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Introduction to Epidemiology > Lecture 15 > Flashcards

Lecture 15 Flashcards

Study Design pt. 1 (55 cards)

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1
Q

what are controlled trials?

A
  • experimental branch of research
  • involves allocation (assignment) of the exposures of interest by the investigators
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2
Q

what are arms?

A

different exposure groups in the trials
- intervention/treatment = exposed
- control = unexposed

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3
Q

source population

A

the group of people from which study participants will be selected

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4
Q

sample population

A

the people who are actually selected from the source population to participate in the study

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5
Q

what are the basic steps in a regular control trial (RCT) ?

A
  1. state the research question
    - state the objective & hypothesis
    - define the exposures and outcomes
  2. design the trial
    - randomization, trial type, and masking
  3. conduct the trial
    - selection of the subjects
    - follow and collect data
  4. analyze and report the data
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6
Q

what is the hypothesis?

A

PICO question
P = population
I = intervention
C = comparison
O = outcome

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7
Q

superiority trials

A

designed to devalue whether or not an intervention is superior at reducing a negative health outcome

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8
Q

margin of clinical significance

A

superior to the control in a way that truly makes a difference in clinical practice

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9
Q

non-inferiority trials

A

designed to evaluate whether an intervention is at least as good at reducing the frequency of negative health outcomes when compared to the control

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10
Q

non-inferiority margin

A

a margin within which the intervention would still be considered at least as clinical beneficial as the control

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11
Q

equivalence trials

A

designed to evaluate whether the intervention is relatively similar to the control in terms of its effect on the frequency of health outcomes

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12
Q

equivalence margin

A

an interval centered around then null value within which the intervention and control would be considered to have a similar effect

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13
Q

exposure group

A

either preventative or therapeutic

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14
Q

preventative exposure

A

administered to individuals without the health outcome of interest to assess whether the intervention can reduce negative health outcomes relative to the control

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15
Q

therapeutic exposure

A

is given to individuals with the particular health condition to assess whether the intervention can reduce negative health outcomes relative to the control

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16
Q

comparison group (control arm)

A

usually take a placebo

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17
Q

placebo

A

inert or “fake” treatment

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18
Q

placebo effect

A

individuals report benefits derived from the act of simply receiving an intervention, even if the intervention does not have any clinical benefit
- use of a placebo allows investigators to estimate the effect of an intervention above and beyond any benefits derived from the act of simply receiving the intervention (must be ethical)

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19
Q

standard of care

A

treatment used as part of standard clinical practice

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20
Q

randomization

A

primary benefit - exposed and unexposed group that are comparable on all factors except for the exposure status – isolates the effect of the exposure
- attempt to control for all factors that could introduce bias (social class, ethnicity, backdrop, etc)

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21
Q

randomization techniques

A

simple - Esch study participant is randomly assigned to one of the exposure conditions with no prior steps

stratified - trial participants are first stratified based on important possible confounders (age, sex, etc)
- randomization occurs within each group
- this forces a balance in the stratified factors

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22
Q

units of randomization

A

individual - allocated exposure status to each individual study participant

cluster - allocated exposure status to defined groups

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23
Q

parallel trial

Study These Flashcards
A
  • most common
  • each exposure group receives a single exposure at the same time e
24
Q

crossover trial

Study These Flashcards
A

each subject receives both intervention and the control, one after the other
- some participants receive intervention than control, other receive control than intervention (random)

25
washout period
period where individuals receive neither exposure - not possible for all intervention
26
carryover effect
any impact that an exposure might have that extends into the second observation period
27
factorial trial
compares the effect of two+ interventions -- both individually and jointly -- to a control group - used when the PI is interested in how two interventions work separately and together - allow PI's to assess if there's evidence of interaction between the interventions
28
masking
withhold exposure status information from certain groups to ascertainment bias (aka blinding) participants are less likely to: - differentially adhere to study interventions - experience loss to follow up - use supplementary interventions due to knowing their exposure group
29
open-label trials
not always feasible or ethical to blind example) surgical procedures
30
single masked
only one category of individuals is unaware of the exposure assignment - usually the participant but could be the investigator
31
double masked
two categories of individuals are unaware f the exposure assignment - usually investigator (& study team) and participant (common)
32
triple masked
three categories of individuals are unaware of the exposure assignment - participant, investigator, & analysis - common with industry studies
33
allocation concealment
conceals the order in which participants will be assigned to the trial arms until the moment of the assignment in order to maintain randomization
34
measures of frequency & association
following a group of at-risk individuals for NEW cases - measures of frequency = risk or rate - measures of association = risk- & -rate based
35
intervention efficacy & per-protocol analysis
intervention efficacy = the ability of an intervention to prevent or treat a poor health outcome among those who use the intervention ion according to the study protocols per-protocol analysis = measure of association that reflects intervention efficiency and only includes data from individuals with perfect adherence to their assigned trials
36
intervention effectiveness & intention to treat analysis
exposure assignment may differ from the exposure received
37
intervention effectiveness
measure of the ability of an intervention to prevent or treat whatever health outcome either was designed for among people who are randomized to the intervention, whether or not they actually receive the intervention
38
intention to treat
study participants who underwent randomization are analyzed in their respective assigned arms regardless of whether they adhered to their assigned arm - study participants may be misclassified
39
comparing intervention effectiveness and efficacy
efficacy - true etiologic benefit of the intervention effectiveness - may be more conservative, but are likely to reflect what will really be observed
40
pre-clinical phase
no humans - efficacy, toxicity, and pharmacokinetics are studied in vivo or in vitro - determines dose ranges - used to approve human testing - can be waived depending
41
phase 0 (first in humans) (10-15 people)
provide no data of drug safety or efficacy - very small sample size
42
phase 1 (20-100 people)
- larger number of healthy participants - assess safety, side effects, and tolerability - may consist of a range of drug dosages
43
phase 2 (100-300 people)
- enrolls people with condition of interest or at risk - assesses safety and side effects - assesses effectiveness and efficacy - most trials stop here
44
phase 3 (300 - several thousand people)
- focuses on how well drug works, can be multinational - goal is to get approved by FDA - very expensive
45
phase 4 (post-market) >1,000 people
- after FDA approval - assesses long-term outcomes
46
what are some issues with drug trials?
- expensive - time consuming (7-15 years to go from pre-clinical to FDA approved) - - issue because money runs out & new drugs are not made for infections
47
randomization ethics
is it ethical to randomize a group to an exposure? - no because you can force people to endanger their health
48
Equipoise ethics
- none of the treatment should be known to be inferior or superior - - something isn't working, don't keep doing it
49
stopping rules for controlled trials
when to stop trial early: - risks outweigh the benefits - too few outcomes - lack of equipoise
50
placebo control group ethics
- may not be ethical to use a placebo for a control group (i.e. placebo used in hypertension study) - only used if there's no evidence-based standard of care
51
standard of care (SOC) group ethics
- should be the best SOC available worldwide
52
conducting trial sin under severed and protected population (ethics)
- key is informed consent - literacy and coercion should be considered
53
who are the protected and special populations?
- children - pregnant women / fetuses - decisional impaired - long-term facility pt - mental health pt (inpatient) - prisoners - terminally ill
54
strengths of control trials
- temporality - masking to minimize bias - randomizations - study of rare exposures
55
limitations of controlled trials
- loss to follow up (moving, death, loss of interest) - study of rare outcomes - study of outcomes w/ long induction/latency periods - ethical considerations - generalizability

Introduction to Epidemiology (7 decks)

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