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Flashcards in Clinical Trials Deck (16):
1

Allocation concealment

Means that the person randomising the patient does not know what the next treatment allocation will be.

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Why is Allocation concealment Key to the success of randomisation

– Protects random sequence– Prevents selection bias (also called allocation bias)

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Allocation concealment types

• Assignment by centralised 24 hour hotline (remote telephone )
• Pre-numbered or coded containers administered as per allocation
• Computer allocation • Sequentially numbered, sealed, opaque envelopes

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Blinding

Masks the assigned intervention during the whole trial•Why?–Reduces influence of subjectivity–Minimise observer bias

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Intention to treat

ALL participants analysed in the group assigned (irrespective of whether or not they completed, or received the treatment)
Why?•Preserves randomisation•Models real world

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Per protocol analysis

Only analyse participants who were compliant with thestudy protocol

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Complete case analysis

Only analyse participants with available outcome data.

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Differences only explained by ...

1.Random error2.Treatment effect3.Systematic error

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Elements of a research question

PICOT:
Participants- Who
Intervention What
Comparison What
Outcomes What
Time when

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Types of trials

Parallel group trial
Factorial trial
Cross-over trial

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Trial phases
Phase 1•

First in humans: Evaluates safety, dose & PK/PD. Not randomised. In healthy volunteers or people with advanced disease (e.g. cancer). N=20-60. Extensive monitoring, clinic or hospital-based

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Trial phases
Phase 2a•

In target population: Small (<100 people), short-term studies of safety, dose ranging & “surrogate”efficacy, sometimes randomised.

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Trial phases
Phase 2b•

In target population: Larger (100s) short-term studies of surrogate & target outcome, Randomised.

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Trial phases
Phase 3•

In target population: Large (100-1000s), looks at long-term efficacy or effectiveness, and safety. Randomised. Looks at acceptability. Compares to usual care or as an adjunct.

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Trial phases
Phase 4•

In target population or general popn: Post-marketing surveillance, often pragmatic, and head-to-head comparison. Looks at acceptability, picks up rarer adverse events

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Good Design Elements:

® Randomisation
o Reduces confounding and produces equal groups
® Allocation Concealment
o Reduces selection bias
Blinding
o Reduces observer bias
® Complete Follow Up
o Reduces attrition bias
® Right Analysis
o Reduces Attrition bias