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MED 106- RESEARCH METHODS AND ESSENTIAL MEDICAL STATISTICS > 38. RANDOMISED CONTROL TRIALS > Flashcards

38. RANDOMISED CONTROL TRIALS Flashcards

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USMLE® Step 1 flashcards
1
Q
  1. What happens in a Randomised Control Trial?
A
  • participants are assigned to a study group

THE PROCEDURES ARE CONTROLLED:
- they make sure that all the participants in the study are
treated the same
- except for the intervention (independent variable)

THE PARTICIPANTS ARE ASSIGNED TO SPECIFIC TREATMENTS AT RANDOM:
- this means that they have an equal probability of being
assigned to any group

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2
Q
  1. What are the groups that are being studies in RCTs called?
A
  • they are called Study Arms
  • they can also be called Treatment Conditions
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3
Q
  1. Looking at this example, what can we say about the Crude Odds Ratio?
A
  • it is less than 1
  • this means that the exposure has a protective effect
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4
Q
  1. Looking at this example, what can we say about the Adjusted Odds Ratio?
A
  • it includes 1 in its value
  • this means that there is no association
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5
Q
  1. What is the effect of Randomisation?
A
  • it ensures that all the exposures in the sample as
    evenly distributed across the groups
  • there is a control group for the known and the
    unknown confounders
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6
Q
  1. What is the advantage of Randomisation?
A
  • it gives the researchers a sense of confidence
  • that the differences in outcome between the treatment
    and the control
  • are a result of the treatment alone
  • the test is fair

RANDOMISATION:
- will equalise the groups on all the other variables
- only the independent variable will have an effect

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7
Q
  1. Define: Allocation Concealment.
A
  • the researcher who has generates the Random
    assignment of exposures to participants
  • REMAINS BLIND
  • to what kind of condition the participants will enter
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8
Q
  1. What happens when the Allocation is not concealed?
A
  • the research staff are prone to assign patients who
    performed better to the intervention
  • rather than assigning the control

THIS CAN BIAS THE TREATMENT EFFECT:
- up to 20 to 30 %

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9
Q
  1. What are the two main aspects of Randomised Controlled Trials?
A
  1. RANDOMISATION
    - this reduces the risk of Confounding
  2. ALLOCATION CONCEALMENT
    - this has to do with Assigning
    - this reduces the risk of Selection Bias
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10
Q
  1. What is Blinding?
A
  • this prevents the Researchers from knowing certain
    information about a participant
  • this prevents the information from affecting how the
    researcher collects the data
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11
Q
  1. What is the best way to minimise Information Bias?
A
  • Double Blinding

BOTH THE PARTICIPANTS AND THE RESEARCHER:
- are kept blind to what exposure the patient has
randomly been assigned

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12
Q
  1. What is an example of a negative effect of lack of Blinding?
A
  1. A PARTICIPANT
    - may believe that a new drug is harmful
    - they will self-report in an exaggerated and biased way
  2. A RESEARCHER
    - may believe that a drug is extremely beneficial
    - they can over state the benefits of the drug

IN BOTH OF THESE CASES:
- the results differ from reality

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13
Q
  1. What is the set up of the simplest Randomised Controlled Trial?
A

IT HAS ONE INTERVENTION GROUP:
- this is the group receiving the treatment of interest

IT HAS ONE CONTROL GROUP:
- they are receiving the placebo
- or they are receiving another treatment

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14
Q
  1. Define: Placebo.
A
  • this is a substance
  • it is identical to the intervention substance
  • it lacks the active ingredient
  • this means it is chemically inert
  • it has no physical effect on the participant

NB:
- this is what leads to the Placebo Effect

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15
Q
  1. What is the Placebo effect?
A
  • it is a beneficial and psychological effect
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16
Q
  1. What causes the Placebo effect?
A
  1. THE PARTICIPANT’S BENEFICIAL RESPONSE TO THE
    INVESTIGATION
    - the patient’s response to a Therapeutic trial
  2. THE PATIENT’S BENEFICIAL RESPONSE TO
    OBSERVATION
    - and their response to assessment
  3. THE PATIENT’S BENEFICIAL RESPONSE TO THE
    DOCTOR-PATIENT INTERACTION
17
Q
  1. What do Placebo-Controlled Trials allow for?
A
  • they allow for us to study the effectiveness of the
    intervention treatment
  • it looks beyond all placebo effects
18
Q
  1. What is the advantage of Double-Blinding?
A
  • it reduces the influence of the expectations that the
    participants have
  • it reduces the influence of the expectations that the
    research staff have

THIS EXPECTATION IS ABOUT:
- which treatment will have a better effect on the
outcome

19
Q
  1. What is the most feasible kind of Blinding for Drug Trials?
A
  • Double-Blinding
  • the effect of the medication is being compared to a
    Placebo
20
Q
  1. How can we alter the Placebo to reduce Chance?
A
  • we can mask the Placebo
  • so that it looks identical to the drug being tested

EXAMPLE:
- make it look the same
- make it the same size
- make it the same colour
- make it taste the same
- make it have some similar side effects

21
Q
  1. In more complex RCTs, we can have several intervention groups and no placebo groups.
    What is always necessary in the Analysis Stage of a RCT?
A
  • one intervention group needs to act as the Control
    Group
22
Q
  1. What happens when we compare a new treatment to an old (conventional) treatment?
A
  • we use the old treatment as the Control group
23
Q
  1. What group is the Control when we are dealing with different dosages of a single treatment?
A
  • the control group is the one with the lowest dose
24
Q
  1. What is Partial Blinding ?
A
  • this is the type of blinding we use when Double
    Blinding is not possible

THE PARTICIPANT:
- is aware of what treatment they are receiving

THE RESEARCHER:
- is blind to the information about which treatment was
assigned to which participant

EVEN IF THE TREATMENT ASSIGNMENT IS KNOWN BY THE RESEARCHER THAT DELIVERS IT TO THE PARTICIPANT:
- the staff who assess the outcome should be kept blind
to this information

25
Q
  1. What are studies in which we cannot make use of Double Blinding?
A
  • studies that look at Behavioural Treatment
26
Q
  1. What are Unblinded Trials?
A
  • these are trials where neither the participant or the
    researcher are blinded

IN THIS CASE:
- the participants and the researchers have to have the
same expectations
- about the control condition and the treatment

27
Q
  1. Define: the State of Equipoise.
A
  • it is the ethical justification of conducting a trial
  • it is used when we do not know which intervention
    condition will work best
28
Q
  1. What does Randomisation prevent?
A
  • it prevents Biased Assessment of the outcomes after
    Randomisation
  • it prevents Measurement Bias
  • it prevents Ascertainment Bias
29
Q
  1. What does Blinding reduce?
A
  • it reduces non-compliance
  • it reduces contamination
  • it reduces self-report biases
  • it reduces investigator bias based on their opinions
30
Q
  1. In which situations is Blinding not possible?
A
  • in Open Trials

IN THIS CASE:
- a hard outcome must be chosen
- this is an exact numerical outcome
- the treatments must be standardised as much as
possible

31
Q
  1. When is Blinding hard to maintain?
A
  • when a drug shows specific side effects
32
Q
  1. What is the difference between Allocation Concealment and Blinding?
A

ALLOCATION CONCEALMENT:
- takes place before the participants are allocated their
exposure

BLINDING:
- takes place after the participants have been allocated a
specific exposure
- it can take place during the study
- it can take place when the outcome results are being
collected

MED 106- RESEARCH METHODS AND ESSENTIAL MEDICAL STATISTICS (43 decks)

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