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Year 3 - Sci Lit Final > 1 - RCT Critical Appraisal 1** > Flashcards

1 - RCT Critical Appraisal 1** Flashcards

1
Q

What is a variable?

A

A factor that can be measured (or un-measured) that has effect on exposure and outcome

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2
Q

Which types of studies are considered observational studies?

A
  • Analytic studies (case control and cohort)

- Descriptive studies (cross sectional)

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3
Q

Describe an observational study

A

Investigators use the data observed in the population to make inference on the relationship between the variables

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4
Q

Describe an experimental study

A

Investigators intervene in the natural hx by actively altering one of the variables and then making inference on the relationship between the variables based on the outcomes

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5
Q

Example of an experimental study

A

RCTs

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6
Q

Examples of comparison groups in an experimental study

A
  • Therapy vs. no therapy
  • Therapy vs. placebo or sham
  • Therapy A vs. therapy B
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7
Q

What is the difference between a randomized clinical trial and a randomized control trial?

A
  • All clinical trials are considered controlled

- Not all controlled trials are considered clinical

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8
Q

What is a randomized clinical trial?

A
  • Trial = experiment
  • Clinical trial = controlled experiment having a clinical event as an outcome measure, done in a clinical setting, and involving persons having a specific disease or health condition
  • Randomized clinical trial = clinical trial in which participants are randomly assigned to separate groups that compare different tx
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9
Q

Why are RCTs the gold standard of study designs?

A

Potential for bias (selection into tx groups) is avoided

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10
Q

What is random allocation?

A
  • All participants have a defined, equal probability of assignment to a particular intervention
  • Allocation not determined by the investigator, clinicians, or participants
  • Not predictable based on a pattern
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11
Q

What is the purpose of random allocation?

A
  • Covariates are distributed equally across the groups at baseline
  • Affects both measured and unmeasured variables
  • Risk of imbalance remains even after properly executed randomization
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12
Q

What can happen when a study isn’t randomized?

A

Can make the tx seem like it is working when it might not be b/c the proportions differ

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13
Q

Benefits of randomization

A
  • Eliminates bias in tx assignment
  • Facilitates blinding (masking) of the identity of tx from investigators, participants, and assessors, including the possible use of a placebo
  • Permits the use of probability theory to express the likelihood that any difference in outcome between tx groups merely indicates chance
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14
Q

What elements of a trial can be randomized?

A
  • Most common = individual patient

- Sometimes groups are randomized (cluster randomization) -> ex: families, schools, towns, hospitals

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15
Q

What are downsides to cluster randomization?

A
  • Worry about contamination

- Need special statistical techniques to cope w/ the loss of independence of the individual units

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16
Q

How is randomization achieved?

A
  • Two steps:
    • Generation of allocation sequence
    • Implementation of allocation (concealment of allocation) **very critical
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17
Q

Describe the types of generation of allocation sequence

A
  • Simple randomization (analogous to a repeated fair coin tossing)
  • Restricted randomization (blocking – done to ensure equal balance of arms throughout all portions of the study)
  • Stratified randomization (individuals identified based on important covariates, ex: sex, age, and then randomization occurs within the strata, intended to ensure good balance of these factors across intervention groups)
  • Dynamic or adaptive methods (not common)
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18
Q

What can not concealed allocation lead to?

A
  • If those making the decision about pt eligibility are aware of the arm of the study to which the pt will be allocated, they may systematically enroll sicker or less sick px to either tx or control groups
  • Study will yield a biased result
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19
Q

What is compliance?

A

Willingness of the participants to carry out the procedures according to the established protocols (adherence)

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20
Q

What is the difference between drop-outs and drop-ins?

A
  • Drop-outs = participants who don’t adhere to the experimental regimen during follow-up
  • Drop-ins = participants who don’t adhere to the control regimen during follow-up
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21
Q

How to deal w/ non-compliance

A
  • Monitor (observe tx directly, count pills, conduct blood or urine tests to confirm compliance)
  • Use “run-in” period
22
Q

Describe a run-in period

A
  • Occurs before randomization
  • Give all patients both tx and then after a period of time, see who complied and who didn’t
  • Take out everyone who were “poor compliers” and randomize the rest
23
Q

What are some classification schemes for RCTs?

A
  • Based on type of interventions being evaluated
  • Based on how participants are exposed to interventions
  • Based on number of participants
  • Based on whether goal is evaluation of superiority vs. equivalence vs. non-inferiority
  • Based on whether investigators and/or participants know which intervention is being studied
24
Q

Describe phase 1 clinical trials

A
  • Test new drug or tx in a small group of people (20-80) for the first time to evaluate safety
  • Determine levels of toxicity, metabolism, pharmacological effect, and safe dosage range
  • Identify side effects
25
Q

Describe phase 2 clinical trials

A

Drug or tx is given to a larger group of people (100-300) for efficacy and to further evaluate its safety

26
Q

Describe phase 3 clinical trials

A

Drug or tx is given to a large group of people (1000-3000) to confirm its effectiveness, compare it to commonly used tx, and monitor side effects

27
Q

Describe phase 4 clinical trials

A

Drug or tx is monitored to gather more info on risks, benefits, and optimal use

28
Q

What is the difference between efficacy and effectiveness?

A
  • Efficacy = does the intervention work in the people who actually receive it? (tend to be explanatory)
  • Effectiveness = how does the intervention work in those offered it (tend to be pragmatic)
29
Q

What is the difference between superiority and equivalence trials?

A
  • Superiority = intended to determine if new tx is different from (better than) placebo or existing tx; null hypothesis = no difference between tx
  • Equivalence = intended to determine that new tx is no worse than active control; null hypothesis = difference between tx is greater than X
30
Q

Why would you do an equivalence trial?

A
  • Existing effective treatment exists
  • Placebo-controlled trial unethical (ex: life-threatening illness)
  • New tx not substantially better than existing tx
31
Q

What are the types of trials that are classified based on how the participants are exposed to the intervention?

A
  • Parallel trials
  • Crossover (planned or unplanned)
  • Trials w/ factorial design
32
Q

What is a parallel RCT?

A

Px taking tx A and px taking tx B are taking them at the same time

33
Q

What is a planned crossover RCT?

A
  • Px are randomized to either tx A or tx B
  • After a period of time, all px stop tx and a washout period is conducted
  • Then those previously in tx A now take tx B and vice versa
34
Q

Example of unplanned crossover

A
  • Px are randomized to either surgical care or medical care groups
  • Those in surgical care group refuse surgery, so don’t get surgery (same as those in the medical care group)
  • Those in medical care group require surgery, so they get surgery (same as those in the surgical care group)
35
Q

Describe a factorial design trial

A
  • 1/4 of px get both tx A and B
  • 1/4 get A only
  • 1/4 get B only
  • 1/4 get neither A or B
36
Q

What are the types of trials that are classified based on the number of participants?

A
  • N-of-1 trials to mega-trials
  • Fixed size
  • Sequential trials
37
Q

Describe an N-of-1 trial

A
  • A form of crossover trial
  • Each participant receives the experimental arm for a period of time and then the control/ comparison arm during a different period of time
  • Participant doesn’t know which intervention is occurring during each period
  • *One of the best designs but one of the most expensive
38
Q

Describe mega-trials (“large simple trials”)

A
  • Meant to be huge but to collect only a limited amount of data (to make them affordable and practical)
  • Usually multi-center
  • Can pick up small effects
39
Q

Describe a sequential trial

A
  • Number of participants determined based on a priori sample size calculations; number not specified before trial begins
  • Has parallel design
  • Participants recruited until the question is answered (or it becomes clear that there is no possibility to detect a difference between the arms)
  • Usually principle outcome occurs (or not) shortly after the study begins
40
Q

What are the types of trials that are classified based on who knows what about the intervention that is being assessed?

A
  • Open trials
  • Single blind trials
  • Double blind trials
  • Triple and quadruple-blind trials
41
Q

Purpose of blinding

A

Used to increase the objectivity of the persons dealing w/ the randomized study (to prevent prejudice and bias)

42
Q

What is an open trial?

A

All participants and investigators know who is getting which intervention

43
Q

What is a single-blind trial?

A

Participants (usually) or investigators assessing outcome (alternately) don’t know the assignments

44
Q

What is a double-blind trial?

A

2 groups don’t know (usually participants and outcome assessors/ investigators)

45
Q

What is a triple or quadruple blind trial?

A

3 or 4 of the relevant groups aren’t aware of the tx assignment

46
Q

Which groups are considered relevant when blinding trials?

A
  • Participants
  • Investigators/ clinicians administering intervention
  • Investigators assessing outcomes
  • Data analysts
47
Q

What is a double-dummy trial? Is it beneficial?

A
  • When the placebo and active drugs look the same

- Gives more blinding to administration

48
Q

Potential benefits to blinding participants

A
  • Less likely to have biased psychological or physical responses to intervention
  • More likely to comply w/ trial regimens
  • Less likely to seek additional adjunct interventions
  • Less likely to leave trial w/o providing outcome data, leading to lost to follow-up
49
Q

Potential benefits to blinding trial investigators

A
  • Less likely to transfer their inclinations or attitudes to participants
  • Less likely to differentially administer co-intervention, adjust dose, withdraw participants, and/or encourage or discourage participants to continue trial
50
Q

Potential benefit to blinding assessors

A

Less likely to have biases affect their outcome assessments, especially w/ subjective outcomes of interest

51
Q

What is the difference between concealment of allocation and blinding?

A
  • Concealment of allocation = procedure to protect the randomization process before the subject enters the trial; always feasible; if not done, results in selection bias (randomization benefits are lost, and tx assignment is no longer truly random)
  • Blinding = masking of tx after randomization; not always feasible; if not done, can result in px biasing their responses or biased assessment

Year 3 - Sci Lit Final (10 decks)

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