Interpreting Results Flashcards
What is mean or mean change with respect to results?
Generally describes a continuous outcome such as blood pressure
What is a propotion?
The fraction of the total that possesses the outcome
What is the Absolute risk reduction or absolute risk difference?
This is the difference between the probability of the event in the control group and probability of the event in the intervention group
What does the ARD tell us?
The proportion of an event utilizing a specific treatment compared to the proportion of and event occurring in the placebo group
What os the relative risk?
It shows what the risk of the outcome in the intervention group is compared to the risk in the control group
Probability of event (Intervention group)/probability of event (Control group)
Take some time to look at how they calculated the relative risk example
What circumstance can we not calculate the relative risk?
Cannot calculate for mean change such as BP, BMI, waist circumference
What does a Relative risk of 1 mean?
No difference in risk group
What does a relative risk of <1 mean?
Less risk of outcome in the intervention group
What does a relative risk of >1 mean?
Higher risk of outcome in intervention group.
What is the relative risk reduction?
The degree to which the baseline risk is reduced or increased by the intervention
Take some time to review how to do these calculations
What is an Odds ratio
Shows the odds of the outcome occurring in the intervention group compared to the control group (Double calculation required)
Take some time to review how we calculate an odds ratio
Take some time to review how we calculate an odds ratio
What does an odds ratio of 1 mean?
No difference in odds between gorupsWa
What does an odds ratio of less then 1 mena?
Less odds of outcome in intervention group
What does an odds ratio of greater then 1 mean?
Higher odds of outcome in intervention group
What is the number needed to treat?
THis is a vlaue where we take 100 and divide it by the number needed to treat.
What does the NNT tell us?
Tells us the number of people that are needed to treat in order to prevent a stroke in one additional person compared to the control
What does a hazard ratio tell us 1, <1, >1?
No difference, less hazard of outcome in intervention group, Higher hazard of outcome in intervention group
What is the confidence interval?
Range where the true effect of the intervention/treatment lies
What does a narrower CI indicate?
More precises results
For means or proportions what is the no difference threshold?
0
For relative risk or odds ratio waht is the no difference threshold for CI?
1
Mean and ARD associate to what threshold in CI?
0
RR and OR assocaite to waht threshold in CI?
1
What is a main difference between confidence interval and p value?>
Direction of the effect and if a difference exists
What is somehting that CI can help distinguish between?
Clinical and statistical significance
What is a superiority based study?
Where we want to show an intervention is better than control. attempting to establish a
What is a non-inferiority based study?
We are trying to determine whether the new intervention is not substantially worse than an establised intervention
What is the non-inferiority margin determined by?
This is a value that is decided based on a combination of stats reasoning and clinical judgement
What is the propensity scores?
Probability that a subject would be in a particular treatment group based on their observed baseline chracterisitcs
Why is ITT preferred?
It takes into consideration all people who even dropped out of the study
What is per protocol?
Where it is done by the study and analyzed as designed Confounding may be an issue
With a non inferiority trial what do we want to see?
Both and ITT and per-protocol and comparing them at the end
What is key in a non inferiority trial?
Confidence intervals
what do Non inferiority tests need to be compered to?
Need to be compared to our best possible treatment
What is a propensity scores?
probability that a subject would be in a particular treatment group based on their observed baseline characteristics
Assigns a score that helps to organize each subject in the cohort for study design and analyses (Mac and PC, Propensity scores both of 0.6, and we would match them together)
It takes in alot of variables
What is the goal of propensity scores?
mimic RCTs by balancing observed characteristics between study groups
What is a adaptive clinical trial design?
Where a clinical trial designs allows for prospectively modifications to one or more aspects of the design based
Review adaptive clinical trial design
What should an adaptive clinical trial design include?
Preplanned all the interim analysis and potential modifications
Interim data analyses which can lead to operational bias
