RCT lecture Flashcards
What is the aim of an RCT?
To find out how effective a treatment is?
What is observational evidence?
Observing individuals being treated to see if the treatment works
What is pathophysiological theory?
Use a theory of the underlying physiology to determine which drugs should be used to treat them. However this can sometimes be wrong and must be tested by RCT
What is empirical evidence?
It is the actual results of the trial and can often prove theory wrong
What are the four main explainations of an observation?
Bias
Confounders
Chance
Hypothesis correct: effective
What is internal validity?
Looking at whether bias, confounders or chance have played a role in the observation
What is external validity?
This is also known as generalisability and is whether this is applicable to the population.
What are some of the factors that have to be considered in outside of external validity for should I treat?
Benefits worth harms
Resource costs
Patient preferences
Ethics
What is bias?
A difference in measurement before and after
What is confounding?
Some other factor has changed before and after e.g. the patient is taking some other medication
What is regression to the mean?
If we observe an extreme value then part of the reason for it being extreme is chance
Therefore the next value is more likely to be closer to the mean
This can give the impression of things getting better however this is mainly due to chance
This means that unusually high levels of something are more likely to be better next time you see them due to chance
What is the definition of an RCT
It is an intervention study where participants are randomised into two or more groups where the outcome is assessed.
What is the advantage of randomisation?
Means it reduces the effect of confounders as the confounders are allocated by chance
What are the main issues of RCTs?
Choice of outcome measure Ethics Choice of control Contamination (crossover) Bias in assessment of outcome Losses to follow up Sample size
What is the ideal outcome to measure?
measure the outcome that is relevant to the patient
What is equipoise?
The belief that one treatment is not better than the other that makes it ethical to randomise people into different groups
When choosing a control when would you use no treatment?
When there is no usual care and we don’t believe new treatment is effective. Cant disadvantage patients so must give next best usual treatment if there is one
What is contamination?
Participants randomised to the control group recieving the intervention
What is the advantage of intention to treat analyses?
Reduces risk of allocation bias
However it may underestimate the effect of the analysis
What is nominal data?
This is catagorical data e.g. you either die or you don’t, blood type, gender
What is ordinal data?
This is ordered catagorical data e.g. disease stage
What is discrete data?
This is quantitive data that are intergers e.g. progression- free and overall survival
What is continous data?
Quantitative data that can be any value e.g. height, mass
What type of intervention can contamination be a problem?
When education or information is an intervention as it can be easily shared with the placebo group.
