Clinical Trials Chapter 1 Flashcards
What are clinical trials?
Research studies involving patients which compare a new or different type of treatment or preventative measure with the standard practice.
Look for the best way to prevent, diagnose or treat illnesses
Why do we need clinical trials?
They are the most reliable way of testing
Test if they are safer and more effective than the current best treatment
Have to go through a number of different phases to be licensed through relevant medical agencies
Why is randomisation needed?
- So that strong conclusions may be drawn regarding the effectiveness and safety of a new treatment compared to a current standard treatment
- Such conclusions are only valid if the trail is sufficiently powered and there are no threats to the validity of conclusions
- Use of randomisation in clinical trials contributes to establishing validity of the inferences
Methods of randomisation: Simple randomisation
Procedure in which patients are randomly assigned to a treatment group and each participant has the same probability of being assigned to any particular treatment group.
- flip a coin
- use an envelope
- generate random number using a computer, each person allocated a number randomly e.g 1-50 goes in group A and 51-100 in group B
Methods of randomisation: Simple randomisation
Possible problems
Reduces bias by equalising some factors that have not been accounted for in the trial (age, sex, disease severity)
But there is a chance for imbalance, e.g imbalanced distribution of sex between the treatment and control groups
Methods of randomisation: Stratification
A stratification factor is a categorical (or discretised continuous) covariate which divides the patient population according to its levels
- sex 2 levels: male and female
- age can have multiple levels
- disease status
Randomisation is then conducted within each stratum.
Very easy to implement
