In an observational or epidemiological study, researchers do not offer different treatments as part of the research. They study how certain ‘risk factors’ and disease outcomes are related.
Open label trials
In an open label trial, both you and your doctor will know which treatment you are receiving. This is the opposite of a double-blind trial (see blinding).
The term ‘open trial’ may refer to:
A trial that is still recruiting people or following them up. When a trial is closed, it stops recruiting people and following them up. The researchers collect and analyse the results, ready for publication
A trial where the researcher and the participant know which treatment they are receiving – they are not blinded (see blinding). This is usually called an ‘open label’ trial
Outcomes are changes in a participant’s health state. For example an outcome might be that your blood pressure is reduced as a result of taking tablets prescribed by the doctor. Outcome measures are used to measure the effects of a treatment. They might include physical measurements – for example measuring blood pressure, or psychological measurements – for example measuring people’s sense of well-being. If someone takes part in research, they may be asked questions, or may be asked to have extra tests to assess how well the treatment or service has worked.