L2 Clinical Trials Flashcards

1
Q

Clinical trial

A

Planned experiment which involves patient’s and is designed to elucidate the most appropriate method of treatment for future patients with a given medical condition

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2
Q

Efficacy

A

Ability of an intervention to improve the health of a defined group under specific conditions

Aka effect

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3
Q

Safety

A

The ability of a health care intervention not to harm a defined group under specific conditions

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4
Q

Goals of clinical trial

A

Reproducible
Controlled - comparison of intervention
Fair - Unbias without confounding

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5
Q

Difference between efficacy and effectiveness

A

Effectiveness is the effect in real world clinical experience where as efficacy is in ideal condition

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6
Q

Stages in drug development and monitoring

A

Phase I

  • volunteer studies
  • assessing pharmacodynamics, pharmacokinetics and side effects
  • healthy volunteers (controlled)

Phase II

  • treatment studies
  • effects and dosage - therapeutic window
  • common side effects
  • patients

Phase III

  • clinical trials
  • COMPARISON with standard treatment
  • patients

Phase IV

  • post marketing surveillance
  • monitoring for adverse side effects
  • potential for new uses
  • whole population
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7
Q

Disadvantages of a non randomised clinical trial

A

Allocation bias - by patient, clinician or investigator

Confounding - known and unknown

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8
Q

Disadvantages of comparison with histological controls

A

Condition may have changed from the past
Population factors change with time
Different hospitals may have different protocols
Selection of histological controls are less rigorous
Histological controls were probably treated differently from new treatment group
Less information about potential bias of con founders

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9
Q

Steps involved in an RCT

A
  1. Definition of key study variables
  2. Clinical trial
  3. Compare outcomes
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10
Q

Defining the key variables

A

Define the:

  • disease of interest
  • patient eligible for the trial
  • patients excluded from trial e.g. disease too advanced
  • treatment to be compared
  • outcomes to be measured e.g. adherence, hospital admission etc.
  • possible bias or confounders
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11
Q

How to conduct a trial

A
Identify a source of eligible patients 
Invite those eligible 
Consent patients 
Allocate participants randomly 
Follow up patients 
Minimise losses to follow up 
Maximise adherence to treatments
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12
Q

Comparison of outcomes

A

Is there an observed difference
Statistically significant
Is the difference clinically significant
Was the design of the trial and conduct good

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13
Q

95% confidence interval

A

If the null hypothesis is within the 95% confidence interval, the results may be due to chance

P > 0.05

Therefore not statistically significant

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14
Q

Observed ratio of 0.87 meaning

A

Reduction of 13%

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15
Q

Sample size effect on confidence interval

A

Larger sample size, decreases the confidence interval

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16
Q

Why are outcomes predefined

A

Need to define what, when and how outcomes are measure before the clinical trial to:

  • prevent repeated analyses
  • define protocol for data collection
  • agreed criteria for measurement and assessment of outcomes
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17
Q

Primary outcome

A

Most important outcome of interest e.g. mortality
Preferably 1 primary outcome
Used in the sample size calculation

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18
Q

Secondary outcomes

A

Other outcomes of interest

E.g. side effects or occurrence or quality of life

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19
Q

Types of outcomes

A

Pathophysiological:

  • tumour size
  • thyroxine levels
  • ECG changes

Clinically defined:

  • mortality
  • disease
  • disability

Patient focused:

  • QoL
  • psychological well-being being
  • social well being
  • satisfaction
20
Q

Features of an ideal outcome

A
Appropriate and relevant 
Valid and attributable 
Sensitive and specific 
Reliable and robust 
Simple and sustainable 
Cheap and timely
21
Q

Timing of measurements

A

Baseline:
- monitor for inadvertent differences in groups

During trial:

  • possible effects - is one group more disadvantaged
  • Adverse effects

After trial
- comparing final effect of treatment

22
Q

Types of allocation

A

Non random allocation
Random allocation
Knowing the treatment allocation
Blinding

23
Q

Disadvantages of knowing the treatment allocation

A

Knowledge of which patient is getting which treatment

  • participant bias - behaviour effect
  • clinician may alter their treatment - non treatment effect
  • investigator may alter their approach when assessing outcomes - measurement bias
24
Q

How to limit bias

A

Allocation bias - random allocation
Recall bias - use pathophysiological or clinical outcomes e.g. mortality
Observer bias - double blind

25
Single blind
1 of patient, clinician or investigator doesn’t know which treatment they’re receiving
26
Double blind
2 of patient, clinician or investigator doesn’t know allocation
27
Triple blind
All do not know treatment allocation
28
Placebo effect
A patient acts differently because of the treatment they receive Therefore provide a placebo as a control to cancel out the placebo effect
29
Disadvantage of comparing treatment with no treatment
Do not know whether outcome is due to treatment or that one group received care
30
Ethical implications of a placebo
Should only be used when no treatment is available Placebo is a form of deception Important that participants are informed that they may receive the placebo
31
Losses to follow up
Not every participant remains in the trial as: - their condition may make it necessary to be removed from the trial - May choose to withdraw from the trial - die before trial ends
32
How to minorities loss to follow up
- make follow up practical and minimise inconvenience - honest about commitment required - maintain contact with participants
33
Non compliance with treatment reasons
- misunderstood instructions - May not like taking treatment - May think treatment isn’t working - prefer to take another treatment - can’t be bothered
34
Reduce non compliance
- simplify instructions - ask and monitor compliance - ask about effects or side effects
35
Difference between explanatory and pragmatic trial
Explanatory - ‘as treated’ analysis - ignores participants that do not take treatment or loss to follow up - biologists - new treatment vs standard treatment - compares physiological effects of the treatment - larger sizes of effect Pragmatic - ‘intention to treat’ analysis - includes non treated - medics - new treatment and not take new treatment vs standard treatment and not take standard treatment - compares effects of use of treatment routinely - preserves randomisation - smaller more realistic sizes of effect
36
Disadvantage of explanatory as treated trials
Loss of randomisation as those that do not comply are likely to be systemically different from compilers - selection bias - confounding
37
Declaration of Helsinki
Health of the patient is the upmost priority | Act only in the patients interest
38
Collected ethic
All patients should have treatments that are properly tested for efficacy and safety - RCTs aim to properly test treatment for efficacy and safety
39
Individual ethic
Beneficence Non maleficence Autonomy Justice ``` RTCs do not guarantee benefit May result in harm Allocate treatment by chance (justice) Place burdens and confer benefits Benefit future patients ```
40
Issues considered in an ethical trial
``` Clinical equipoise - reasonable uncertainty or ignorance about better treatment or intervention Scientifically robust Ethical recruitment Valid consent Voluntariness and right to withdraw ``` Therefore approval from an ethics committee
41
Scientifically robust
- addresses relevant or important issue - ask valid questions - appropriate study design and protocol - ability to find clinically important effect - acceptable risks compared to anticipated benefits - justify use of placebo - provisions for monitoring the safety and well being of patients - provisions for appropriate reporting and publication
42
Ethical recruitment
Do not use: - Participants from communities that are not likely to benefit e.g. cannot test AIDs drug trials in developing world countries - inappropriate use of participants with high risk of harm compared to benefits e.g. pregnant ladies - participants likely to be excluded form analysis Do not exclude: - people who differ from homogenous group e.g. non white people - people who are difficult to get valid consent from e.g. mentally ill
43
Valid consent
``` Knowledgable informant Appropriate information - verbal and written - thinking period - right for withdrawal ``` Participant: Informed Competent decision maker Legitimate authoriser Signed consent form as evidence for valid consent
44
Voluntariness
Needed for consent to be valid | Free from manipulation or coercion
45
Research committee
``` Research governance - design and conduct of study - recruitment of participants - care and protection of participants - confidentiality - informed consent - community considerations Financial management Resource implications ``` Insure dignity, rights, safety and well being of participants is adhered to primarily