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Epidemiology > Interventional Studies > Flashcards

Interventional Studies Flashcards

1
Q

What are some other terms that can be used for interventional studies?

A
  • Clinical trial
  • Clinical study
  • Experimental study
  • Human study
  • Investigational study
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2
Q

Key difference between interventional and observational studies

A
  • Can show causation

- investigator selects interventions and allocates study subjects to forced intervention groups

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3
Q

What are the different aspects that determine the different phases of interventional studies?

A
  • Purpose/Focus
  • Population studied (healthy/diseased)
  • Sample size
  • Duration
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4
Q

What does the duration of the study depend on?

A
  • the disease or the research question being asked
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5
Q

What is the purpose of the pre-clinical stage?

A
  • helps drive the hypothesis
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6
Q

Phase 0

A
  • Asses drug-target actions and pharmacokinetics in non-therapeutic/non-diagnostic doses
  • Healthy volunteers (or cancer patients)
  • Very small (<20)
  • Very short duration (single dose to a few days)
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7
Q

Phase 1

A
  • Asses safety/tolerance and pharmacokinetics of one or more dosages
  • Healthy or disease volunteers (depending on disease)
  • Small (20-80)
  • Short duration (a few weeks)
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8
Q

What are some aspects of pharmacokinetics?

A
  • Absorption
  • Distribution
  • Metabolism
  • Excretion
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9
Q

Phase 2

A
  • Asses effectiveness (while still looking at safety and tolerability)
  • Diseased volunteers
  • Larger N (100-300)
  • Short to medium duration (few weeks to a few months)
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10
Q

Phase 3

A
  • asses effectiveness (safety and tolerability as well)
  • diseased volunteers
    Uses the different perspectives
  • Larger N (300-500)
  • Longer duration (few months to a year)
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11
Q

Phase 4

A
  • post FDA approval
  • Assess long term safety, effectiveness and optimal use (risks/benefits)
  • Diseased volunteers (comorbidities)
  • population N (100,000 - millions)
  • Longer duration (many years to decades)
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12
Q

Advantages of Interventional Trials

A
  • Cause precedes effect (can demonstrate causation)

- Only design-family used for FDA approval process

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13
Q

Disadvantages of Interventional Trials

A
  • Cost
  • Complexity/Time
  • Ethical considerations
  • Generalizability
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14
Q

Simple Interventional studies

A
  • Divides (randomizes) subjects once

- Tests a single hypothesis at a time

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15
Q

Factorial Interventional Studies

A
  • Divides (randomized) into groups and then further sub-divides each of the groups into additional sub-groups
  • Used to test multiple hypotheses at the same time
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16
Q

What are some characteristics of factorial interventional studies?

A
  • Improves efficiency for answering clinical questions
  • Increases study population sample size
  • Increases complexity (which may be a recruitment barrier)
  • Increases risk of drop outs
  • May restrict generalizability results
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17
Q

Parallel Interventional Studies

A
  • groups simultaneously and exclusively manages
  • no switching of intervention groups after initial randomization
  • All simple and factorial study designs are also parallel
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18
Q

Cross-Over (Self-Control) Interventional Studies

A
  • Groups serve as their own control by crossing over from one intervention to another during the study
  • Allows for smaller sample size
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19
Q

What is a washout period?

A

Refers to the break that happens after a certain time frame in a crossover study. Before the groups are switched.

20
Q

Run-In/ Lead-in Phase

A
  • determining a new baseline
  • cleaning out and baseline establishment before a study starts

Can also be a practice and dry run before the actual study

21
Q

Disadvantages of Cross-Over Design

A
  • only suitable for long term conditions that are not curable or which treatment provides short term relief
  • Duration of study for each subject is longer
  • Carry-over effects during crossover
  • Treatment-by-period interaction
  • Smaller N requirement only applicable if within-subjects variation less than between-subjects variation
  • Complexity in data analysis
22
Q

Primary Outcome

A
  • Most important, key outcome

- Main research question for developing/conducting study

23
Q

Secondary/Tertiary etc. Endpoints

A
  • Lesser importance but still valuable
  • Possible for future hypothesis generation

E.g. Side Effects

24
Q

Composite Endpoints

A
  • Combines multiple endpoint into a single outcome

Can also be called group outcome

25
Q

Examples of Patient oriented Endpoints

A
  • Death
  • Stroke or MI
  • Hospitalization
  • Preventing need for dialysis
26
Q

Examples of disease-oriented endpoints

A
  • Blood pressure (for risk of stroke)
  • Cholesterol (for risk of heart attack)
  • Change in SCr (for worsening renal function)
27
Q

Non-Random Sample Selection & Group Allocation

A

Subjects don’t have an equal probability of being selected or assigned to each intervention group

28
Q

Random Sample Selection and Group Allocation

A

Subject do have an equal probability of being assigned to each intervention group

29
Q

What is the purpose of randomization?

A
  • to make groups as equal as possible; based on known and unknown important factors.
  • Equality of groups in not guaranteed
30
Q

Forms of Randomization

A
  • Simple
  • Blocked
  • Stratified
31
Q

Simple Randomization

A
  • Equal probability for allocation within one of the study groups
32
Q

Blocked Randomization

A

Ensures balance within each intervention group.

33
Q

Stratified Randomization

A

Ensure balance with known confounding variables

  • gender, age, disease etc
  • can preselect levels to be balance within each interfering factor
34
Q

Types of Masking

A
  • Single-blind
  • Double-blind
  • Open-Label (unmasked/unblinded)
35
Q

Single-blind

A

Subjects not informed but researchers are

36
Q

Double blind

A

Neither the subject nor the researcher knows which groups the subjects are in

37
Q

Open-Label

A

Study subjects and researcher both know which intervention is being received

38
Q

Forms of Blinding (Masking)

A
  • Placebo (dummy therapy)
  • Placebo-effect
  • Hawthorne effect
39
Q

Placebo

A
  • Inert treatments made to look identical to active treatments
40
Q

Placebo Effect

A

Improvement in condition by power of suggestion of being treated

41
Q

Hawthorne Effect

A

Study subjects change their behavior solely due to awareness of being studied/observed

42
Q

Post-hoc sub-group analysis

A
  • Not accepted as appropriate, by most, when not planned before
43
Q

Intention to Treat

A

Uses the last know assessment carried forward when a patient is lost to follow-up

Also can use the baseline moving forward

44
Q

What does intention-to-treat result in?

A
  • preserves randomization process
  • preserves baseline characteristics and group balance at baseline which controls for known and unknown confounders
  • maintains. Statistical power
45
Q

How can you manage drop-outs and lost-to-follow-ups?

A
  • Ignore them - include only those that complied

- Treating them as treated - if they happen to be on the drug that you are looking at you use those results

46
Q

Assessing Adherence (compliance)

A
  • Drug levels (multiple useful sites)
  • Pill counts at each visit
  • Bottle counter-tops
47
Q

Methods of Improving Adherence (Compliance)

A
  • Frequent follow-up visits/Communications
  • Treatment alarms/notifications
  • Medication blister packs or dosage containers

Epidemiology (12 decks)

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