Clinical Trials Flashcards

1
Q

What is a clinical trial?

A

Any form of planned experiment which involves patients and is designed to elicidate the most appropriate method of treatment for future patients with a medical condition

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2
Q

What are the 2 main purposes of a clinical trial?

A

To provide reliable evidence of treatment efficacy & safety

Efficacy: ability of intervention to improve the health of a defined group under specific conditions

Safety: ability of intervention not to harm a defined group under specific conditions

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3
Q

What 3 things must a clinical trial be in order to give a fair comparison of effect and safety?

A
  1. Reproducible - in experiemental conditions
  2. Controlled - comparison of interventions to show it is the intervention that’s made the difference
  3. Fair - unbiased without confounding
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4
Q

What is the difference between efficacy and effectiveness?

A

Efficacy = ideal clinical conditions

Effectiveness = real world clinical experience

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5
Q

What are the 4 different phases of a clinical trial?

A
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6
Q

What are non-randomised clinical trials?

A

Clinical trials involving the allocation of patients recieving a new treatment to compare with a group of patients recieving the standard treatment

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7
Q

What are the disadvantages of non-randomised clinical trials?

A

Allocation bias - by patient, clinician or investigator

Confounding - known and unknown

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8
Q

What are comparison with historical controls?

A

Comparison of a group of patients who had the standard treatment with a group of patients recieving new treatment

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9
Q

What are the disadvantages of using comparison of historical controls for the ‘standard treatment’ group?

A
  • Selection less rigorous
  • treated differently from ‘new treatment’ group
  • less information about bias/ confounders
  • unable to control for confounders
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10
Q

Is this observed rate ratio statistically significant? Explain why

A

NO

The observed rate ratio and confidence interval crosses 1 therefore an affect may be due to chance

1= no effect at all

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11
Q

For what reasons do you need to pre-define trial outcomes at the start of the trial?

A
  • prevent ‘data dredgind’, ‘repeated analyses’
  • protocol for data collection
  • agree criteris for measurement and assessment of outcomes
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12
Q

What is the difference between primary and secondary outcomes?

A

Primary Outcomes:

  • Only one primary outcome
  • Used in the sample size calculation

Secondary Outcomes:

  • other outcomes of interest
  • often includens occurence of side effects
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13
Q

What are the 3 different types of trial outcome?

A

Patho-physiological

  • tumour size, thyroixine levels, ECG changes

Clinically defined

  • death (mortality)
  • disease (morbidity)
  • disability

Patient-focused

  • QoL
  • psychological well-defined
  • social well being
  • satisfaction
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14
Q

What are the features of an ideal trial outcome?

A
  • Appropriate and Relevant
  • Valid and attributable (linked to the treatment compared)
  • Sensitive and Specific
  • Reliable and Robust
  • Simple and Sustainable
  • Cheap and Timely
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15
Q

How are measurements timed throughout a clinical trial?

A
  • Baseline measurement taken of relevant factors
  • Monitoring during the trial
    • for possible effect
    • for adverse effects
  • Final measurement of outcomes
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16
Q

What are the benefits of random allocation in a trial?

A
  • Minimal allocation bias
    • Each participant has an equal chance of being allocated to the treatments in the trial
  • Minimal confounding
    • treatment groups likely to be similar in size and characteristics by chance
17
Q

What is the best way to randomise a trial?

A

Use an external unit to create a computer generated random number that is accessed remotely

18
Q

What are the disadvantages of open label trials (knowing the treatment allocation)?

A
  • Patient may alter behaviour or expectations of outcome (behaviour effect)
  • Clinician may alter their treatment, care and interest in patient (non-treatment effect)
  • Investigator may alter their approach when making measurements and assessing outcomes (measurement bias)
19
Q

What are the different types of blinding of a trial?

A

Single-blind - one of; patient, clinician or assessor does not know treatment

Double-blind - two of; patient, clinican or assessor does not know the treatment allocation

Triple blind - implies all do not know the allocation

20
Q

Give examples of when blinding a trial may be difficult?

A
  • Surgical procedures
  • Pychotherapy vs anti-depressants
  • Using alternative medicine
  • Lifestyle interventions
  • Prevention programmes
21
Q

What is the placebo effect?

A

Even if the therapy is irrelevant to the patients condition, the patient’s attitude to their illness or the illness itself may be improved by a feeling that something is being done about it

22
Q

What is a placebo?

A

An inert substance made to appear identical in every way to the active formulation with which it is to be compared

23
Q

Explain what it means that active treatment has placebo in it?

A

Giving any kind of treatment has placebo effect

By comparing with a placebo, it cancels out the placebo effect that exists within active treatment

24
Q

What are some of the ethical implications of placebo?

A
  • should only be used when no standard treatment is available
  • Use of placebo is a form of deception
  • Essential all participants are informed that they may recieve a placebo
25
What is meant by losses to follow up?
Not every participant will remain in the trial * Their clinical condition may be necessitate their removal from the trial (appropriate) * They may choose to withdraw from trial (unfortunate)
26
How can you minimise losses to follow up?
* Make follow up practical and minimise inconvenience * Be honest about commitment required from participants * Avoid Coercion * Maintain contact with paticipants
27
Why may patients not comply with their allocated treatment?
* Mis-understood instructions * May not like taking their treatment * May think it's not working * May prefer other treatments * Can't be bothered
28
How can you maximise compliance in a trial?
* Simplify instructions * Ask about compliance * Ask about effects/ side effects * Monitor compliance; tablet count, urine level, blood level
29
What is 'as treated analysis'
Only the patients who have taken their treatment allocation **as indicated** are measured in final analysis Only interested in the physiological effect of drug on body
30
What is 'intention-to-treat' analysis?
**Everyone** is analysed, regardless of whether they took the drug or not Reflects **real life** practice
31
What are the disadvantages of 'as-treated' analysis?
* **Loses the effect of randomisation** * Non compliers likely to be systemically different from compliers * Introduced selection bias and confounding
32
What is the main benefit of 'intention to treat' analysis?
**Preserves the effect of randomisation** Minimal selection bias and confounding
33
What is the difference between collective and individual ethics?
**Collective:** * All patients should ahve treatments that are properly tested for efficacy and safety **Individual:** * Priniciple of beneficence * principle of non-maleficence * principle of autonomy * principle of justice
34
What is clinical equipoise?
When there is reasonable **uncertainty** or gernuine **ignorance** about the better treatemtn of intervention (including non-intervention)
35
What are the roles of reseatch ethics committee?
Focus on: * Scientific design and conduct of the study * Recruitment of research participants * Care and protection of research participants * Protction of research participant's confidentiality * Informed consent process * Community considerations