Clinical Trials Flashcards
What is a clinical trial?
The testing of a new medicine or medical device to evaluate whether the drug or device is effective and safe for people to use
Why are drugs tested in clinical trials?
- To allow medical professionals and patients to gain information about the benefits, adverse effects and possible uses of new drugs as well as new ways to use existing drugs
- To translate results of basic scientific research into better ways to prevent, diagnose or treat illness
What are observational studies?
Natural experiments where we observe the progression of patients in the population who are exposed to different drugs and compare outcomes
What is the issue with observational studies?
Those in each group were not randomly allocated so a confounding factor that influences the outcome might also influence the likelihood that a patient received a particular treatment
What is inclusion and exclusion criteria?
Inclusion= the appropriate diagnosis, type and stage of disease, a specific age range, unresponsive to previous treatments Exclusion= medical conditions (renal and hepatic failure), specific drugs that are currently being taken, women of child-bearing potential
Why do clinical trials have these criteria?
Ensure that patients of a particular kind required to address the relevant research question are included
-Ensure that patients who may be exposed to unnecessary risks posed either by any of the treatments are excluded
What are the potential concerns with the criteria?
More criteria imposed= more difficult it is to find subjects, the less likely the trial result will inform real world practice
May bias trial in favour of a better outcome for one of the treatment aims
What are the types of clinical trial design?
- Basic parallel group (two treatments)
- Cross over design (both groups have both treatments , each subject acts as own control so statistical power increased)
What are the features of a good clinical trial?
- Randomisation
- Blinding
- Controls
- Outcome measurement
What is randomisation?
The chances of bias are reduced if subjects are randomly allocated to treatments
Equal groups in terms of potential confounding factors (age, sex, weight, race) in the baseline characteristics
How is variation involved randomising subgroups?
- Stratified= by characteristic
- Blocked= by time
- Clustered= by geographical location
- Methods= telephone/ internet/ envelopes/ coin
What are open label clinical trials?
- Doctor and patient know which drug or vaccine is being administered
- Potential for significant bias, sometimes difficult to conceal allocation from doctor (beta-blockers)
What are the types of blinded clinical trial?
- Single blind= patient doesn’t know
- Double blind= doctor and patient don’t know
Why do you need a control group?
- To assess the impact of any treatment on health, exposed to a comparator treatment
- Diseases get better/ deteriorate over time so impact of treatment can only be estimated compared to a control group
- Inactive placebo/ active control
- Historical controls unreliable
What should the outcome measurement be?
- Objectively measured (not open to interpretation because of bias)
- Clinically relevant (to patients)
- Surrogate end-point, assuming used to extrapolate (long trials)
