RCT Flashcards
What is the difference between a controlled trial and an uncontrolled trial?
Uncontrolled trial: Everyone gets the treatment
Controlled trial:
* A treated group is compared with an untreated group (placebo)
* Or a treated group is compared with a control group having “usual treatment”
Name 3 benefits of randomised controls [3]
Proper randomisation helps ensure group receiving treatment A is similar to group receiving treatment B
Avoids selection/allocation bias
The only systematic difference between treatment and control groups is the treatment (hopefully)
What is the difference between single and double blinding of a clinical trial?
Single blind patients do not know what treatment they are on
Double blind: patients and the observers do not know what treatment the patients are on (not always possible)
What is the difference btween a parralel group and crossover trial?
When should you use each? [2]
Parallel group : when effect of treatment is not reversible
Cross-over: AB/BA study. Randomise patients to treatment sequence. Record outcomes for each and then swap over
when effect of treatment is reversible
Name three advantages and two disadvantages of cross over trials
Advantages:
* Each patient is their own control
* Smaller sample size to get same number of observations
* Better for subjective measurements
Disadvantages:
* More time consuming
* Carry-over effects – carry over effect of one treatment into other treatment period
Efficacy of chemotherapy to treat cancer
Parallel group
Cross-over
Efficacy of chemotherapy to treat cancer
Parallel group
Cross-over
What is a randomised cluster trial? [1]
Name two advantages [2]
Cluster Randomised Trials: Randomise pre-existing groups to one of two treatments.
- Avoids contamination.
- Enhances compliance.
Which should be designed as a cluster randomised trial?
Trial of aspirin versus placebo to prevent pre-eclampsia
Trial of addition of flocculant disinfectant to drinking water in the prevention of diarrhoea
Trial of text message reminders versus standard care to improve drug adherence
Which should be designed as a cluster randomised trial?
Trial of aspirin versus placebo to prevent pre-eclampsia
Trial of addition of flocculant disinfectant to drinking water in the prevention of diarrhoea
Trial of text message reminders versus standard care to improve drug adherence
Describe what a factorial trial is [2]
address two (or more) intervention comparisons carried out simultaneously, using four (or more) intervention groups.
Usually little or no interaction between the two interventions
Describe different phases of each clinical trial
Preclinical - Non-human study.
In vitro and in vivo animal experiments to obtain preliminary efficacy, toxicity and pharmacokinetic information
Phase 0 – First in-human trials.
Small number of subjects given sub therapeutic dose of drug to determine pharmacodynamics and pharmacokinetics
Phase 1 – Screening for safety
Testing of drug on (usually) healthy volunteers for dose ranging.
Determine whether the drug is safe to check for efficacy
Phase 2– Assess efficacy and safety
To determine whether drug can have a therapeutic effect
May be designed as case series or randomised controlled trial
Phase 3 – Assess efficacy and safety
Randomised controlled trial on large number of patients to determine therapeutic effect.
Phase 4 – Post-marketing surveillance
Safety surveillance (pharmacovigilance)
How do you calculate the relative risk of death in a treatment group? [1
How do you calculate the risk of death in control group? [1]
How do you calculate the relative risk of death in a treatment group compared to control group? [1]
If no effect of treatment, what does RR =? [1]
If no effect of treatment, RR = 1
COMPARE THE RESULT TO ONE
Which is the correct interpretation of a relative risk of 0.86?
Children of mothers in the treatment group were 14% less likely to have an IQ≤85 than children of mothers in the control group
The risk of a child having an IQ≤85 if the mother received treatment is 86%
Children of mothers in the control group were 14% less likely to have an IQ≤85 than children of mothers in the treatment group
Which is the correct interpretation of a relative risk of 0.86?
Children of mothers in the treatment group were 14% less likely to have an IQ≤85 than children of mothers in the control group - COMPARE THE RESULT TO ONE
The risk of a child having an IQ≤85 if the mother received treatment is 86%
Children of mothers in the control group were 14% less likely to have an IQ≤85 than children of mothers in the treatment group
Meta-analysis often used which type of plots? [1]
Forest plots
How can you tell if a meta-analysis has publication bias? [1]
Funnel plot: No publication bias the line would be symmetrical
