1 - Clinical Trials Flashcards
What is the gold standard for clinical trials?
Blind randomised controlled trial as blinding reduces bias, random minimises confoundiing and comparison with a control enables additional therapeutic benefit
What is the definition and purpose of a clinical trial?
- Form of planned experiment which involves patients and is used to decide the most appropriate method of treatment for future patients
- Used to collect evidence of the efficacy and safety of the treatment in testing
- After results you then look at 95% CI to see if statistically significant and if p>0.05 due to 1 in CI then can reject null
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What does efficacy and safety mean when testing a treatment in a clinical trial?
Efficacy: ability of the intervention to improve health
Safety: ability of the intervention to do no harm
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In order to be a fair comparison of efficacy and safety what three conditions must a clinical trial satisfy?
RANDOMISED CONTROL TRIAL
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What are the different phases of drug development?
- Research: look at lots of compounds and animal testing may be implemented. Screening of different compounds through HTS
- I: small no of healthy volunteers
- II: small no of patients with disease
- III: large no of patients with disease and first control
- IV: long term safety after approval
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What are the disadvantages of non-randomised clinical trials and the use of historical controls in a clinical trial?
- Non-random: allocation bias and confounding
- Historical controls: selection less defined, old group may be treated differently (e.g different hospital protocols decades ago), less information about confounders, unable to control confounders
What are the steps involved in a RCT?
1. Define the factors: disese of interest, treatments being compared, outcomes being measured, possible confounders, eligible patients
2. Conduct the trial: identify a source of patients and invite/consent eligible patients to the trial. Allocate the patients in a random way to stop allocation bias and confounding, e.g random number generator. Follow up patients and minimise loss
3. Comparison of Outcomes: is there an observed difference, is it statistically significant, is it clinicall important or a big enough difference, was the study design good
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What is the p value?
p<0.05 as the null hypothesis is out of the CI so cannot reject the null
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Why must outcomes be defined before a clinical trial?
- Prevent data dredging and repeated analysis
- Created a protocol for data collection and agreed criteria for measurement of outcomes
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What are the different type of outcomes measured in a clinical trial?
- Primary outcome: main outcome and preferably the only one
- Secondary outcome: any other outcomes of interest e.g side effects
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What are some features of an ideal outcome to investigate?
- Relevant
- Valid
- Sensitive
- Specific
- Cheap
Best outcomes should be followed up for a long time but often too expensive
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When in a clinical trial should you measure outcomes?
- Baseline at beginning to look for differences in groups
- During the trial to see if patients are being harmed or disadvantaged
- Final measurement at the end
What are the advantages of random allocation?
- Random allocation allocates participants to treatments fairly, e.g equal number of smokers in each group
- Better with larger studies and historicals that use random allocation can be used
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Why may the clinician or the patient knowing the treatment allocation cause bias in the results?
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What is blinding and the purpose of it in a clincial trial?
- Used to minimise measurement bias, allocation bias and stop patients altering their behaviour
- Difficult to do if treatment is surgical, if two treatments give different side effects or alternative medicine
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