What is equation for calculating Population Risk Difference?
PRD = Rtotal population - Runexposed group
105
What is the equation for Population Impact?
[(Risk for exposed)*proportion of exposed population] + [(risk for non-exposed)*proportion of non-exposed populations)] Ex: [(28/1000)*0.44)]+[(17.4/1000)*0.56)]
106
What are the 2 types of Relative Risk?
1. Relative cumulative incidence ratio | 2. Incidence rate ratio/prevalence ratio
107
What is the Equation for Relative Risk?
The equation for relative risk is RR = Re/Ru
108
If exposure increased risk..
The value would be greater than 1
109
If exposure decreased risk..
It would be less than 1
110
Relative risk is not a good measurement for what?
For case-control studies