Definitions of clinical trial terms that you may run across when evaluating clinical trials. If you run across a term you don’t understand and don’t see listed here, please contact us.
Active, not recruiting — The study is ongoing, and participants are receiving an intervention or being examined, but potential participants are not currently being recruited or enrolled.
Adverse Event — An unfavorable change in the health of a participant, including adnormal laboratory findings, that happens during a clinical study or within a certain amount of time after the study has ended. This change may or may not be caused by the intervention/treatment being studied.
Accepts healthy volunteers — A type of eligibility criteria that indicates whether people who do not have the condition/disease being studied can participate in the clinical study.
Active comparator arm — An arm type in which a group of participants receives an intervention/treatment considered to be effective or active by health care providers.
Arm type — A general description for the clinical trial arm. It identifies the role of the intervention that participants receive. Types of arms include the experimental arm, active comparter arm, placedo comparter arm, sham comparter arm, and no intervention arm.
Behavioral Trials — A research study in which one or more human participants are assigned to one or more interventions. In order to evaluate the effects of the intervention on health-related biomedical or behavioral outcomes.
Baseline characteristics — Data collected at the beginning of a clinical study for all participants and for each arm or comparison group. These data demographics such as age, sex/gender, race and ethnicity, and study-specific measures (for example, systolic blood pressure, prior antidepressant treatment).
Clinical Trials — Another name for an interventional study.
Cohort — A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Completed — The study has ended normally, and participants are no longer being examined or treated.
Cross-over assignment — A type of interventional model describing a clinical trial in which groups of participants receive two or more interventions in a specific order. For example two by two cross-over assignment involves two groups of participants. One group receives drug A during the initial phase of the trial, followed by drug B during a later phase. The other group receives drug B during the initial phase followed by drug A. So during the trial, participants “cross over” to the other drug. All participants receive drug And drug B at some point during the trial but in a different order, depending on the group to which they are assigned.
Data-Monitoring Committee (DMC) — A group of independent scientists who monitor the safety and scientific integrity of a clinical trial. The DMC can recommend to the sponsor that the trial be stopped if it is not effective, is harming participants or is unlikely to serve its scientific purpose. Members are chosen based on the scientific skill and knowledge needed to monitor the particular data.
Diagnostic Trials — Diagnostic trials are trials that are conducted to find better tests or procedures for diagnosing a particular disease or condition.
Double-Blind Study — 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.
Early Phase 1 — A phase of research used to describe exploratory trials conducted before traditional phase 1 trial to investigate how or whether a drug affects the body. They involve very limited human exposure to the drug and no therapeutic or diagnostic goals.
Eligibility Criteria — The key requirements that people who want to participate in a clinical must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria and exclusion criteria. Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements or is limited by sex.
End-points — An endpoint is the primary outcome that is being measured by a clinical trial.
Enrolling by invitation — A clinical study that selects its participants from a population or group of people decided on in advance by researchers
Exclusion Criteria — A type of eligibility criteria. These are reasons that a person is not allowed to participate in a clinical study.
Enrollment — The number of participants in a clinical study. The “estimated” enrollment is the target number of participants that the researchers need for the study.
Expanded Access — A way for patients with serious diseases or conditions who cannot participate in a clinical trial to gain access to a medical product that has not been approved by the U.S. Food and Drug Administration. This is also called compassionate use.
Expanded Access Status: Available — Expanded access is currently available for investigational treatment, and patients who are not participants in the clinical study may be able to gain access to the drug, biologic, or medical device being studied.
Expanded Access Status: No Longer Available — Expanded Access was available for intervention previously but is not currently available and will not be available in the future.
Expanded Access Status: Temporarily not Available — Expanded Access is not currently available for this intervention but is extended to be available in the future.
Expanded Access Status: Approved for marketing — The intervention has been approved by the U.S. Food and Drug Administration for use by the public.
Expanded Access Type: Individual Patients — Allows a single patient, with a serious disease or condition who cannot participate in a clinical trial, access to a drug or biological product that has not been approved by the FDA. This category also includes access in an emergency situation.
Expanded Access Type: Intermediate-size Population — Allows more than one patient access to a drug or biological product that has not been approved by the FDA. This type of expanded access is used when multiple patients with the same disease or condition seek access to a specific drug or biological product has not been approved by the FDA.
Expanded Access Type: Treatment IND/ Protocol — Allows a large, widespread population access to a drug or biological product that has not been approved by the FDA. This type of expanded access can only be provided if the product is already developed for marketing for the same use as the expanded access use.
Experimental Arm — The identified role of the intervention that the participant receives that is the focus of the study.
Extension request — In certain circumstances, a sponsor or investigator may request an extension to delay the standard results submission deadline. The request for an extension must demonstrate good cause. All requests must be reviewed and granted by the National Institute of Health. This process for review and granting of extension requests is being developed.
Factorial assignment — A type of intervention model describing a clinical trial in which groups of participants receive one of several combinations of therapies or interventions. For example, a two-by-two factorial assignment would include four participation groups, where all possible combinations of interventions would be observed. (ie. all possible combos would be used: (1) drug A and drug B, (2) drug A and a placeboAn inactive substance or treatment that looks the same as, and is given in the same way as, an active drug or intervention/treatment being studied., (3) a placebo and drug B, or (4) a placebo and a placebo.)
FDA — An agency within the U.S. Department of Health and Human Services. The FDA is responsible for protecting the public health by making sure that human and veterinary drugs, vaccines and other biological products, medical devices, the nation’s food supply, cosmetics, dietary supplements, and products that give off radiation are safe, effective, and secure.
First posted — The date on which the study was first available on ClinicalTrials.gov after the National Library of Medicine quality review was conducted. There is typically a delay of a few days between the date the study sponsor/investigator submits the study record and the date it is posted.
Human subjects protection review board — A group of people who review, approve, and monitor the clinical study’s protocol. Their role is to protect the rights and welfare of people participating in a study such as reviewing the informed consent form. The group typically includes people with varying backgrounds, including a community member, to make sure that research activities conducted by an organization are completely and adequately reviewed.
Inclusion Criteria — A type of eligibility criteria. These are the reasons that a person is allowed to participate in a clinical study.
Informed Consent — A process used by researchers to communicate to potential and enrolled participants the risks and potential benefits of participating in a clinical study.
Interventional model — The general design of the strategy for assigning intervention to participate in a clinical study. Types of intervention models include: single group assignment, parallel assignment, cross over the assignment, and factorial assignment.
Interventional study (clinical trial) — A type of clinical study in which participants are assigned to groups that receive one or more interventions/treatments so that researchers can evaluate the effects of the intervention on biomedical or health-related outcomes. The assignments are determined by the study’s protocol. Participants may receive diagnostic, therapeutic, or other types of interventions.
Investigator — A researcher involved in a clinical study.
IRB — Institutional Review Board- an independent ethics committee for the methods of research.
Masking — A clinical trial design strategy in which one or more parties involved in the trial, such as the investigator or participants, do not know which participants were assigned which interventions. Types of masking include single-blind masking and double-blind masking.
NIH — National Institute of Health
Not yet recruiting — The study has not started recruiting participants.
Observational Trials — Studies geared to find what happens to people in different situations based on people observing others.
Outcome Measure — The result of a treatment or intervention that is used to objectively determine the baseline function of a patient at the beginning of the clinical trial.
Parallel Assignment — A interventional model in which two or more groups of participants receive different interventions.
Patient Registry — A type of observational study that collects information about patients’ medical conditions and/or treatments to better understand how a condition or treatment affects patients in the real world.
Phase 1 — A phase of research to describe clinical trials that focuses on the safety of a drug. The goal is to determine the drug’s most frequent and serious adverse effects and, often, how the drug is broken down and excreted by the body. These trials usually involve a small number of participants.
Phase 2 — A phase of research to describe clinical trials that gather preliminary data on whether a drug works in people who have a certain condition/disease.
Phase 3 — A phase of research to describe clinical trials that gather more information about a drug’s safety and effectiveness by studying different populations and different dosages and by using the drug in combination with other drugs. These studies typically involve more participants.
Phase 4 — A phase of research to describe clinical trials occurring after FDA has approved a drug for marketing. They include postmarketing requirements and commitment studies that are required of or agreed to by the study sponsor. These trials gather additional information about a drug’s safety, efficacy, or optimal use.
Placebo — An inactive substance or treatment that looks the same as, and is given in the same way as, an active drug or intervention/treatment being studied.
Placebo-controlled — Some patients exclusively receive the study drug or treatment and some patients exclusively receive a placebo.
Placebo crossover — Study includes a point whereby participants change study arms, although the timing of that change and whether drug or placebo is received remains blind to all. Some may take placebo for 4 weeks, have a 2-week wash-out with no drug or placebo, and then switch to taking the study for 4 weeks, for example. Others in the same study would begin with study drug for 4 weeks, 2-week wash-out and then cross over to take the placebo for 4 weeks.
Prevention Trials — FInding ways to prevent particular medical conditions or if people have them already, to prevent them from reoccurring.
Principal Investigator — The person who is responsible for the scientific and technical direction of the entire clinical study.
Protocol — Documents that describe the objectives, design, methodology, statistical considerations, and aspects related to the organization of clinical trials.
Quality Control — Procedures which ensure protection of human subjects from research risk, reliability of the data, and thereby assure internal consistency.
Quality of life trials — Clinical trials that involve the best way to improve quality of life conditions for patients with a chronic illness.
Randomized — The arm of the study (active treatment arm or placebo arm) that the patient will follow is determined by a flip of a coin (or like randomizing procedure).
Randomized Allocation — A type of allocation strategy in which participants are assigned to the groups of participants of a clinical trial by chance.
Recruiting — Patient recruitment includes a variety of services typically performed by a Patient Recruitment Service Provider to increase enrollment into clinical trials.
Recruitment Status — In a clinical trial, the current status for participants indicates what stage the trial is in.
Reporting group — A grouping of participants in a clinical study that is used for summarizing the data collected during the study. This grouping may be the same as or different from a study arm or group.
Results database — A structured online system that provides the public with access to registration and summary results information for completed or terminated clinical studies. The ClinicalTrials.gov results database became available in September 2008. Older studies are unlikely to have results available in the database.
Safeguards and Ombudsmen — Many checks and balances are in place to ensure safety.
Screening Trials — The process to determine if you qualify for the trial.
Sham Comparter arm — An arm type in which a group of participants receives a procedure or device that appears to be the same as the actual procedure or device being studied but does not contain active processes or components.
Single group assignment — A type of intervention model describing a clinical trial in which all of the participants receive the same intervention/treatment.
Sponsor — A person, company, institution, group, or organization that oversees or pays for a clinical trial and collects and analyses the data.
Suspended — The study has stopped early but may start again.
Study registry — A structured online system, such as ClinicalTrials.gov , that provides the public with access to summary information about ongoing and completed clinical studies.
Study record — An entry on Clinicaltrials.gov that contains a summary of a clinical study’s protocol information, including the recruitment status; eligibility criteria; contact information; and in some cases, summary results.
Study results — A study record that includes the summary results posted in the ClinicalTrials.gov results database. Summary results information includes participant flow, baseline characteristics, outcome measures, and adverse events (including serious adverse events).
Terminated — The study has stopped early and will not start again.
Treatment Trials — Clinical trials advance through four phases to test a treatment, find the appropriate dosage, and look for side effects. If after the first three phases, researchers find a drug or other intervention to be safe and effective, the FDA approves it for clinical use and continues to monitor its effects.
Unknown — A study on Clinicaltrials.gov whose last known status was recruiting; not yet recruiting; or active, not recruiting but that has passed its completion date, and the status has not been last verified within the past 2 years.
Withdrawn — The study stopped early, before enrolling its first participants.
