Clinical Trial Flashcards
What is a clinical trial?
Any form of planned experiment which involves patients and is designed to elucidate the most appropriate method of treatment for future patients with a given medical condition.
What is the purpose of a clinical trial?
To provide reliable evidence of treatment efficacy and safety.
What is efficacy?
The ability of a healthcare intervention to improve health of a defined group under specific conditions.
What is safety?
The ability of a healthcare intervention not to harm a defined group under specific conditions.
What is the difference between primary and secondary outcomes?
Primary outcome - preferable only one. Used in the same size calculation.
Secondary outcome - other outcomes of interest. Often includes side effects
What are different types of outcomes?
Patho-physiological -e.g. tumour size
Clinically defined - e.g. death, disease, disability
Patient focused - e.g. quality of life, psychologic well-being, social well-being, satisfaction
What are some features of an ideal outcome?
Appropriate and relevant
Valid and attributable
Sensitive and specific
Reliable and robust
Simple and sustainable
Cheap and timely
What things does a clinical trial need to be to be able to give a fair comparison?
Reproducible - in experimental conditions
Controlled - comparison of interventions
Fair - unbiased without confounding
What are non-randomised clinical trials?
They involve the allocation of patients receiving a new treatment to compare with a group of patients receiving the standard treatment.
But, you get allocation bias and confounding factors.
Why is non-random allocation bad?
Allocation of participants to treatments by a person, historical basis, geographical location, convenience, numerical order ect. leads to the potential for allocation (aka selection) bias and confounding factors to unwittingly cause unidentified differences between the treatment groups being compared.
How do most trials normally allocate patients to groups?
3rd party, computer generated random allocation, accessed by phone / internet.
When is it difficult to make trials blind?
Surgery
Psychotherapy vs antidepressants
Alternative medicines
Lifestyle interventions
Prevention programs
What is ‘confounding’?
a situation in which a measure of the effect of an intervention (or exposure) on an outcome is distorted by the association of that intervention with other factors(s) that influence the outcome.
What is ‘bias’?
systemic distortion in allocation / measurements ect.
What things do you have to consider in a randomised control trial?
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
What is the placebo effect?
Even if the therapy is irrelevant to the patient’s condition, the patient’s attitude to his or her illness, and indeed the illness itself, may be improved by a feeling that something is being done about it.
What is a placebo?
A placebo is an inert substance made to appear identical in every way to the active formulation with which it is to be compared.
How can you minimise less of follow up?
Make the follow-up tactical and minimise inconvenience.
Be honest about the commitment required from participants.
Avoid coercion or inducements.
Maintain contact with participants.
Why might patients not comply with their treatment?
Mis-understood instructions.
Not like taking the treatment.
May think treatment is not working
May prefer another treatment
Can’t be bothered
What is the difference between an explanatory trial and a pragmatic trial?
Explanatory trial - “as-treated” analysis.
Analyses only those who complied with treated so, it compares the physiological effects of the treatment.
BUT, loses effect of randomisation.
Tend to give larger sizes of effect
Pragmatic trial - “intention-to-treat” analysis.
Analyses according to the regional allocation to treatment groups (regardless of if completed follow up or adhered to treatment).
Compares the likely effect of using the treatments in routine clinical practise. ALSO preserves effects of randomisation.
Tend to give small and more realistic sizes of effect.
Clinical trials should normally be analysed on an “intention to treat” basis.
What is clinical equipoise?
Clinical equipoise is the assumption that there is not one ‘better’ intervention present during the design of a randomised controlled trial.
A true state of equipoise exists when one has no good basis for a choice between two or more care options.
What does the research ethics committee focus particularly on?
- Scientific design and conduct of the study
- Recruitment of research participants
- Care and protection of research participants’ confidentiality
- Informed consent process
- Community considerations
