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Clinical Trial Design > Week 1 > Flashcards

Week 1 Flashcards

1
Q

Phase I:

A
  • First stage in testing a new intervention in humans
  • Usually 10-30 people
  • Identify tolerable dose, provide information on drug metabolism, excretion, and toxicity
  • Often not controlled
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2
Q

Phase II:

A
  • Usually 30-100 people

- Preliminary information on efficacy, additional information on safety and side effects

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3
Q

Phase III:

A
  • Usually 100+ people
  • Assess efficacy and safety
  • Controlled, usually randomized
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4
Q

Parallel Design

A
  • Simultaneous treatment and control groups
  • Each person is randomly assigned to one treatment group
  • Randomization removes treatment selection bias and promotes comparability of treatment groups
  • Statistical comparisons made between treatment groups
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5
Q

Crossover Design

A
  • Randomization of order in which treatments are received
  • Testing of both treatments in each patient
  • Fewer patients needed
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6
Q

Randomization of order in which treatments are received

A
  • AB or BA

* Randomization promotes balance between treatment groups in the timing of exposure

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7
Q

Testing of both treatments in each patient

A
  • Each patient serves as his/her own control

* Variability reduced because less variability within patient than between patients

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8
Q

Crossover Design: Disadvantages

A
  • Treatment can’t have permanent effects or cures
  • Potential carry-over effects of first-period treatment to the second period
  • Test for a period by treatment interactions not powerful
  • Dropouts more significant
  • Analysis may be more difficult
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9
Q

Potential carry-over effects of first-period treatment to the second period

A
  • Washout needs to be long enough
  • Unequal carry-over effects
  • Treatment during washout
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10
Q

Crossover Design: Uses

A

Constant intensity of underlying disease
Short-term treatment effects
Metabolic, bioavailability, or tolerability studies

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11
Q

Constant intensity of underlying disease

A

Chronic diseases—asthma, hypertension, arthritis

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12
Q

Group Allocation Design

A
  • Also known as “cluster randomization”
  • Randomization unit is a group of individuals (community, school, clinic)
  • Individual randomization and intervention is not feasible or is unacceptable
  • If there is a correlation in the responses within a group, design loses some efficiency (more individuals required)
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13
Q

Individual randomization and intervention is not feasible or is unacceptable

A
  • Tracking

- Contamination

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14
Q

Individual randomization and intervention is not feasible or is unacceptable

A
  • Tracking

- Contamination

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15
Q

Factorial Design

A
  • Two interventions tested simultaneously, either as . . .
    1. Economical way to test two treatments simultaneously, or
    2. Method to test for treatment interaction
  • For testing two treatments simultaneously, assumption is of no interaction
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16
Q

For testing two treatments simultaneously, assumption is of no interaction

A
  • Treatments have independent mode of action

- More plausible if different outcome

17
Q

Large, Simple Design (Features)

A

Features

  • Very large number of patients (many study sites)
  • Broad eligibility criteria
  • Minimal data collection requirements
18
Q

Large, Simple Design (Rational)

A
  • Modest benefits require large sample sizes
  • Treatment interactions unlikely, so baseline characteristics and interim response variables are not needed
  • Less precision (more error, increased variance) is tolerated; countered with large numbers
19
Q

Large, Simple Design: Requirements

A
  • Easily administered intervention
  • Easily ascertained outcome
  • Short-term follow-up
  • No complex baseline measurements
  • Simple data are persuasive enough
20
Q

Easily administered intervention

A
  • Short-term adherence
  • No treatment adjustment
  • No ongoing monitoring for adverse events
21
Q

Equivalence Design

A

Objective—show that intervention response falls sufficiently close to control group response

22
Q

Non-Inferiority Design (Objectives)

A
  • Determine whether treatment A (frequently a new treatment) is at least as good as treatment B (frequently an established treatment)
  • Test, if hypothesis A is worse than B, than one can be rejected (one-sided)
23
Q

Adaptive Design: Definition

A
  • an adaptive design clinical study is defined as a study that
  • includes a prospectively planned opportunity for modification of one or more specified aspects of the study design
    *and hypotheses based on analysis of data (usually interim data) from subjects in the study.
    *Analyses of the accumulating study data are performed at prospectively planned timepoints within the study,
  • can be performed in a fully blinded manner or in an
    unblinded manner,
  • and can occur with or without formal statistical hypothesis testing.
24
Q

Possible Adaptations in Adaptive Designs

A
  • Randomization probabilities
  • Sample size
  • Visit schedule
  • Hypotheses tested
25
Q

Principles of Adaption

A
  • Adaptation must be pre-specified

* IRB approval includes adaptation plan

26
Q

Adaptation must be pre-specified

A
  • Define adaptation triggers in protocol

- Define adaption

27
Q

adaptation triggers in protocol

A
  1. After n-enrolled, re-evaluate sample size/power
    calculations based on interim results
  2. Enroll from two subpopulations until time t and then look at response rate in both populations
28
Q

Define adaption

A
  1. Increase or decrease sample size to maintain power
  2. If response is p% larger in one population, continue
    recruitment only in that population
29
Q

adaptation plan

A
  • Amendments not needed to change according to plan

- Amendment may be needed for other changes

30
Q

Advantages of Adaptive plan

A
  • Flexibility
  • May be more efficient (shorter duration, fewer people)
  • May be more likely to show effect if one exists
31
Q

Limitations of Adaptive Plan

A
  • Can be difficult to explain design and interpret results
  • Rely on interim results to change trials
  • May provide interim information on efficacy and safety to investigators and sponsor
  • May be hard to implement
32
Q

Why the Adaptive plan can be hard to implement

A

 Need quick access to data

 Extensive documentation

Clinical Trial Design (1 decks)

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