Block 3 Week 3 - RCT Flashcards
What are the lessons we have learnt from history about how we should conduct trials?
1) Collect data- don’t rely on anecdotal
2) The need for Controls
3) Avoid bias
What may the differences in outcomes in Tx groups be due to?
How must the controled and the trial group differ?
Why must the sample be sufficiently large
Treatment effect, Bias or Chance
2) Must be alike in every possible way except the Tx
3) To avoid chance imbalance
What is a controlled clinical trial?
Prospective study comparing the effects & value of an intervention against a control in human subjects
What is an uncontrolled trial?
Trial involving no control group
What is an Randomised Clinical Trial?
What are the advantages
Contolled clinical trial where the therapies are allocated by a chance mechanism- neither patient or physician know which therapy they will revieve in advance
Advanatage:
a) Limit selection bias
b) Balance prognostic factors
c) Validity of satistical tests
How are clinical trials classified by design in order of weakest strenght - most strength
a) Uncontrolled trials
b) Historical controls (the comparison group is running concurrently to the treatment group- comparison between two different times)
c) Current non-randomised controlled
d) Randomised controlled
Overall- Improved design reduced bias
What is the concept of statistical inference?
What are its aims
Analysed data results in a selected sample are used to infer how all the population would behave
Population- people going into the study → Protocol Treatment Patients- are people fit to go through the process → Observed Result → Extrapolate
Estimate treatment effect (bias beware)
Aware of: Variabilty of estimate due to samplaing from population (How may population variabilty affect the study)
Goal: Control bias & reduced variability
Randomised allocation means……
a) Gives an equal chance of receiving each Tx
b) In long run leads to groups that are likely to be similar in characteristics by chance
c) Reduced selection bias if patients enter trial before randomisation
d) is used in other expirimental settings
What is the placebo effect?
Even if the therapy is irrelavent to the patient’s condition, the patient’s atttidue, to their illness & the illness may be improved by a feeling that something is being done about it
If you are comparing a group with Tx and a group without Tx what could the results be down to?
True tx effect
OR
Placebo effect
What are the two types of blind trial?
What is the aim of this?
Single Blind Trial: Either the patient, clinician or assessor does not the Tx allocation
Double Blind Trial: Two or more of the patient, clinician or assessor do not know the Tx allocation
Aim: Reduce placebo effect that could bias comparisons between Tx
What is the Outcome evaluation?
a) If there is a difference between groups
b) Could the difference have arisen by chance- is it statistically significant
c) How big is the difference- is it clinicall relavent
d) If the difference is attributable to the Tx
Non-compliance:
Why may participants not complete the trials
Why doesn’t everyone comply with their allocated Tx?
A) Due to clinical condition necessitating their removal
OR
Want to withdraw
B) Misunderstood the instructions
Don’t like taking the Tx
Don’t feel the Tx is working
Draw a diagram showing from randomisation how a clinical trial is conducted
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What are the 2 different interpretiations of the new treatment?
1) Is the Physiological Action better (drug effects)
OR
2) Is the new tx better than the standard tx in Clinical Practice (tx package)