Understanding clinical trial designs Flashcards
1
Q
What is a clinical trial?
A
- a type of clinical research that compares one treatment or intervention with another
- May involve patients or healthy people or both
- any research that prospectively assigns human participants or groups of humans to one or more health-related interventions to evaluate the effects on health outcones
2
Q
What is bias?
A
- aims to obtain groups where the only systematic difference are the interventions under investigation
- Flaws in the design and conduct of a trial can introduce bias - i.e. Other systematic differences between the treatment groups
- can severly hamper the interpretation of the results of the trial
3
Q
What are the different types of bias?
A
- Selection
- Performance
- Attrition
- Detection
- Reporting
4
Q
What is selection bias?
A
- systematic difference between groups in how participants receibe intervention/control
Methods of minimising bias:
- Randomisation allocation concealment
5
Q
What is performance bias?
A
- sys difference between groups in how particpants are cared for, co-interventions
- Methods of minimising bias:
- Blinding of participants, team and assessors
to minimise bias
6
Q
What is attrition bias?
A
- Numbers of participants dropping out , non-random withdrawl
- minimise bias: intention to treat analysis
7
Q
What is detection bias?
A
- How outcomes assessed
- Objective outcome measures
- Blinded outcome assessors
8
Q
What is reporting bias?
A
- Which outcomes are reported
- minimise bias: registration of trials
9
Q
Why should we randomise?
A
- problems with:
- historical controls
- non-randomised concurrent controls
- Factors (known and unknown) that might affect outcome similar in each arm of the trial
- Basis of statisrical inference
10
Q
How do we avoid performance and detection bias?
A
- Blinding : witholding knowledge of treatment AFTER assignment
- Trial participants
- Healthcare providers
- Data collectors
- Outcome adjudicators
- Data analysts
11
Q
What is ITT analysis?
A
- Exclusion of participants from the analysis can undermine randomisation
- Any exclusion should be carefully justified
- Where possible include all participants and “analyse as randomised - the intention to trear principle
- This provides an unbiased estimate of the effect of being assigned to an intervention
12
Q
What is the registration of trials?
A
- Registration = the first step towards research transparency and future dissemination of outcomes
- Ensures all healthcare decisions are informed by all available evidence
- Provides opportunity for collaboration and reduces duplication of research efforts
- Improves awareness of trials for clinicians , researchers, patients and public
- TRIALS MUST BE REGISTERED
13
Q
What are different trial designs?
A
- parallel group
- crossover
- factorial
- cluster
- platform trials
14
Q
What are parallel groups ?
A
- groups receive different interventions in the same time period
- all participants have the same outcome assessments
- the groups are compared
15
Q
What are pros and cons of parallel group trials?
A
Pros:
- simple
- robust
- both groups treated in the same time period
Cons:
- only provides differences between groups
- large studies required to study rare events