Study Designs : Intervention Studies Flashcards
How does an analytical study differ from an interventional study?
In an interventional study the researcher has control over the allocation of the study subjects to the groups being compared
What are two examples of intervention studies?
- Clinical trials
- Field trials
What is considered to be the gold standard of a clinical trial?
A randomised clinical trial
What is a therapeutic trial?
Trials conducted amongst individuals with a particular disease to assess the effectiveness of an agent or procedure to diminsh symptoms, prevent recurrence, or reduce mortality
What is a preventative trial?
These trials are conducted to evaluate whether an agent or procedure reduces the risk of developing a particular disease among individuals free from that disease at the beginning of the trial.
Preventative trials may be conducted amongst individuals or among entire communities
What is a phase I clinical trial?
Initial studies to determine the metabolism and pharmacologic actions of drugs in humans, the side effects
associated with increasing doses, and to gain early evidence of effectiveness; may include healthy participants and/or patients
Tested in a small group of people (8-80) to evaluate its safety and to explore possible side effects and the doses at
which they occur.
What is phase II of a clinical trial?
“Controlled clinical studies conducted to evaluate the effectiveness of the drug for a particular indication or
indications in patients with the disease or condition under study and to determine the common short-term side effects and risks
*Tested in larger groups (80-200) to get more information about effectiveness and potential side effects at different
dosages. *
What is phase III of a clinical trial?
“Expanded controlled trials after preliminary evidence suggesting effectiveness of the drug has been obtained
and are intended to gather additional information to evaluate the overall benefit-risk relationship of the drug and provide an
adequate basis for physician labelling.“
Tested in larger groups (00’s to 000’s) to formally test effectiveness and establish the frequency and severity of side
effects compared to no treatment or compared to currently used treatments (“usual care”)
What is phase IV of a clinical trial?
refers to post-marketing “surveillance” to collect information regarding risks, benefits, and optimal use. This phase can
be particularly important for identifying rare, but potentially devastating side effects
What are the key characteristics of an intervention study?
- They specify intervention
- Animals grouped by researcher according to the intervention into
intervention/treatment or control group - Follow-up and compliance
- Can either be single/double blind or everyone knows
Why may you conduct an intervention study?
to test efficacy against no treatment; to compare to an existing
treatment & demonstrate equivalence; to compare to an existing product and demonstrate superior performance
Clinical improvement, change in a clinical test parameter, survival, time to recovery etc.
What are some potential limitations of intervention studies?
- Studies may be expensive, time and resource intensive
- results of clinical trials may not be repeatable in a ‘real world’ setting
- Informed consent and ethics issues
- sample size must be adequate to detect important differences between groups
What is the purpose of randomisation in terms of groups?
Makes them comparable, they will be at similiar baselines and therefore there is a decreased chance of counfounding variables having an effect
