It goes without saying that clinical trials are key to advancing all aspects of medicine. At their core, most health trials or studies look at ways to prevent, detect, or treat disease. While there are various study designs to choose from, many fall within two broad categories: interventional or observational.
Interventional trials
An interventional trial is specifically designed to evaluate the direct impacts of treatment or preventative measures on disease. During a randomized controlled trial, which is one example of an interventional trial, participants with the same disease will be randomly separated into one of two or more groups: intervention groups or control groups. Some will be given the intervention, which could be a drug, device, or some other medical intervention (i.e., diet change). Some will not receive the intervention, or will receive the current standard intervention. Both groups are essential to the objectives of a trial, which is to measure the safety and efficacy of whatever drug, device, or other medical intervention is being tested.
Observational studies
During an observational study, no intervention is implemented by the investigator. As the National Cancer Institute explains it, participants are observed or certain outcomes are measured, but no attempt is made to affect the outcome. Which is to say, no treatment is given. One benefit to this approach is the fact that a large population can be studied, over a long period of time, if needed. An observational study could even be a survey in which the investigator is sampling a particular group of people and asking them questions over time.
Key differences
Some key differences between these two research approaches are their aim and organization. The aim of an interventional trial is to get more information about a particular intervention. Participants are organized into different treatment groups so investigators can compare results.
On the other hand, observational studies aim to get more information about populations, diseases, beliefs or behaviors , without any intervention. The investigators observe the participants taking part in the study, but don’t directly influence their treatments or behaviors. They compare differences among disease outcomes, people or populations that emerge from the data. In observational studies investigators do not create groups to compare, they observe and describe groups that already exist.
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