EBH Flashcards

1
Q

What is the James Lind Alliance and what is it used for?

A
  • non profit organization

- used for identifying research priorities (prioritizes the top 10 unanswered questions)

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2
Q

How is the target population derived?

A

from eligibility criteria

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3
Q

How is the accessible population derived?

A

from the target population + limited by TIME and GEOGRAPHY

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4
Q

The accessible population is a subset of the target population. How is the accessible population derived?

A

Limited by TIME and GEOGRAPHY

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5
Q

What are the 2 MAIN subgroups of studies?

A
  1. Intervention

2. Observational`

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6
Q

What are the 2 main subtypes of Observational Studies?

A
  1. Analytic (has comparison group)

2. Descriptive (no comparison group)

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7
Q

What are the 2 types of descriptive studies?

A
  1. Cohort Study

2. Cross-Sectional Study

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8
Q

List the 4 different types of measurement scales

A
  1. Numeric
  2. Ordinal
  3. Nominal
  4. Dichotomous
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9
Q

What is an ordinal scale?

A

It is used to measure a relative quantity (e.g. a patient’s severity of pain or quality of life)

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10
Q

List 3 examples of ordinal scales that are used to measure PAIN

A
  1. Verbal Descriptor Scale
  2. Wong-Baker Facial Grimace Scale
  3. Activity Tolerance Scale
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11
Q

List 2 types of graphs that frequencies (frequency data) can be presented on

A
  1. Stacked Histogram

2. Bar Chart/Graph

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12
Q

Dot plots can be used to display data if 2 conditions are met. What are the 2 conditions?

A
  1. Continous scale
  2. Small amounts of data

If there are larger data sets, there will be too many dots and so we rely more on summaries

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13
Q

What is another name for a quantile?

A

a percentile

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14
Q

What is the percentile of the median?

A

50th percentile

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15
Q

List 2 summary measures that are ROBUST

A
  1. Median

2. Interquartile Range

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16
Q

List 2 summary measures that are NOT ROBUST

A
  1. Mean

2. Range

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17
Q

What is the definition of variance?

A

The average of the squared differences from the mean

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18
Q

How is standard deviation calculated?

A

it is the square root of the variance

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19
Q

What is the definition of skewness?

A

an excess of low or high values

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20
Q

What is the definition of Point Prevalence?

A

the proportion of persons w/ a particular disease or attribute on a SPECIFIC date

e.g. how many people have the disease?

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21
Q

What is the formula for point prevalence? (i.e. how do you calculate the point prevalence?)

A

(Number of Cases) / (Total Number of People at Risk at that Point in Time)

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22
Q

What is the definition of Period Prevalence?

A

the proportion of persons w/ a particular disease or attribute within a SPECIFIED TIME PERIOD

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23
Q

What is the formula for period prevalence? (i.e. how do you calculate the period prevalence?)

A

(Number of Cases at Any Time in the Study Period) / (Total Number of People at Risk at the Start of the Study Period)

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24
Q

What is the prevalence useful for? (what is it used to determine?)

A
  • tells us the burden of disease

- useful for measuring the demand for health services

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25
Q

How is the cumulative incidence calculated?

A

(# of new cases) / (total # of people at risk)

[this is all during a designated time period]

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26
Q

What is the advantage and disadvantage of cumulative incidence?

A

Advantage: tells you how many patients will emerge over time

Disadvantage: not useful for conditions that may happen repeatedly to the same person

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27
Q

What is the incidence density? How is it calculated?

A

Incidence Density: incidence rate; tells us the rate of events per person-time (usually per person-year)

= (# of new cases) / (total person-time at risk)

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28
Q

What is the main advantage of calculating incidence density rather than cumulative incidence?

A

it is useful for diseases that recur

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29
Q

Do short-lasting diseases have a high or low prevalence?

A

low prevalences (e.g. the common cold)

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30
Q

Do long-lasting diseases have a high or low prevalence?

A

high prevalences (e.g. angina, HIV/AIDS)

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31
Q

List 2 values that can be used to evaluate a SCREENING test

A
  1. Sensitivity

2. Specificity

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32
Q

Sensitivity can be used to evaluate screening tests. What is sensitivity?

A

it is the percentage of people WITH the problem who are correctly identified by the test

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33
Q

Specificity can be used to evaluate screenings tests. What is specificity?

A

it is the percentage of people WITHOUT the disease who are correctly identified by the test

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34
Q

How is sensitivity calculated?

A

Sensitivity = (True Positive) / (All People with the Disease)

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35
Q

How is specificity calculated?

A

Specificity = (True Negative) / (All People without the Disease)

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36
Q

List 2 values that can be used to evaluate a DIAGNOSTIC test

A
  1. Positive Predictive Value

2. Negative Predictive Value

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37
Q

What is the positive predictive value and how is it calculated?

A

PPV: the percentage of all positive tests that are true positive tests

PPV = True Positive / All Positive Tests

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38
Q

What is the negative predictive value and how is it calculated?

A

NPV: the perventage of all negative tests that are true negative tests

NPV = True Negative / All Negative Tests

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39
Q

What is another name for the Relative Risk?

A

Risk Ratio

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40
Q

What is the general formula for calculating the Risk Ratio?

A

RR = (Incidence of Disease in EXPOSED Group) / (Incidence of Disease in UNEXPOSED Group)

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41
Q

How is the Incidence Rate Ratio calculated? (what is the formula?)

A

IRR = (Incidence Density in EXPOSED Group) / (Incidence Density in UNEXPOSED Group)

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42
Q

To calculate the relative risk, you need to know the….

A

Incidence

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43
Q

To calculate the relative risk, you need to know the incidence and this cannot be determined in which type of studies?

A

Case-Control Studies

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44
Q

What is the purpose of the Odds Ratio?

A
  • it measures the association b/w exposure and outcome
  • usually done when the incidence cannot be calculated
  • it is a good approximation of the relative risk
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45
Q

For which studies (predominantly), is the prevalence ratio calculated for?

A

Cross-Sectional Studies

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46
Q

What is the formula for the Prevalence Ratio?

A

PR = (prevalence of outcome in EXPOSED group) / (prevalence of outcome in UNEXPOSED group)

predominantly used for Cross-Sectional Studies

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47
Q

What is the formula for the Relative Risk Reduction?

A

1 - Relative Risk

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48
Q

What is the Risk Difference (definition)?

A

Risk Difference: the difference b/w the risk of an outcome in the exposed group vs the unexposed group

  • can be calculated using either the cumulative incidence or incidence density
  • unit = PER PERSON YEARS
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49
Q

How can the Risk Difference be calculated?

A

Risk Difference = (Incidence in EXPOSED Group) - (Incidence in UNEXPOSED Group)

can be calculated with either cumulative incidence or incidence density

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50
Q

What unit is used for Risk Difference?

A

per person years

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51
Q

How can the Number Needed to Treat (NNT) be calculated? (most likely/common method?)

A

NNT = 1 / (risk difference)

Note: for NNT, always round up

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52
Q

The relative risk (risk ratios) can be calculated for what type(s) of studies?

A
  1. Cohort Studies

2. Intervention Studies (e.g. RCT)

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53
Q

What measure of exposure effect (e.g ratio) can be calculated from a CASE-CONTROL study?

A

Odds Ratio

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54
Q

What are the 2 types of error?

A
  1. Random Error = by chance

2. Systematic Error = bias

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55
Q

What is precision? (give the definition in regards to random error)

A

Precision is the lack of random error (therefore values fall within a narrow range of values)

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56
Q

Does a smaller or larger sample size reduce the random error?

A

A larger sample size reduces the random error and gives you a more PRECISE estimate

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57
Q

To get an ACCURATE estimate of values, what is required of the sample population?

A

the sample should be REPRESENTATIVE

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58
Q

List the 2 types of error that can arise during the selection of participants in a study

A
  1. Sampling Error - random error simply due to chance

2. Selection Bias - arising from a non-representative sampling method

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59
Q

What type of error is sampling error?

A

Random Error (due to chance)

60
Q

List 2 types of error that can arise when using instruments for measurement in studies

A
  1. Inaccuracy - Bias/Systematic Error

2. Poor Reliability - mainly due to Random Error

61
Q

What is validity? (definition)

A

it is the capacity of a test, instrument or other to give a TRUE RESULT

62
Q

What is reliability? (definition)

A

it is when repeated measurements give the same or similar values

63
Q

What is the type of error that may arise when there are MULTIPLE observers recording measurements in a study?

A

Systematic Error - Bias

64
Q

What type of error is present if there is inconsistencies in values measured by the SAME observer?

A

most likely Random Error (chance)

65
Q

To minimize random error, what should be done?

A

Increase the number of participants or the amount of measurements

66
Q

To minimize bias, what should be done?

A
  • representative sampling

- use of valid measurement instruments and techniques

67
Q

List the 5 different types of probability sampling methods

A
  1. Simple
  2. Stratified
  3. Cluster
  4. Multistage
  5. Systematic
68
Q

List the 2 different types of non-probability sampling methods

A
  1. Convenience

2. Snowball

69
Q

What is a Sampling Frame? (definition)

A

it is an accurate list of all the people in the population of interest (e.g. including traits like age, sex, contact details)

70
Q

What is Simple Probability Sampling?

A

when individuals are randomly selected from the population

71
Q

What is Stratified Probability Sampling?

A

when individuals are organized into “strata” (according to characteristics) then randomly selected

72
Q

What is Multistage Random Sampling?

A

random sampling that is carried out in stages

e.g. simple random sampling to select random SS schools, then randomly select 50% of children from each school

73
Q

What is Systematic Sampling?

A

is the selection of individuals based off of a set system/plan

e.g. selecting every 5th member of the population

74
Q

What is Convenience Sampling?

A

no structure to identifying people

e.g. asking everyone waiting in a waiting room to take part

75
Q

What is Snowball Sampling?

A

finding people in the population who can use their network and contacts to find other people

76
Q

What is Statistical Inference? (definition)

A

it is when the sample is used to make inferences about the population

(small group of people used to make inferences about the larger group)

77
Q

What is the Null Hypothesis (H0) and Alternative Hypothesis (H1)? (definitions)

A

Null Hypothesis: a claim of no difference or no association; the probability that the pattern in the data arose by CHANCE

Alternative Hypothesis: a claim of a difference or an association; the probability that the pattern in the data did NOT arise by chance

78
Q

What test can be done to see:

How likely it is that the difference between the MEANS of 2 groups arose by chance?

A

t-test

79
Q

What test can be done to see:

How likely it is that the VARIATION between the MEANS of a number of groups arose by chance?

A

Analysis of Variance (ANOVA)

80
Q

What test can be done to see:

How likely it is that the association between the rows and columns of a table arose by chance (qualitative variables)?

A

Chi-squared test (if sparse data, Fisher’s exact test)

81
Q

What test can be done to see:

How likely it is that the difference in ordinal response data of 2 groups arose by chance?

A

Mann-Whitney test

82
Q

What test can be done to see:

How likely it is that the differences in survival between several groups arose by chance?

A

Logrank test, Cox regression (Kaplan-Meier used to graph data)

83
Q

If a regression coefficient is 0, what does this mean in regards to null and alternative hypothesis?

A

The null hypothesis can be accepted as there is no relationship/association

84
Q

If a regression coefficient is NOT 0, what does this mean in regards to the null and alternative hypothesis?

A

The alternative hypothesis is accepted (the null hypothesis is rejected) as a relationship exists

85
Q

List 3 factors that affect the range/width of a confidence interval

A
  1. Sample Size - a larger sample will lead to a better estimate
  2. Variability - greater levels of variance yields larger confidence intervals (more uncertainty)
  3. Degree of Confidence - the greater the confidence, the wider the interval
86
Q

If the sample size is larger, what will happen to the confidence interval?

A

It will get narrower/smaller

Big samples give more precise measurements (less uncertainty)

87
Q

If the sample size is smaller, what will happen to the confidence interval?

A

It will get larger

Small samples give less precise measurements (more uncertainty)

88
Q

What is the general formula for calculating confidence intervals?

A

Size of CI = (variability of thing being measured) / (amount of measurements made)

89
Q

List 2 measures of exposure effect that can be calculated from cross-sectional studies

A
  1. Prevalence Ratio

2. Odds Ratio

90
Q

Why can’t the relative risks be calculated in cross-sectional studies?

A

RR needs the incidence and you are not looking at new cases in cross-sectional studies

91
Q

What does a Pearson’s Correlation Coefficient of 0 mean?

A

there is no LINEAR association b/w the 2 variables - however, it doesn’t mean that they are not related, just that they’re not linearly related

92
Q

What is confounding? (definition)

A

there is an apparent relationship between the exposure and outcome, but this is due to a third variable

93
Q

List some of the limitations of cross-sectional studies

A
  • prone to bias
  • results may be due to confounding
  • difficult to establish causality
94
Q

What is the ecological fallacy?

A
  • for ecological studies
  • these studies use aggregate (grouped) data and so, they give you information on the group, but cannot be applied to individuals
  • the associations seen b/w aggregated data does NOT exist at the individual level
95
Q

List the 3 components of a cohort study

A
  1. Follows a defined group of participants
  2. Over a period of time
  3. Records the incidence of events of interest
96
Q

What is a population cohort study?

A

They follow up population groups to document the incidence of diseases (and try to find the associated risk factors)

97
Q

What is a clinical cohort study?

A

They follow up patient groups to document the natural history of a disease

98
Q

What is Survival Time and what type of studies are they used for? (definition)

A

Survival Time: the time until the event of interest (outcome) occurs

used in cohort studies to account for variable follow-up

99
Q

What are the 2 types of cohort studies?

A
  1. Population Cohorts

2. Clinical Cohorts

100
Q

List some of the strengths of cohort studies

A
  • can study multiple different endpoints/outcomes
  • can record incidence
  • less biased
  • external validity
101
Q

List 2 of the main disadvantages of cohort studies

A
  1. Impractical for diseases with a LONG pre-clinical phase

2. Impractical for RARE diseases (e.g. rare outcomes)

102
Q

(Statistical) power is the probability… (definition)

A

that we reject the null hypothesis when its FALSE

103
Q

Case control studies are not suitable when the exposure is…

A

RARE

104
Q

List some of the advantages of case control studies

A
  • useful for rare diseases
  • useful for diseases with long latent periods
  • cheap, quick
  • can study multiple exposures
105
Q

List 4 sources of error in case control studies

A
  1. Selection Bias (e.g. hospital controls)
  2. Observer Bias (aka Interviewer Bias)
  3. Recall Bias
  4. Confounding
106
Q

What can and cannot be calculated in a case-control study?

  • prevalence
  • incidence
  • relative risk
  • odds ratio
A

CANNOT calculate:

  • prevalence
  • incidence
  • relative risk

CAN calculate:
- Odds Ratio

107
Q

What is Simpson’s Paradox?

A
  • a possible effect of CONFOUNDING

- it reverses the direction of the association (makes a positive one negative and vice versa)

108
Q

Why may a multivariable regression be used?

A
  • to deal with CONFOUNDING

- it adjusts the estimated effect of an exposure on an outcome for the effect of other potentially confounding factors

109
Q

What are Preclinical Studies and what occurs in them?

A
  • in vitro and in vivo (animal) studies

- assessment of pharmacology and toxicity

110
Q

What are Phase 0 Trials and what occurs in them?

A
  • short duration
  • < 15 volunteers
  • ‘microdosing’
  • initial eval. of pharmacokinetics
111
Q

What are Phase 1 Trials and what occurs in them?

A
  • healthy volunteers
  • 20 to 100 ppl
  • assesses drug metabolism, bioavailability, toxicity
112
Q

What are Phase 2 Trials and what occurs in them?

A
  • patients
  • 50 to 300 ppl
  • measures effectiveness
  • identifies side effects

2a) determines clinical efficacy
2b) determines optimal (therapeutic) dose

113
Q

What is determined in Phase 2a of a clinical study?

A

the clinical efficacy

114
Q

What is determined in Phase 2b of a clinical study?

A

the optimal (therapeutic) dose

115
Q

What are Phase 3 Trials and what occurs in them?

A
  • large patient groups (300 - 3000)
  • longer duration
  • definitive assessment of efficacy
116
Q

*List the 4 methodological features of a clinic trial?

A
  1. Randomized
  2. Controlled
  3. Blinded
  4. Intention to Treat Analysis
117
Q

What is the Hawthorne Effect and how is it compensated for?

A

Hawthorne Effect: individuals modify their behaviour in response to the awareness of being observed

  • patients don’t know what treatment they are given in clinical trials to reduce this effect
118
Q

What is Intention-to-Treat analysis?

A

All persons randomized to a treatment are counted in the analysis whether or not they complete it or not.

Evaluating the treatment POLICY.

119
Q

What is Per-Protocol Analysis?

A

In clinical trials, this analyzes only those who completed treatment as required (doesn’t include those who are not compliant)

120
Q

What is Equipoise?

A

Equipoise: there must be a genuine uncertainty as to whether the new treatment is better or not; but there should be NO grounds for believing it causes harm

121
Q

What is a Sensitivity Analysis and when may it be done?

A

a sensitivity analysis is when a meta-analysis is re-done with low quality studies removed

122
Q

A meta-analysis can provide misleading results if…

A

the methodological quality is poor

123
Q

A Forest Plot is used to display the results of…

A

a meta-analysis

124
Q

What is Statistical Heterogeneity? (definition)

A

it is the extent to which results from different studies differ from each other in a systematic review
– if the results differ too much, pooling results may be misleading

125
Q

What is the I2 statistic used for?

A

it quantifies the amount of statistical heterogeneity

126
Q

What is Publication Bias and how is it visualized?

A

Publication Bias: when the outcome of a study influences whether or not it will be published or not

Publication bias can be determined by Funnel Plots

127
Q

An asymmetrical funnel plot is evidence of..

A

possible publication bias

128
Q

List the 5 different types of qualitative research designs

A
  1. Ethnography
  2. Narrative Research
  3. Phenomenology
  4. Case Study
  5. Grounded Theory
129
Q

What is Ethnography? (definition)

A

is the study of individual cultures (e.g. social group, geographical, tribal, religious, lifestyle)

a form of qualitative research

130
Q

What is Narrative Research? (definition)

A

the use of a narrative to collect + interpret info about the patient’s experience of illness (e.g. expressive writing interventions - EWI)

a form of qualitative research

131
Q

What is Phenomenology? (definition)

A

it is the meaning of an illness for individuals, through lived experience

a form of qualitative research

132
Q

What is a Case Study? (definition)

A

it is an intensive study about a person, group or a unit - it is aimed to generalize

a form of qualitative research

133
Q

List the 4 forms of sampling in qualitative research

A
  1. Purposive
  2. Convenience
  3. Quota
  4. Snowball
134
Q

What is Data Saturation?

A
  • qualitative research
  • when new data no longer brings in additional insights
  • “informational redundancy”
135
Q

List the 3 types of data collection in qualitative research

A
  1. Interview (unstructured, semi-structured)
  2. Focus Group Discussions
  3. Observational (participant vs. non-participant observer)
136
Q

List the 4 types of qualitative data analysis

A
  1. Content (thematic and framework)
  2. Grounded Theory
  3. Narrative
  4. Conversational & Discourse Analysis
137
Q

What is the COREQ checklist used for?

A

used for reporting qualitative research

138
Q

List the 4 different types of mixed methods designs

A
  1. Convergent Parallel
  2. Explanatory Sequential
  3. Exploratory Sequential
  4. Embedded
139
Q

List some vulnerable groups

A
  • children
  • adults that lack capacity (e.g. dementia, intellectual disability, mental illness)
  • pregnant women
  • elderly
140
Q

What are the 3 requirements to do research on a vulnerable population?

A
  1. Addressing a research need/priority
  2. Can’t be done in a non-vulnerable population
  3. Has to be beneficial to the (vulnerable) group
141
Q

List the 6 types of vulnerability

A
  1. Cognitive
  2. Juridic
  3. Deferential
  4. Medical
  5. Allocational
  6. Infrastructure
142
Q

What is Assent? (definition)

A

is the agreement of someone who is not able to give legal consent (e.g. not of legal age)

143
Q

What is Proxy Consent? (definition)

A

in which people with the legal right to consent delegate that right to another person (e.g. adults who lack capacity)

  • personal representative
  • professional representative
144
Q

What are human challenge trials?

A

when the person is deliberately exposed to an infectious pathogen (usually done in the context of vaccine development)

145
Q

What is the 10/90 Gap?

A

<10% of global health research funding goes to low income countries

but the low income countries is where there are 90% of preventable deaths

146
Q

What are the 3 Rs in animal research?

A
  1. Replacement
  2. Reduction
  3. Refinement