A clinical study involves research using human volunteers (also called participants or subjects) that is intended to add to medical knowledge. There are two main types of clinical studies: clinical trials (also called interventional studies) and observational studies.

In a clinical trial, participants receive specific interventions according to the research plan (protocol) created by the sponsor and investigators. These interventions may be medical products, such as drugs or devices; procedures; or changes to participants’ behaviour, such as diet.

Clinical trials may compare a new medical approach to a standard one that is already available, to a placebo that contains no active ingredients, or to no intervention. Some clinical trials compare interventions that are already available. When a new product or approach is being studied, it is not usually known whether it will be helpful, harmful, or no different than available alternatives (including no intervention).

The drug or treatment under investigation in the clinical trial may be:

  • New and never been tested on people before
  • An existing one being used in a new way

The investigators try to determine the safety and efficacy of the intervention by measuring certain outcomes in the participants. Clinical trials are vital for reliable information about the effects of different treatments, ensuring that treatment options are effective and safe. Before a clinical study can begin, an independent Ethics Committee and if appropriate a Regulatory Authority will evaluate and check that the proposed study is safe, and not likely to cause harm to volunteers. All studies are formally approved prior to any participant enrolling in a trial.

Clinical trials used in drug development are sometimes described by phases. The Heart Lung Centre specialises in delivery clinical trials in early drug development (Phase II and III).

The results of controlled trials help to develop a sound evidence base, which doctors and patients can use when making treatment decisions. In offering a reliable evidence base, doctors can be more confident that they are using treatments that have been shown to have beneficial effects and that resources can be allocated to effective therapies.