Interventional Study Designs Flashcards

1
Q

What study designs are thought to be the only ones that can prove causation?

A

interventional studies

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2
Q

What are some other terms for interventional studies?

A

clinical trial, clinical study, experimental study, human study, investigational study

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3
Q

What is the key difference between interventional and observational studies?

A

In interventional, investigator selects interventions and allocates study subjects to forced-intervention groups. They are more “rigorous” in ability to demonstrate causation.

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4
Q

What is the pre-clinical phase of an interventional study?

A

study phase that does NOT involve humans; it may involve animals.

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5
Q

In general, the higher the phase, the higher the _____

A

population.

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6
Q

What is phase 1 of an interventional study?

A

phase in which healthy volunteers (20 - 80) are used to asses safety, dose, toxicity of a drug. It is a short duration.

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7
Q

What is phase 2 of an interventional study?

A

phase in which 100 - 300 patients with condition of interest are used to determine efficacy; safety is still important. It is short to medium in duration.

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8
Q

What is phase 3 of an interventional study?

A

Phase in which 1000 - 3000 patients with condition of interest are tested, with a PRIMARY purpose of efficacy. It also uses superiority, non-inferiority and equivalency formats.

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9
Q

What is another word for placebo?

A

Dummy

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10
Q

What is phase 4 of an interventional study?

A

Long term effects of a drug in a large population are assessed. The goal is maintain long-term safety. It may rely on registries and surveys and can also be considered an observational study.

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11
Q

What kind of study is phase 4 sometimes considered to be?

A

observational

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12
Q

What are the advantages of interventional trials?

A

they can show causation and they are the only studies used by the FDA.

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13
Q

What are the disadvantages of interventional trials?

A

cost, time, ethics, and most importantly external validity - are the conditions of the study applicable to the general population?

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14
Q

What is a feature of explanatory studies?

A

they are generally restrictive in the amount of dosages, etc. given to each patient. They do not have much flexibility.

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15
Q

What is a feature of pragmatic studies?

A

they are more flexible - drug combinations may be compared, placebos may not be used, and regulat people with multiple comorbidities are studied.

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16
Q

What is a simple interventional study?

A

A study in whcih patients are randomized only once. Patients are divided into two groups, and a single hypothesis is tested.

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17
Q

What is a factoral interventional study?

A

A study in which subjects are randomized at least twice; groups are divided into sub-groups. It is used to test multiple hypotheses at the same time.

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18
Q

What is a negative of a factorial study?

A

More participants are needed in order to answer more questions.

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19
Q

What are benefits of a factorial study?

A

Efficiency, sample size, complexity are improved, and the study is not as generizable.

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20
Q

What are parallel interventional studies?

A

Studies in which groups are randomized, and no switching of intervention groups occurs after that.

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21
Q

What are two types of parallel studies?

A

simple and factorial

22
Q

What are cross-over studies?

A

Studies in which groups serve as their own control by crossing over from one intervention to another during a study. IT allows for a smaller sample size.

23
Q

What is the washout period?

A

The period in which subjects return to their baseline health (e.g. the drugs are out of their system).

24
Q

What is the run in/lead in phase of an interventional study?

A

Phase in which all study subjects are given one or more placebos for initial therapy (defined time-period) to determine an new baseline of disease.

25
Q

What are disadvantages of cross over designs?

A

they are only suitable for long-term conditions, effects may carry over into other groups, complexity in data analysis,

26
Q

What is the most important endpoint of a study?

A

the primary outcome. It is the main research question used for developing/conducting a study

27
Q

What is a composite outcome?

A

An outcome that combines multiple endpoints into a single outcome. It could be considered a primary outcome.

28
Q

What are patient-oriented outcomes?

A

Outcomes that are very significant; they can include death, stroke, hospitalization, etc.

29
Q

What are surrogate markers?

A

elements used in place of evaluating patient-oriented endpoints, such as blood pressure for risk of stroke.

30
Q

What are non-random sample selections/allocations?

A

Allocation in which subjects do not have an equal probability of being selected or assigned to each intervention group.

31
Q

What are random sample selections/allocations?

A

Allocation in which subjects have an equal probability of being assigned to each intervention group.

32
Q

What is the purpose of randomization?

A

To make the groups as equal as possible, based on known and unknown important factors (confounders).

33
Q

What does randomization not guarantee?

A

equality of groups.

34
Q

What is is simple randomization?

A

Randomization in which there is an equal probability for allocation within one of the study grups.

35
Q

What is blocked randomization?

A

ensures balance WITHIN each intervention groups (e.g. that they are equal in size).

36
Q

What is stratified randomization?

A

ensures balance with known confounding variables (e.g. there is an equal distribution of healthy and sick patients in each group).

37
Q

What is a single blind masking study?

A

Study subjects are not informed of the intervention they are receiving, but the clinicians are!

38
Q

What is a double blind masking study?

A

Neither clinicians nor patients are informred of the intervention one is receiving.

39
Q

What is a open-label study design?

A

everyone knowns which intervention each subject is receiving.

40
Q

What can post-hoc surveys be used for?

A

ensuring adequacy of blinding; if the subjects can easily guess which group they are in, the blinding was not successful.

41
Q

What is a placebo therapy?

A

a form of blinding in which the placebo treatments are identical to the active treatments. Double dummy is when more than 1 placebo is used.

42
Q

What is the placebo-effect?

A

Patients may think they are better due to the type of care they are receiving or the way they are asked questions.

43
Q

What is the hawthorne effect?

A

Patients report positive results in placebo because they desire the study to have successful results.

44
Q

What is post-hoc sub-group analysis?

A

When researchers compare groups in multiple ways in order to find some sort of correlation; it can be misleading and increases risk of type II errors.

45
Q

How are drop-outs or lost to follow-ups managed?

A

they are either included or not included in the study.

46
Q

What is intent-to-treat?

A

A researcher uses the information from a drop-out in the study, and converts all missed assessments to a null effect.

47
Q

What are the benefits of intent-to-treat?

A

it preserves the randomization process, baseline characteristics, group balance, and maintains statistical power.

48
Q

What is “as treated” management?

A

group assigments are ignored, and subjects are allowed to switch groups and be in groups they moved to, ended in, or stayed in the most.

49
Q

What is a disadvantage of per-protocol analysis?

A

it biases the estiamtes of effect (commonly over-estimates effect).

50
Q

How do researchers assess adherence (compliance)?

A

pill counts, bottle counter-tops and drug levels.

51
Q

How to researchers improve adherence (compliance)?

A

frequent follow-ups, treatment alarms/notifications, medication facts/dosage containers.