Clinical Trials Flashcards
(40 cards)
What is the purpose of a clinical trial?
To provide reliable evidence of treatment efficacy + safety
Define clinical trial
Any form of planned experiment which involves patients and is designed to elucidate the most appropriate method of treatment for further patients with a given medical condition
What are the stages in drug development?
What are they testing
- pre-clincal phase: lab studies on cultures + animals | toxicity
- phase 1: volunteer studies | major side effects, pharmacodynamics + pharmacokinetics| < 100 healthy volunteers
- phase 2: treatment studies | dosage + common side effects <1,000 patients
- phase 3: clinical trials | comparison | <10,000 patients
- phase 4: post marketing surveillance | monitor for adverse reactions + new uses
Describe key ethical considerations in trial design + conduct
- trials of new drugs may do harm
- patient must give informed consent
- trial must only be conducted if in clinical equipoise
Advantages of using random allocation to minimise confounding
Randomisation leads to treatment groups that are likely to be similar in size + characteristics
What is clinical equipoise?
The assumption that there is not one better intervention present during design of randomised controlled trial
Disadvantages of using historical control group in non randomised trial
- selection often less well defined
- treated differently from new group
- may be less information about possible bias
- unable to control for confounders
What is a confounder?
A third factor that is associated with the exposure + the outcome which distorts the relationship between them
Factors need of a clinical trial to give a fair comparison
Reproducible
Controlled
Fair
What does randomisation mean?
Whether a participant ends up in the treatment or comparison group is due to chance alone
What is single blind?
One of patient, clinician, assessor does not know which group the patient is in
What is double bind?
Two of patient, clinician, assessor does not know which group the patient is in
What is triple blind?
Everyone does not know which group a patient is in
Examples where blinding is difficult
- surgical procedures
- psychotherapy vs anti depressant
- alternative medicine
- lifestyle interventions
- prevention programmes
Why is allocation concealment important in a randomised controlled trail?
- Without it the recruiter may unconsciously affect who gets enrolled in the trail
- prevents allocation bias (type of selection bias)
What is the purpose of allocation concealment
To hide the randomisation sequence from those recruiting people into the trail
Purpose of randomisation
Distributes confounders equally between groups
What does randomisation prevent?
Confounding
What is the purpose of blinding?
Makes patient, clinical and/or assessor unaware of treatment received
What does blinding prevent?
Bias in how patients act, clinical treat patients or assessors measure outcomes
What are the types of outcome?
Patho-physiological
Clinically defined
Patient-focused
Features of an ideal outcome
- appropriate + relevant
- valid + attributable
- sensitive + specific
- reliable + robust
- simple + sustainable
- cheap + timely
Reasons for pre-defining outcomes
- prevent data dredging, repeated analyses
- have a clear protocol for data collection
- agreed criteria for measurement + assessment of outcomes
What are pre defining outcomes?
Need to define what, when and how outcomes are to be measured before start of clinical trial
