A type of that indicates whether people who do not have the being studied can participate in that clinical study.

An in which a group of participants receives an considered to be effective (or active) by health care providers.

An unfavorable change in the health of a participant, including abnormal 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 being studied.

A type of that indicates the age a person must be to participate in a clinical study. This may be indicated by a specific age or the following age groups:

A measure of all deaths, due to any cause, that occur during a clinical study.

A method used to assign participants to an arm of a clinical study. The types of allocation are and nonrandomized.

A group or subgroup of participants in a clinical trial that receives a specific , or no intervention, according to the trial's .

A general description of the clinical trial arm. It identifies the role of the intervention that participants receive. Types of arms include , , , , and .

Data collected at the beginning of a clinical study for all participants and for each arm or comparison group. These data include demographics, such as age, sex/gender, race and ethnicity, and study-specific measures (for example, systolic blood pressure, prior antidepressant treatment).

Indicates that the study sponsor or investigator recalled a submission of before took place. If the submission was canceled on or after May 8, 2018, the date is shown. After submission of study results, a cannot be modified until QC review is completed, unless the submission is canceled.

Information required by the . In general, this is a description of any agreement between the sponsor of a clinical study and the (PI) that does not allow the PI to discuss the results of the study or publish the study results in a scientific or academic journal after the study is completed.

A sponsor or investigator may submit a certification to delay submission of results information if they are applying for FDA approval of a new drug or device, or new use of an already approved drug or device. A sponsor or investigator who submits a certification can delay results submission up to 2 years after the date, unless certain events occur sooner. See in the Results Data Element definitions for more information about this certification.

The date on which information about a to delay submission of results or an was first available on ClinicalTrials.gov. ClinicalTrials.gov does not indicate whether the submission was a certification or extension request. There is typically a delay between the date the study sponsor or investigator submitted the certification or extension request and the .

The date on which the study sponsor or investigator first submitted a or an to delay submission of results. A sponsor or investigator who submits a certification can delay results submission up to 2 years after this date, unless certain events occur sooner. There is typically a delay between the date the certification or extension request was submitted and the date the information is first available on ClinicalTrials.gov ().

The date on which the study sponsor or investigator first submitted a or an that is consistent with National Library of Medicine (NLM) criteria. The sponsor or investigator may need to revise and submit a certification or extension request one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria. Meeting QC criteria for an extension request does not mean that the National Institutes of Health (NIH) has determined that the request demonstrates good cause. The process for review and granting of extension requests by the NIH is being developed.

In the search feature, the City field is used to find clinical studies with locations in a specific city. The Distance field is used to find studies with locations within the specified distance from a city in number of miles. For example, if you choose Illinois as the , identifying "Chicago" as the city and "100 miles" as the distance will find all studies listing a location within 100 miles of Chicago.

A research study involving human volunteers (also called participants) that is intended to add to medical knowledge. There are two types of clinical studies: (also called clinical trials) and .

Another name for an .

The unique identification code given to each clinical study upon at ClinicalTrials.gov. The format is "NCT" followed by an 8-digit number (for example, NCT00000419).

An organization other than the that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

In the search feature, the Country field is used to find clinical studies with locations in a specific country. For example, if you choose the United States, you can then narrow your search by selecting a and identifying a .

A type of 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 A and drug B at some point during the trial but in a different order, depending on the group to which they are assigned.

A group of independent scientists who monitor the safety and scientific integrity of a . 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 skills and knowledge needed to monitor the particular trial. Also called a data safety and monitoring board, or DSMB.

A of research used to describe exploratory trials conducted before traditional trials to investigate how or whether a drug affects the body. They involve very limited human exposure to the drug and have no therapeutic or diagnostic goals (for example, screening studies, microdose studies).

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both (which are required for a person to participate in the study) and (which prevent a person from participating). Types of eligibility criteria include whether a study , has requirements, or is limited by .

The number of participants in a clinical study. The "estimated" enrollment is the target number of participants that the researchers need for the study.

A type of . These are reasons that a person is not allowed to participate in a clinical study.

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 . Also called compassionate use. There are different .

Describes the category of under regulations. There are three types of expanded access:

An in which a group of participants receives the that is the focus of the clinical trial.

In certain circumstances, a sponsor or investigator may request an extension to delay the standard results submission deadline (generally one year after the ). The request for an extension must demonstrate good cause (for example, the need to preserve the scientific integrity of an ongoing trial). All requests must be reviewed and granted by the National Institutes of Health. This process for review and granting of extension requests is being developed. See in the Results Data Element definitions for more information.

A type of describing a clinical trial in which groups of participants receive one of several combinations of interventions. For example, two-by-two factorial assignment involves four groups of participants. Each group receives one of the following pairs of interventions: (1) drug A and drug B, (2) drug A and a placebo, (3) a placebo and drug B, or (4) a placebo and a placebo. So during the trial, all possible combinations of the two drugs (A and B) and the placebos are given to different groups of participants.

A FDAAA 801 Violation is shown on a study record when the U.S. Food and Drug Administration (FDA) has issued a Notice of Noncompliance to the responsible party of an applicable clinical trial. A Notice of Noncompliance indicates that the FDA has determined the responsible party was not in compliance with the registration or results reporting requirements for the clinical trial under the Food and Drug Administration Amendments Act of 2007, Section 801 (FDAAA 801).

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).

The date on which the study sponsor or investigator first submits a that is consistent with National Library of Medicine (NLM) criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.

U.S. Public Law 110-85, which was enacted on September 27, 2007. Section 801 of FDAAA amends Section 402 of the U.S. Public Health Service Act to expand ClinicalTrials.gov and create a clinical study . For more information on FDAAA 801, see the page on this site.

Describes the organization that provides funding or support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting. Organizations listed as and for a study are considered the funders of the study. ClinicalTrials.gov refers to four types of funders:

A type of that indicates whether eligibility to participate in a clinical study is based a person's self-representation of gender identity or gender (yes, no). Gender is distinct from .

A group or subgroup of participants in an that is assessed for biomedical or health outcomes.

A group of people who review, approve, and monitor the clinical study's . Their role is to protect the rights and welfare of people participating in a study (referred to as human research subjects), such as reviewing the . 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. Also called an institutional review board, or IRB, or an ethics committee.

A type of . These are the reasons that a person is allowed to participate in a clinical study.

A process used by researchers to communicate to potential and enrolled participants the risks and potential benefits of participating in a clinical study.

The document used in the or process.

The general design of the strategy for assigning interventions to participants in a clinical study. Types of intervention models include: , , , and .

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

A type of in which participants are assigned to groups that receive one or more (or no intervention) so that researchers can evaluate the effects of the interventions on biomedical or health-related outcomes. The assignments are determined by the study's . Participants may receive diagnostic, therapeutic, or other types of interventions.

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study .

The most recent date on which changes to a were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the date) and the last update posted date.

The most recent date on which the study sponsor or investigator submitted changes to a to ClinicalTrials.gov. There is typically a delay of a few days between the last update submitted date and when the date changes are posted on ClinicalTrials.gov (the date).

The most recent date on which the study sponsor or investigator submitted changes to a that are consistent with National Library of Medicine (NLM) criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's is shown as .

Countries in which research facilities for a study are located. A country is listed only once, even if there is more than one facility in the country. The list includes all countries as of the date; any country for which all facilities were removed from the are listed under .

In the search feature, the Location terms field is used to narrow a search by location-related terms other than Country, State, and City or distance. For example, you may enter a specific facility name (such as National Institutes of Health Clinical Center) or a part of a facility name (such as Veteran for studies listing Veterans Hospital or Veteran Affairs in the facility name). Note: Not all include this level of detail about locations.

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 have been assigned which interventions. Types of masking include: open label, single blind masking, and double-blind masking.

A unique identification code given to each clinical study record registered on ClinicalTrials.gov. The format is "NCT" followed by an 8-digit number (for example, NCT00000419). Also called the .

An in which a group of participants does not receive any during the clinical trial.

A type of in which participants are identified as belonging to study groups and are assessed for biomedical or health outcomes. Participants may receive diagnostic, therapeutic, or other types of interventions, but the investigator does not assign participants to a specific .

The general design of the strategy for identifying and following up with participants during an . Types of observational study models include cohort, case-control, case-only, case-cross-over, ecologic or community studies, family-based, and other.

An that is not a , meaning that it does not result in death, is not life-threatening, does not require inpatient hospitalization or extend a current hospital stay, does not result in an ongoing or significant incapacity or interfere substantially with normal life functions, and does not cause a congenital anomaly or birth defect; it also does not put the participant in danger and does not require medical or surgical intervention to prevent one of the results listed above.

Identifiers or ID numbers other than the that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.

In the search feature, the Other terms field is used to narrow a search. For example, you may enter the name of a drug or the NCT number of a clinical study to limit the search to that contain these words.

For , a planned measurement described in the protocol that is used to determine the effect of an on participants. For , a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include and .

A type of describing a clinical trial in which two or more groups of participants receive different interventions. For example, a two-arm parallel assignment involves two groups of participants. One group receives drug A, and the other group receives drug B. So during the trial, participants in one group receive drug A "in parallel" to participants in the other group, who receive drug B.

A summary of the progress of participants through each stage of a clinical study, by study or . This includes the number of participants who started, completed, and dropped out of the study.

A type of that collects information about patients' medical conditions and/or treatments to better understand how a condition or treatment affects patients in the real world.

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the . The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: , , , , and . is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.

A of research to describe clinical trials that focus on the safety of a drug. They are usually conducted with healthy volunteers, and the goal is to determine the drug's most frequent and and, often, how the drug is broken down and excreted by the body. These trials usually involve a small number of participants.

A of research to describe clinical trials that gather preliminary data on whether a drug works in people who have a certain (that is, the drug's effectiveness). For example, participants receiving the drug may be compared to similar participants receiving a different treatment, usually an inactive substance (called a ) or a different drug. Safety continues to be evaluated, and short-term are studied.

A 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.

A of research to describe clinical trials occurring after FDA has approved a drug for marketing. They include postmarket requirement 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.

Describes trials without FDA-defined , including trials of devices or behavioral interventions.

An inactive substance or treatment that looks the same as, and is given in the same way as, an active drug or being studied.

An in which a group of participants receives a during a clinical trial.

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the . Whether the clinical study ended according to the or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "estimated" primary completion date is the date that the researchers think will be the primary completion date for the study.

In a clinical study's , the planned outcome measure that is the most important for evaluating the effect of an . Most clinical studies have one primary outcome measure, but some have more than one.

The main reason for the . The types of primary purpose are: treatment, prevention, diagnostic, supportive care, screening, health services research, basic science, and other.

The person who is responsible for the scientific and technical direction of the entire clinical study.

The written description of a clinical study. It includes the study's objectives, design, and methods. It may also include relevant scientific background and statistical information.

National Library of Medicine (NLM) staff perform a limited review of submitted for apparent errors, deficiencies, or inconsistencies. NLM staff identify potential major and advisory issues and provide comments directly to the study sponsor or investigator. Major issues identified in QC review must be addressed or corrected (see and ). Advisory issues are suggestions to help improve the clarity of the record. NLM staff do not verify the scientific validity or relevance of the submitted information. The study sponsor or investigator is responsible for ensuring that the studies follow all applicable laws and regulations.

A type of strategy in which participants are assigned to the of a clinical trial by chance.

The process of submitting and updating summary information about a clinical study and its , from its beginning to end, to a structured, public Web-based that is accessible to the public, such as ClinicalTrials.gov.

Countries that appeared under but were removed from the by the sponsor or investigator.

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.

The person responsible for submitting information about a clinical study to ClinicalTrials.gov and updating that information. Usually the study sponsor or investigator.

A structured online system, such as the ClinicalTrials.gov results database, that provides the public with access to registration and summary results information for completed or terminated clinical studies. A study with results available on ClinicalTrials.gov is described as having the results "posted."

Indicates that the sponsor or investigator submitted a or .

The date on which summary results information was first available on ClinicalTrials.gov after National Library of Medicine (NLM) has concluded. There is typically a delay between the date the study sponsor or investigator first submits summary results information (the results first submitted date) and the results first posted date. Some results information may be available at an earlier date if .

The date on which summary results information was first available on ClinicalTrials.gov with quality control review comments from the National Library of Medicine (NLM) identifying major issues that must be addressed by the sponsor or investigator. As of January 1, 2020, initial results submissions for applicable clinical trials (ACTs) that do not meet will be publicly posted on ClinicalTrials.gov with brief standardized major comments. Accordingly, the Results First Posted with QC Comments date may be earlier than the Results First Posted date for an ACT with summary results information that is not consistent with NLM quality control review criteria.

The date on which the study sponsor or investigator first submits a with summary results information. There is typically a delay between the results first submitted date and when summary results information becomes available on ClinicalTrials.gov (the date).

The date on which the study sponsor or investigator first submits a with summary results information that is consistent with National Library of Medicine (NLM) criteria. The sponsor or investigator may need to revise and submit results information one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.

The date on which the National Library of Medicine provided comments to the study sponsor or investigator. The sponsor or investigator must address major issues identified in the review comments. If there is a date listed for results returned after quality control review, but there is not a subsequent date listed for , this means that the submission is pending changes by the sponsor or investigator.

Indicates that the study sponsor or investigator has submitted summary results information for a clinical study to ClinicalTrials.gov but the process has not concluded.

In a clinical study's , a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.

An that results in death, is life-threatening, requires inpatient hospitalization or extends a current hospital stay, results in an ongoing or significant incapacity or interferes substantially with normal life functions, or causes a congenital anomaly or birth defect. Medical events that do not result in death, are not life-threatening, or do not require hospitalization may be considered serious adverse events if they put the participant in danger or require medical or surgical intervention to prevent one of the results listed above.

A type of that indicates the sex of people who may participate in a clinical study (all, female, male). Sex is a person's classification as female or male based on biological distinctions. Sex is distinct from .

An 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.

A type of describing a clinical trial in which all participants receive the same intervention/treatment.

In Advanced Search, the Sort studies by option is used to change the order of studies listed on the Search Results page. You can sort by Relevance or Newest First:

The organization or person who initiates the study and who has authority and control over the study.

In the search feature, the State field is used to find clinical studies with locations in a specific state within the United States. If you choose United States in the field, you can search for studies with locations in a specific state.

The written description of the statistical considerations and methods for analyzing the data collected in the .

Indicates the current or the .

The date on which the last participant in a clinical study was examined or received an to collect final data for the , , and (that is, the last participant's last visit). The "estimated" study completion date is the date that the researchers think will be the study completion date.

The investigative methods and strategies used in the clinical study.

Refers to the type of documents that the study sponsor or principal investigator may add to their . These include a study , , and .

Identifiers that are assigned to a clinical study by the study's , funders, or others. They include unique identifiers from other trial and National Institutes of Health grant numbers. Note: ClinicalTrials.gov assigns a unique identification code to each clinical study registered on ClinicalTrials.gov. Also called the , the format is "NCT" followed by an 8-digit number (for example, NCT00000419).

An entry on ClinicalTrials.gov that contains a summary of a clinical study's protocol information, including the ; eligibility criteria; contact information; and, in some cases, summary results. Each study record is assigned a ClinicalTrials.gov identifier, or .

A structured online system, such as ClinicalTrials.gov, that provides the public with access to summary information about ongoing and completed clinical studies.

A that includes the summary results posted in the ClinicalTrials.gov . Summary results information includes , , , and (including ).

The actual date on which the first participant was enrolled in a clinical study. The "estimated" study start date is the date that the researchers think will be the study start date.

Describes the nature of a . Study types include (also called clinical trials), (including ), and .

The date on which the study sponsor or investigator submitted a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria.

The official title of a used to identify a clinical study or a short title written in language intended for the lay public.

The acronym or initials used to identify a clinical study (not all studies have one). For example, the title acronym for the Women's Health Initiative is "WHI."

An agency within the U.S. Department of Health and Human Services. AHRQ's mission is to produce evidence to make health care safer, higher quality, more accessible, equitable, and affordable, and to work within the U.S. Department of Health and Human Services and with other partners to make sure that the evidence is understood and used.

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.

A type of . It identifies 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 verified within the past 2 years. Studies with an unknown status are considered closed studies.