Adverse event - An unexpected medical problem that happens during the clinical trial that may or may not be caused by the investigational treatment. Also referred to as an adverse effect. - The U.S government website that provides the public with access to summary information about ongoing and completed clinical trials.

Control group - The group of participants in the clinical trial that does not receive the investigational treatment being studied. This group is compared to the group that receives the investigational treatment, to see if the investigational treatment works.

Blinding (Double-blind trial) - A type of clinical trial in which neither the participants nor the researcher knows which treatment or intervention participants are receiving until the clinical trial is over. This means that the results are less likely to be biased, i.e. affected by factors that are not related to the investigational treatment being tested.

Eligibility criteria (Inclusion/exclusion criteria) – A list of characteristics in a clinical protocol that must be shared by all trial participants. The criteria are different for each study, but typically include age, gender, biological sex, medical history and current health status. 

Enrollment - The process of registering or entering a patient into a clinical trial. 

EMA – The European Medicines Agency, an agency of the European Union responsible for the evaluation and supervision of medicines in the European Union.

FDA - The Food and Drug Administration, an agency in the U.S. responsible for protecting the public health by ensuring the safety, efficacy and security of human drugs, biological products and medical devices.

Healthy volunteer – A person with no known health problems who participates in research to test an investigational drug, device or therapy.

Informed consent form - A document that provides persons with the information they need to make an informed decision about participating in a clinical trial. 

Interventional trial - A type of trial in which participants are assigned to groups that receive one or more intervention/treatment (or no intervention) so that researchers can evaluate the effects of the interventions.

Observational trial - A type of trial in which participants are observed or certain outcomes are measured. There is no intervention, meaning no investigational treatment is given.

Open-label trial - A type of trial where both the trial staff and the participants know which investigational or approved drug or treatment is being given.

Patient volunteer - A person with a particular disease or condition who volunteers to take part in a clinical trial also known as a participant.

Placebo - An inactive substance that looks like and is given the same way as the investigational drug or treatment being tested but does not include the active ingredient.

Protocol - A document that describes how a clinical trial will be run (the objective(s), design, and organization of a clinical trial) and ensures the safety of the trial participants and integrity of the data collected.

Randomized [clinical trial] - A trial in which the participants are divided by chance into separate groups that compare different investigational, placebo or approved treatments or interventions. 

Trial status - A description of trial that details if it has begun, is in process, is on hold, has been stopped or has completed.

Examples of trial status as defined on

  • Not yet recruiting: Participants are not yet able to be enrolled in the clinical trial

  • Recruiting: Participants are currently able to be enrolled in the clinical trial

  • Enrolling: Participants are being (or will be) selected from a predetermined population

  • Active, not recruiting: Trial is continuing, meaning participants are receiving an intervention or being examined, but new participants are not currently being enrolled

  • Completed: The trial has concluded normally; the last participant’s last visit has occurred

  • Suspended: Trial stopped early but may continue

  • Terminated: Trial stopped early and will not continue; participants are no longer receiving an intervention or being examined

  • Withdrawn: Trial stopped early, before enrollment of first participant

Trial endpoint / outcome – A data result that can be measured to determine whether or not the goals of the trial have been reached and if the investigational intervention being studied is beneficial or not. 

Trial site - The physical location where trial is conducted.