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Flashcards in L2 Clinical Trials Deck (45)
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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

2
Q

Efficacy

A

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

Aka effect

3
Q

Safety

A

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

4
Q

Goals of clinical trial

A

Reproducible
Controlled - comparison of intervention
Fair - Unbias without confounding

5
Q

Difference between efficacy and effectiveness

A

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

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
7
Q

Disadvantages of a non randomised clinical trial

A

Allocation bias - by patient, clinician or investigator

Confounding - known and unknown

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

9
Q

Steps involved in an RCT

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

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

14
Q

Observed ratio of 0.87 meaning

A

Reduction of 13%

15
Q

Sample size effect on confidence interval

A

Larger sample size, decreases the confidence interval

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
17
Q

Primary outcome

A

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

18
Q

Secondary outcomes

A

Other outcomes of interest

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

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
Q

Single blind

A

1 of patient, clinician or investigator doesn’t know which treatment they’re receiving

26
Q

Double blind

A

2 of patient, clinician or investigator doesn’t know allocation

27
Q

Triple blind

A

All do not know treatment allocation

28
Q

Placebo effect

A

A patient acts differently because of the treatment they receive
Therefore provide a placebo as a control to cancel out the placebo effect

29
Q

Disadvantage of comparing treatment with no treatment

A

Do not know whether outcome is due to treatment or that one group received care

30
Q

Ethical implications of a placebo

A

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
Q

Losses to follow up

A

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
Q

How to minorities loss to follow up

A
  • make follow up practical and minimise inconvenience
  • honest about commitment required
  • maintain contact with participants
33
Q

Non compliance with treatment reasons

A
  • misunderstood instructions
  • May not like taking treatment
  • May think treatment isn’t working
  • prefer to take another treatment
  • can’t be bothered
34
Q

Reduce non compliance

A
  • simplify instructions
  • ask and monitor compliance
  • ask about effects or side effects
35
Q

Difference between explanatory and pragmatic trial

A

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
Q

Disadvantage of explanatory as treated trials

A

Loss of randomisation as those that do not comply are likely to be systemically different from compilers

  • selection bias
  • confounding
37
Q

Declaration of Helsinki

A

Health of the patient is the upmost priority

Act only in the patients interest

38
Q

Collected ethic

A

All patients should have treatments that are properly tested for efficacy and safety

  • RCTs aim to properly test treatment for efficacy and safety
39
Q

Individual ethic

A

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
Q

Issues considered in an ethical trial

A
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
Q

Scientifically robust

A
  • 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
Q

Ethical recruitment

A

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
Q

Valid consent

A
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
Q

Voluntariness

A

Needed for consent to be valid

Free from manipulation or coercion

45
Q

Research committee

A
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