Clinical trial terms
Understand common clinical trial terms used on Health Trials.
Sponsors/Collaborators
This shows who is responsible for the trial and making sure all trial information is correctly reported and updated. In some cases, the sponsor can assign a lead researcher or doctor to be responsible for the trial, as long as they have full control of the trial.
Collaborator
Other organizations that help with the trial, for example by providing funding, expertise, or support with running or analyzing the trial.
Principal Investigator
The main doctor or researcher in charge of running the trial and making sure it is carried out properly.
Sponsor
The person or organization that starts and manages the trial. They are responsible for planning, funding, and overseeing the research.
Sponsor-Investigator
A person who both starts the trial and is also responsible for running it.
| Term | Description |
|---|---|
| Collaborator | Other organizations that help with the trial, for example by providing funding, expertise, or support with running or analyzing the trial. |
| Principal Investigator | The main doctor or researcher in charge of running the trial and making sure it is carried out properly. |
| Sponsor | The person or organization that starts and manages the trial. They are responsible for planning, funding, and overseeing the research. |
| Sponsor-Investigator | A person who both starts the trial and is also responsible for running it. |
Trial status
The trial status shows whether a trial is currently looking for participants.
Active, not recruiting
The trial is still ongoing, but no longer accepting new participants. People who have already joined continue in the trial.
Approved for marketing
The treatment has been approved and is available for use. The trial is no longer recruiting participants.
Available
The treatment may be available to eligible patients. Contact the trial team to learn if you qualify.
Completed
The trial has ended as planned. No new participants can join at this stage.
Enrolling by invitation
The trial is only open to people who are invited by the trial team.
No longer available
The trial is no longer available for participation.
Not yet recruiting
The trial is not yet open for participation.
Recruiting
The trial is currently looking for participants. If you meet the criteria, you may be able to join.
Suspended
The trial has been temporarily paused. No new participants can join right now, but the trial may start again later.
Temporarily not available
The treatment or trial is temporarily unavailable. It may become available again in the future.
Terminated
The trial ended earlier than planned and will not continue. Participants can no longer join.
Unknown
The current trial status has not been updated or cannot be confirmed.
Withdrawn
The trial was stopped before any participants joined.
Withheld
Information about the trial status is not publicly available.
| Term | Description |
|---|---|
| Active, not recruiting | The trial is still ongoing, but no longer accepting new participants. People who have already joined continue in the trial. |
| Approved for marketing | The treatment has been approved and is available for use. The trial is no longer recruiting participants. |
| Available | The treatment may be available to eligible patients. Contact the trial team to learn if you qualify. |
| Completed | The trial has ended as planned. No new participants can join at this stage. |
| Enrolling by invitation | The trial is only open to people who are invited by the trial team. |
| No longer available | The trial is no longer available for participation. |
| Not yet recruiting | The trial is not yet open for participation. |
| Recruiting | The trial is currently looking for participants. If you meet the criteria, you may be able to join. |
| Suspended | The trial has been temporarily paused. No new participants can join right now, but the trial may start again later. |
| Temporarily not available | The treatment or trial is temporarily unavailable. It may become available again in the future. |
| Terminated | The trial ended earlier than planned and will not continue. Participants can no longer join. |
| Unknown | The current trial status has not been updated or cannot be confirmed. |
| Withdrawn | The trial was stopped before any participants joined. |
| Withheld | Information about the trial status is not publicly available. |
Trial phase
The trial phase shows how far along a treatment is in testing, from early research to large trials and follow-up trials after approval.
Early Phase 1
An initial, small trial in humans. The focus is to explore how the body responds, often using very low doses. It is not intended to treat or diagnose a condition.
N/A
This trial has no formal phase. This is common for trials of devices, procedures, or behavioral trials.
Phase 1
The first step of testing a treatment in people. The focus is on safety, side effects, and how the body responds to the treatment.
Phase 1/2
A combined trial that looks at both safety and effectiveness.
Phase 2
A combined trial that is testing how well a treatment works and continues to test it in larger groups to confirm the results.
Phase 2/3
A combined trial that is testing how well a treatment works and continues to test it in larger groups to confirm the results.
Phase 3
A large trial that checks how well a treatment works and how safe it is by comparing it to standard care or no treatment (placebo).
Phase 4
A trial done after treatment is approved. The focus is to see how the treatment works over time in everyday use, including long term benefits and safety.
| Term | Description |
|---|---|
| Early Phase 1 | An initial, small trial in humans. The focus is to explore how the body responds, often using very low doses. It is not intended to treat or diagnose a condition. |
| N/A | This trial has no formal phase. This is common for trials of devices, procedures, or behavioral trials. |
| Phase 1 | The first step of testing a treatment in people. The focus is on safety, side effects, and how the body responds to the treatment. |
| Phase 1/2 | A combined trial that looks at both safety and effectiveness. |
| Phase 2 | A combined trial that is testing how well a treatment works and continues to test it in larger groups to confirm the results. |
| Phase 2/3 | A combined trial that is testing how well a treatment works and continues to test it in larger groups to confirm the results. |
| Phase 3 | A large trial that checks how well a treatment works and how safe it is by comparing it to standard care or no treatment (placebo). |
| Phase 4 | A trial done after treatment is approved. The focus is to see how the treatment works over time in everyday use, including long term benefits and safety. |
Trial type
The trial type describes how the research is done, whether participants are given a treatment or simply observed.
Expanded Access
A way for some patients who cannot join a clinical trial to get access to an experimental treatment. This is only for special cases and is not part of a research trial.
Interventional
A trial where participants are given a treatment or intervention to see how it affects their health.
Observational
A trial where researchers simply observe and record what happens. They do not assign any treatment or change care. Instead, they collect information to better understand health patterns and outcomes.
Pivotal trial
Typically a phase 3 clinical trial, designed to show whether a treatment works and is safe enough for approval by health authorities.
| Term | Description |
|---|---|
| Expanded Access | A way for some patients who cannot join a clinical trial to get access to an experimental treatment. This is only for special cases and is not part of a research trial. |
| Interventional | A trial where participants are given a treatment or intervention to see how it affects their health. |
| Observational | A trial where researchers simply observe and record what happens. They do not assign any treatment or change care. Instead, they collect information to better understand health patterns and outcomes. |
| Pivotal trial | Typically a phase 3 clinical trial, designed to show whether a treatment works and is safe enough for approval by health authorities. |
Other terms
These terms describe common features, methods, and measurements used in clinical trials.
Adverse events
Any unwanted health problems that occur during a trial, whether or not they are caused by the treatment.
Arm/trial group
A group of participants in a trial who receive the same treatment or care.
Blinded trial
A trial where participants do not know which treatment each person receives, to keep results unbiased.
Double blinded
When both participants and researchers do not know which treatment each person receives, to keep results unbiased.
Eligibility criteria
The requirements a person must meet to join a trial, such as age, condition, or medical history.
Enrollment/sample size
The number of people who are planned to take part in the trial.
Intervention
The treatment, procedure, or test being studied.
Placebo
A substance or treatment with no active medicine, used for comparison to see if the real treatment works.
Primary endpoint/outcome
The main result the trial is designed to measure, such as whether a treatment improves symptoms or slows disease.
Protocol
The detailed plan for how the trial is conducted, including who can join, what treatments are given, and what is measured.
Randomized
Participants are assigned to different treatments by chance, like flipping a coin.
| Term | Description |
|---|---|
| Adverse events | Any unwanted health problems that occur during a trial, whether or not they are caused by the treatment. |
| Arm/trial group | A group of participants in a trial who receive the same treatment or care. |
| Blinded trial | A trial where participants do not know which treatment each person receives, to keep results unbiased. |
| Double blinded | When both participants and researchers do not know which treatment each person receives, to keep results unbiased. |
| Eligibility criteria | The requirements a person must meet to join a trial, such as age, condition, or medical history. |
| Enrollment/sample size | The number of people who are planned to take part in the trial. |
| Intervention | The treatment, procedure, or test being studied. |
| Placebo | A substance or treatment with no active medicine, used for comparison to see if the real treatment works. |
| Primary endpoint/outcome | The main result the trial is designed to measure, such as whether a treatment improves symptoms or slows disease. |
| Protocol | The detailed plan for how the trial is conducted, including who can join, what treatments are given, and what is measured. |
| Randomized | Participants are assigned to different treatments by chance, like flipping a coin. |