Topic 2: Controls Flashcards
5 types of control group
Placebo, no treatment, different active treatment, different dose or regimen of the trial treatment, multiple control groups.
What are disadvantages of using a placebo control
Ethical concerns about giving someone a placebo especially when there is a standard treatment a patient could receive outside of the trial. Not a pragmatic control group, so may be issues with generalisability, and cannot demonstrate effectiveness.
Advantages of placebo control
Demonstrates efficacy and safety, since you can attribute adverse effects to the drug. Treatment effect is likely to be higher, and so a smaller sample size required - more efficient.
What is a placebo
A treatment that contains no active ingredient
What is the placebo effect
When a patient exhibits a response to the treatment, even though the treatment cannot give a direct effect
When is there less justification for the use of a placebo
When the outcomes are objectively defined
When is using no treatment as a control appropriate
When a placebo controlled cannot be performed, in surgery for example.
What are the advantages and disadvantages of using no treatment control
Similar to using a placebo
What are the advantages of using a different active treatment
Ethical and practical, giving interpretable evidence of efficacy and relative efficacy
Disadvantages of using a different active treatment
Greater difficulty in quantifying safety outcomes since there is no comparison to no treatment. Treatment effect is likely to be smaller, so a larger sample size needed - less efficient.
Advantages of using a different dose control
It is possible to fit a trend across several treatment groups, reducing the necessary sample size and showing efficiency
Disadvantages of different dose control
A positive dose response trend without significant pair wise differences mat leave uncertainty as to which doses other than the highest were effective. Without comparing to no treatment, no differences between doses is an uninformative outcome.
