There are many terms used to describe the design of clinical trials. There are efforts to reduce inadequate reporting in clinical trial reports and increase transparency thus aiding interpretation, for example the CONSORT Group. Some of the terms used are as follows.
- Superiority study - aims to demonstrate that one treatment is better than another active treatment or a placebo.
- Non-inferiority study - aims to demonstrate that one treatment is not worse than another active treatment within a defined acceptable level of clinical inferiority.
- Equivalence study - aims to demonstrate that two interventions are equivalent to each other within a defined acceptable level of clinical difference.
- Observational - the study watches what happens rather than directly offering interventions.
- Experimental - the study actively provides an intervention, typically this is a randomised controlled trial.
- Randomisation - participants in the study are randomly assigned to treatment groups rather than being selected. This helps to reduce selection bias.
- Retrospective - looks at events that have already happened. This method usually employs healthcare system databases.
- Prospective - looks at what happens to patient populations as time passes.
Level of 'Blinding':
- Open - participants, the clinicians conducting the study and the study assessors all know which intervention group a patient is in.
- Single blind - the participants don't know which intervention group (treatment or placebo) they are in.
- Double blind - neither the participants nor the clinicians conducting the study know which intervention group individual patients are in.
- Triple Blind - neither the participants, the clinicians conducting the study nor the study assessors know which intervention group individual patients are in.
Action: A better understanding of these terms will allow clinicians to interpret the relevance and impact of clinical studies.