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Advanced Search Field Definitions

The following search fields are available on the Advanced Search page. They are listed in the order in which they appear on the form. To view information on a search field, click on its name below. You can also click on the field label on the Advanced Search form to access information for that field.


Study Type—Use this field to limit your search to one of the following clinical study types:

  • All Studies
  • Interventional Studies (or Clinical Trials): Clinical studies in which participants are assigned to receive one or more interventions (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 protocol. Participants may receive diagnostic, therapeutic, or other types of interventions.
  • Observational Studies: Clinical studies in which participants identified as belonging to study groups 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 specific interventions (as in an interventional study).
    • Patient Registries: A type of Observational Study that collects uniform data prospectively for a population defined by a particular disorder/disease, condition, or exposure and that serves a predetermined scientific, clinical, or policy purpose.
  • Expanded Access: A process regulated by the Food and Drug Administration (FDA) that allows manufacturers to provide investigational new drugs to patients with serious diseases or conditions who cannot participate in a clinical trial. For more information on expanded access, visit the Expanded Access: Information for Patient page on the FDA Web site.

Study Results—Use this field to search based on whether a study has results posted in the ClinicalTrials.gov results database. You can select one of the following search options:

  • All Studies
  • Studies With Results
  • Studies Without Results
The ClinicalTrials.gov results database provides the public with access to summary results and registration information for completed or terminated clinical studies. Further, study results are often published in medical journals. On ClinicalTrials.gov, publication citations are displayed at the bottom of the Full Text View and Study Results tabs as well as the No Study Results Posted tab of a study record, under the More Information heading. See the How to Find Results of Studies page to learn more.

Note: The ClinicalTrials.gov results database became available in September 2008. Older studies are unlikely to have results in the database.

Status—Use this field to specify whether you want to search for studies that are recruiting participants or in other stages.

  • Studies: To search by status of an interventional study (clinical trial) or an observational study use the options listed. Studies that are recruiting participants or not yet recruiting participants appear in green text in ClinicalTrials.gov search results and study records. Statuses that are no longer accepting participants, are completed, or are stopped for some other reason appear in red text. The statuses are:

    Not yet recruiting
    Recruiting
    Enrolling by invitation
    Active, not recruiting
    Suspended
    Terminated
    Completed
    Withdrawn

    Note: Studies marked as "Unknown" in brown text have a Recruiting, Not yet recruiting, or Active, not recruiting status that has not been verified on ClinicalTrials.gov by the sponsor of the study or responsible party within the past 2 years.

  • Expanded Access: Use these options to search for information on investigational drugs that are or were available to patients who cannot participate in a clinical trial. If an investigational drug may be available for expanded access, the status will appear in green text in ClinicalTrials.gov search results and study records. If access is no longer available, statuses appear in red text. The statuses are:

    Available for expanded access
    No longer available for expanded access
    Temporarily not available for expanded access
    Approved for marketing

See Recruitment Status in the glossary for the definitions of each status.

Age or Age Group—Use these fields to limit your search to studies that accept participants with the specified age or from the selected age groups. You may either enter a specific age, in years, in the Age field or you may click on the check box to the left of each age group you wish to include in your search. More than one age group may be selected.

Partial years may be entered using a decimal value. For example, 23 and 1/2 years would be entered as 23.5

If you enter a specific age in the Age field and select one or more age groups then studies covering either that age or the age group will be included.

If you do not specify an age or select any age group, then all ages will be included.

The age groups are:

  • Child (birth–17)
  • Adult (18–65)
  • Senior (66+)

Sex—Use this field to search by the sex of persons who may participate in a study. You can select one of the following search options

  • All (Studies with Male and Female Participants)
  • Studies With Female Participants
  • Studies With Male Participants

Accepts Healthy Volunteers—Use this checkbox to limit your search to studies which accept healthy participants (people who do not have the condition or related conditions or symptoms being studies).

Condition/Disease—Use this field to specify 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.

Intervention/Treatment—Use this field to specify a process or action that is the focus of a clinical study. This can include giving participants drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches such as surveys, education, and interviews.

Examples: clofibrate, cyclosporine, vitamin E, pacemaker, PET scan

Title Acronym/Titles—Use this field to specify the study title acronym or an exact phrase from the brief or official title of the study you want to find.

Example: WHI

Outcome Measures—Use this field to specify a measurement, decided on in advance, that is used to determine the effect of interventions on participants in a clinical trial. For observational studies, specify 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 primary outcome measure and secondary outcome measure .

Examples: weight loss, ejection fraction, muscle strength

Sponsor/Collaborators—Use this field to specify the Sponsor (Lead) or Collaborator listed on study records. A sponsor is the organization or person (a Sponsor-Investigator) who oversees the clinical study and is responsible for analyzing the study data. A collaborator is an organization other than the Sponsor that provides support for a clinical study. This support may include funding, design, implementation, data analysis, or reporting.

  • Examples: National Cancer Institute, Mayo Clinic, Bristol-Myers Squibb
  • Exact match: Use this checkbox to indicate that the sponsor name listed in the study must exactly match the sponsor name entered in the search field. For example, if this checkbox is not marked, a search with "Merck" in the Sponsor (Lead) field will find studies with Merck, Merck KGaA, Dupont Merck, and Merck Sharp & Dohme listed as the sponsor. If the checkbox is marked, only studies with Merck listed as the sponsor (with no other words in the name) will be included in the search results.

  • Examples: National Cancer Institute, Mayo Clinic, Bristol-Myers Squibb
  • Exact match: Use this checkbox to indicate that the sponsor name listed in the study must exactly match the sponsor name entered in the search field. For example, if this checkbox is not marked, a search with "Merck" in the Sponsor (Lead) field will find studies with Merck, Merck KGaA, Dupont Merck, and Merck Sharp & Dohme listed as the sponsor. If the checkbox is marked, only studies with Merck listed as the sponsor (with no other words in the name) will be included in the search results.

Study IDs—Use this field to search for a clinical study by an identification number.

Every clinical study is associated with identification numbers assigned to the clinical study protocol by the sponsor, funders, or others. These include unique identifiers from other registries and National Institutes of Health grant numbers. In addition, ClinicalTrials.gov assigns a ClinicalTrials.gov Identifier, or NCT Number, a unique identification code given to each clinical study registered on ClinicalTrials.gov. The format is "NCT" followed by an 8-digit number (for example, NCT00000419). This identifier is also known as the NCT Number.

Country/State—Studies are often conducted in many locations around the world. Use this field to select up to three locations to search for studies. For the United States, you can narrow your search by selecting a state.

Location Terms—If you are interested in a specific city (such as Los Angeles) or facility (such as the Mayo Clinic), enter it in the Location Terms field.

Note: Not all studies include this level of detail.

Phase—Use this field to select the study phase you want to include in your search. You can select more than one study phase. If you do not select any study phase, all study phases, including Early Phase, will be included in your search results.

Phases are Food and Drug Administration (FDA) categories for describing the study of a drug based on the study's characteristics, such as the objective and number of participants. The phases include:
  • Early Phase 1 (formerly listed as Phase 0): Exploratory study involving very limited human exposure to the drug, with no therapeutic or diagnostic goals (for example, screening studies, microdose studies)
  • Phase 1: Studies that are usually conducted with healthy volunteers and that emphasize safety. The goal is to find out what the drug's most frequent adverse events are and, often, how the drug is metabolized and excreted.
  • Phase 2: Studies that gather preliminary data on effectiveness (whether the drug works in people who have a certain disease or condition). For example, participants receiving the drug may be compared with similar participants receiving a different treatment, usually an inactive substance (called a placebo) or a different drug. Safety continues to be evaluated, and short-term adverse events are studied.
  • Phase 3: Studies that gather more information about safety and effectiveness by studying different populations and different dosages and by using the drug in combination with other drugs
  • Phase 4: Studies occurring after FDA has approved a drug for marketing. These include postmarket requirement and commitment studies that are required of or agreed to by the sponsor. These studies gather additional information about a drug's safety, efficacy, or optimal use.
See Learn About Studies to learn more about the phases of drug trials.

Funder Type—Use this field to select the funder type you want to include in your search. You can select more than one funder type. If you do not select any funder type, all funder types will be included in your search results.

Funder type describes the organization that provides funding or support for the study. Support may include providing facilities, expertise, or financial resources. Organizations listed as sponsors and collaborators for a study are considered the funders of the study. There are four types of funders:
  • National Institutes of Health (NIH)
  • Other U.S. Federal agency: For example, the Food and Drug Administration, Centers for Disease Control and Prevention, U.S. Department of Veterans Affairs
  • Industry: Pharmaceutical and device companies
  • All others (individuals, universities, organizations)

First Posted—Specify a From date to find studies available on ClinicalTrials.gov on or after that date. Specify a To date to find studies available on or before that date. Specify both From and To dates to find studies that were available on ClinicalTrials.gov during a certain time period. If no dates are entered, all studies will be included in your search results.

Dates should be entered in MM/DD/YYYY format. For example, March 1, 2010, is entered as "03/01/2010."
The First Posted date is the date on which the study record was first available on ClinicalTrials.gov. There is typically a delay of a few days between when the study record was submitted to ClinicalTrials.gov by the study sponsor or investigator (First Submitted date) and the First Posted date.

Last Update Posted—Specify a From date to find studies with updates available on ClinicalTrials.gov on or after that date. Specify a To date to find studies with updates available on or before that date. Specify both From and To dates to find studies with updates available during a certain time period. If no dates are entered, all studies will be included in your search results.

Dates should be entered in MM/DD/YYYY format. For example, March 1, 2010, is entered as "03/01/2010."
The Last Update Posted date is the most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when changes were submitted to ClinicalTrials.gov by the study sponsor or investigator (last update submitted date) and the Last Update Posted date.

This page last reviewed in September 2017