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Clinical Pharmacology > 1.1 Clinical trials > Flashcards

1.1 Clinical trials Flashcards

1
Q

what are barbers principles?

A 
the 4 aims that every prescriber should try and achieve
• Maximise effect 
• Respect patient choice 
• Minimise risk 
• Minimise cost
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2
Q

what can we do to minimise the risk when prescribing?

A
  • Recognise this is a high risk activity - Aim to give the task the attention and focus it deserves
  • Ask for help from the team – pharmacists are your friends!
  • Check Medication History/Allergies, Drug/dose/route/frequency/duration, Interactions and side effects, Correct instructions and monitoring, Local/national guidance/policies
  • Shared decision making
  • Ask the patient to check the prescription and drugs dispensed
  • Double check
  • Non prescription alternatives
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3
Q

what is adherence?

A

voluntary cooperation with taking medications as agreed and prescribed

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4
Q

what is polypharmacy?

A

Still no formally agreed
definition but generally accepted as 4-5
or more drugs being prescribed at once

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5
Q

define a clinical trial?

A

Any form of planned experiment (detailed protocol) which involves patients and is designed to elucidate the most appropriate method of treatment (compare new treatment to old treatment) for future patients with a given medical condition

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6
Q

what is the purpose of a clinical trial?

A

to provide reliable evidence of treatment efficacy and safety

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7
Q

what is efficacy?

A

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

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8
Q

what is meant by the safety of a drug?

A

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

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9
Q

what occurs in the phase I stage of drug development and monitoring?

A

volunteer studies that study the pharmacokinetics (bodys action on drug) the pharmacodynamics ( drugs action on the body) and major side effects of the drug. Less than 100 healthy volunteers.

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10
Q

what occurs in the pre clinical phase of drug development and monitoring?

A

laboratory studies studying the pharmacology and animal toxicology. Uses cell cultures and animals to monitor effects.

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11
Q

what occurs in the phase II stage of drug developme t and monitoring?

A

treatment studies to study the effects and dosages and common-side effects. Less than 1000 patients.

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12
Q

what occurs in the phase III stage of drug development and monitoring?

A

clinical trials. drug must have already proved to have efficacy and safety. New drug is compared with standard treatments. Between 500 to 10,000 patients. Need approval by the MHRA before moving on to phase IV

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13
Q

what occurs in the phase IV stage of drug development and monitoring?

A

post-marketing surveillance. Drug has been through clinical trials and authorised for use by regulatory body (MHRA). Monitoring for adverse reactions and potential new uses. Occurs at a population level.

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14
Q

what is meant by yellow card reporting?

A

Every doctor must report any adverse reactions of a drug in post-marketing surveillance to regulatory body

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15
Q

why are placebo drugs used in clinical trials?

A

If the drug is for treatment of a disease that does not have a routine established treatment for, a placebo is used. This is to allow comparison between a control group (placebo) and an intervention group. The aim of a ‘placebo’ is to cancel out any ‘placebo effect’ that may exist in the active treatment

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16
Q

how do we decide who should take part in clinical trials?

A

inclusion criteria and exclusion criteria. Usually exclude any patients that might be at risk when taking new treatment.

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17
Q

what determines the generalisability of a new drug intervention?

A

the inclusion and exclusion criteria as they determine who the study relates to.

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18
Q

why are outcomes of clinical trials pre-defined?

A

Need to define what, when and how outcomes
are to be measured before start of the clinical
trial:
– prevent ‘data dredging’, ‘repeated analyses’
– have a clear protocol for data collection
– agreed criteria for measurement and assessment of outcomes
stops temptation to show an effect from an intervention.

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19
Q

what is the difference between a primary and secondary outcome?

A 
Primary outcome
– preferably only one primary outcome
– used in the sample size calculation 
Secondary outcomes
– other outcomes of interest
– often includes occurrence of side-effects
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20
Q

what are the 3 types of outcomes?

A

Patho-physiological, e.g. tumour size, thyroxine level, other biomarkers
Clinically defined, e.g. death (mortality), disease (morbidity), disability
Patient-focused, e.g. quality of life, psychological well-being, social well-being, satisfaction

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21
Q

what are the features of an ideal outcome?

A 
appropriate and relevant 
valid and attributable 
sensitive and specific 
reliable and robust 
simple and sustainable 
cheap and timely
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22
Q

when are measurements taken in a clinical trial?

A
  • Baseline measurement of relevant factors
    monitoring for inadvertent differences in groups
  • Monitoring outcomes during the trial
    monitoring for possible effect,
    i.e. is one group being disadvantaged?
    monitoring for adverse effects,
    i.e. are individual patients being harmed?
  • Final measurement of outcomes - comparing final effect of treatments in trial
23
Q

why do we need to show comparability between groups in a clinical trial?

A

to show that the groups are equivalent and therefore that the clinical trial is fair

24
Q

How do we show comparability between groups?

A

by collecting baseline data on

characteristics that we think may relate to both the condition and the outcomes we are investigating.

25
Q

What are the most important ethical considerations for any trial to go ahead? (3)

A

Trials of new drugs may do harm - you should only conduct a trial if you are genuinely in ‘clinical equipoise’ and don’t know what is best treatment for patients.
Patients/participants must understand what participation involves (including known and unknown risks)

26
Q

In order to be able to give a fair comparison of effect

and safety, a clinical trial needs to be:

A
  • Reproducible – in experimental conditions
  • Controlled – comparison of interventions
  • Fair – unbiased without confounding
27
Q

what are non-randomised clinical trials?

A

Non-randomised clinical trials involve the allocation of patients receiving a new treatment to compare with a group of patients receiving the standard treatment

28
Q

what are the disadvantages of non-randomised clinical trials?

A

Allocation bias – by patient, clinician or investigator

Confounding – known and unknown

29
Q

what is a comparison with historical controls?

A

Comparison with historical controls involves the comparison of a group of patients who had the standard treatment with a group of patients receiving a new treatment

30
Q

what are the disadvantages of comparison with historical controls?

A

For the historical controls, the standard treatment group:
• selection often less well defined, less rigorous
• unable to control for confounders
• treated differently from ‘new treatment’ group
• there may be less information about potential bias/confounders

31
Q

what are the advantages of random allocation/randomisation?

A

Allocate participants to the treatments fairly
• Minimal allocation bias – randomisation gives each participant an equal chance of being allocated to each of the treatments in the trial • Minimal confounding – in the long run, randomisation leads to treatment groups that are likely to be similar in size and characteristics by chance.
- removes the investigator so that they do not influence the randomisation

32
Q

how do most trials do randomisation?

A

3rd party, computer generated random allocation, accessed by phone/internet

33
Q

what is stratified randomisation?

A

to put in certain rules when doing randomisation to guarantee clinical groups are more comparable. Useful in smaller participation trials

34
Q

what is block randomisation?

A

Random allocation can be made in blocks in order to keep the sizes of treatment groups similar. In order to do this you must specify a sample size that is divisible by the block size you choose. In turn you must choose a block size that is divisible by the number of treatment groups you specify.

35
Q

what are the disadvantages of open label treatment in a clinical trial?

A

Knowledge of which participant is receiving which treatment may bias the results of a clinical trial, e.g.
– Patient may alter their behaviour, other treatment, or
even expectation of outcome (behaviour effect)
– Clinician may alter their treatment, care and interest
in the patient (non-treatment effect)
– Investigator may alter their approach when making
measurements and assessing outcomes (measurement bias)

36
Q

what is the advantage of blinding?

A

Remove allocation bias – by ensuring that randomisation gives each participant an equal chance of being allocated to each of the treatments in the trial

37
Q

what are the different types of blinding?

A
  • Single blind – one of patient, clinician, assessor does not know the treatment allocation (usually patient)
  • Double blind – two of patient, clinician, assessor does not know the treatment allocation (usually patient + clinician /assessor)
  • Triple blind (term rarely used as ‘double blind’ usually implies all do not know the allocation)
38
Q

how are blindings done?

A

Aim to make the treatments appear identical in every way, e.g. appearance, taste, texture,
dosage regimen, warnings
Use a designated pharmacy to label identical containers for the treatments with code numbers, and to have a code sheet detailing which code
number corresponds to which treatment

39
Q

what is a confounding factor?

A

a factor that is associated with the disease AND the outcome of interest, and this association is separate to the relationship between the risk factor (or intervention) being investigated.

40
Q

what is a bias?

A

systematic distortion in allocation/measurement etc.

41
Q

what is a placebo?

A

A placebo is an inert substance made to appear identical in every way to the active formulation with which it is to be compared, e.g. appearance, taste, texture, dosage regimen, warnings, etc.

42
Q

what can be done to minimise losses to follow up?

A

Make the follow-up practical and minimise inconvenience
Be honest about the commitment required from
participants
Avoid coercion or inducements
Maintain contact with participants

43
Q

what can we do to maximise adherence to a treatment?

A
  • Simplify the instructions
  • Ask about adherence
  • Ask about effects and side-effects
  • Monitor adherence, e.g. tablet count, urine level, blood level
  • Understand it is never possible to achieve 100% adherence
44
Q

what is an explanatory trial?

A

An efficacy study, only considers the patients that adhered to the treatment and completed follow up. Removes randomisation so non-compliers are likely to be systematically different from compliers (selection bias and confounding). Compares the physiological action of the treatments only

45
Q

what is a pragmatic trial?

A

allows us to compare the treatments in routine clinical practice by including patients that did not adhere or complete follow up. If you are in the study you are analysed regardless of whether you took the treatment. Preserves effects or randomisation.

46
Q

what factors need to be considered in planning a randomised control trial?

A 
– The disease of interest
– The treatments to be compared
– The outcomes to be measured
– Possible bias and confounders
– The patients eligible for the trial
– The patients to be excluded from the trial
47
Q

what steps are involved when conducting a randomised control trial?

A
  • Identify a source of eligible patients
  • Invite eligible patients to be in the trial
  • Consent patients willing to be in the trial
  • Allocate participants to the treatments fairly, i.e. without bias or confounding
  • Follow-up participants in identical ways
  • Minimise losses to follow-up
  • Maximise compliance with treatments
48
Q

what issues need to be considered for a clinical trial to be ethical?

A
  • Clinical equipoise
  • Scientifically robust
  • Ethical recruitment
  • Valid consent
  • Voluntariness
49
Q

how do individual and collective ethics differ in RCTs?

A 
• Collective Ethic:
– RCTs aim to properly test treatments for efficacy and safety 
• Individual Ethic:
– RCTs do not guarantee benefit 
– RCTs may result in harm 
– RCTs allocate treatment by chance 
– RCTs place burdens and confer benefits
50
Q

what is clinical equipoise?

A

Clinical equipoise is when there is reasonable uncertainty or genuine ignorance about the better treatment or intervention (including non- intervention)

51
Q

how do we ensure that a clinical trial is scientifically robust?

A

• Addresses a relevant or important issue
• Asks a valid question
• Has an appropriate study design and protocol (addressing potential biases and confounding)
• Has the potential to reach sound conclusions (minimising inability to find a clinically important effect using a sample size calculation)
• Can justify the use of the comparator treatment
or placebo (‘Declaration of Helsinki’ 2000, paragraph 29)
• Has acceptable risks of possible harm compared to anticipated benefits
• Has provision for monitoring the safety and well-being of participants in the trial (e.g. data monitoring, patient monitoring)
• Has arrangements for appropriate reporting and
publication

52
Q

what is voluntariness?

A

Voluntariness is a pre-requisite for consent to be
valid, i.e. the decision should be free from coercion or manipulation or the perception that coercion or manipulation may take place

53
Q

what is the focus of the research ethics committee in a RCT?

A
  1. Scientific design and conduct of the study
  2. Recruitment of research participants
  3. Care and protection of research participants
  4. Protection of research participants’ confidentiality
  5. Informed consent process
  6. Community considerations

Clinical Pharmacology (26 decks)

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