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AACT Data Dictionary

AACT is composed of 40 tables that provide information related to clinical trials. Every table is related by NCT ID to the Studies table. Click here to view a listing of all 40 tables with description and row counts. Detailed information about all data elements included in these tables can be found in the data dictionary below.

AACT documentation may be downloaded from the following links:

Please refer to the National Library of Medicine's (NLM) documentation for authoritative definitions of the data elements:

AACT Data Elements

The Data Dictionary (table below) provides detailed information about each data element in the AACT database. Every study-related table/column in the AACT relational database is represented as a row in this table. (AACT includes a few administrative tables that contain data not directly related to studies. Information about these tables is not included in the data dictionary. Information about these tables is available.)

Click on the icon that appears at the beginning of the data element row to view the section of the NLM documentation that defines that particular data element. (The icon appears only for data element defined by NLM.)

  • Sort: Click on a column header to sort the table alphabetically by the values in that column.

  • Search/Filter: An input box appears under each column name. Enter a search term in one or more boxes & press [Enter] to filter the display. You many enter values in multiple columns to further restrict a search. The filter ignores case and will find all data elements that 'include' the term you enter (ie. your term does not need to be the complete value.)

  • Search Support: The first column provides icons that support filtering. The larger magnifying glass in the top row toggles display of the filter row. The smaller magnifying glass below it can be clicked to launch a search (same as pressing [Enter]). Clicking the funnel icon will clear filter values.

  • Authoritative Source: Please refer to the National Library of Medicine's (NLM) documentation for official definitions of all study/protocol and results data data elements. The icon that appears at the beginning of a row will open a tab in your browser to display NLM information about the data element on that row.

  • Horizontal Scroll: All columns do not fit on a page; you may scroll horizontally to view and filter on additional information about the data elements.

  • Source Column This column identifies the XML tag path used to obtain values for the data element from ClinicalTrials.gov API. Click here for the XML format specifications (xsd) and here to see an example of a study as provided by NLM via their API; this represents the source information used to populate the AACT database.

  • Row Count Column Each table's primary key definition includes the table's current row count.

  • Enumerations Column Some AACT table columns are used to store a discrete set of predefined terms (enumerations). For example, Study.enrollment_type can only contain values: 'Anticipated', 'Actual' or null. If the table/column is for a set of enumerations, the data dictionary presents each of the enumeration values along with the corresponding number of rows with that value.

AACT Tables

The list below describes the 40 study-related tables in the AACT database and provides current row counts for each.

name row count description db section rows per study
Baseline_Counts 80,647 Sample size at baseline for each study group; usually a count of participants but can represent other units of measure such as 'hands', 'hips', etc. Results many
Baseline_Measurements 703,507 Summaries of demographic & baseline measures collected by arm or comparison group and for the entire population of participants in the clinical study.  Results many
Brief_Summaries 258,723 A single text column that provides a brief description of the study. Protocol one
Browse_Conditions 459,927 NLM uses an internal algorithm to assess the data entered for a study and creates a list of standard MeSH terms that describe the condition(s) being addressed by the clinical trial. This table provides the results of NLM's assessment Protocol many
Browse_Interventions 276,642 NLM uses an internal algorithm to assess the data entered for a study and creates a list of standard MeSH terms that describe the intervention(s) being addressed by the clinical trial. This table provides the results of NLM's assessment Protocol many
Calculated_Values 259,453 An AACT-provided table that contains info that's been calculated from the information received from ClinicalTrials.gov. For example, number_of_facilities and actual_duration are provided in this table. Protocol one
Central_Contacts 99,423 Contact info for people (primary & backup) who can answer questions concerning enrollment at any location of the study. Protocol many
Conditions 419,465 Name(s) of the disease(s) or condition(s) studied in the clinical study, or the focus of the clinical study. Can include NLM's Medical Subject Heading (MeSH)-controlled vocabulary terms. Protocol many
Countries 380,918 Countries in which the study has facilities/sites. Protocol many
Design_Group_Interventions 548,141 A cross reference for groups/interventions. If a study has multiple groups and multiple interventions, this table shows which interventions are associated with which groups. Protocol many
Design_Groups 443,205 Defines the protocol-specified group, subgroup, or cohort of participants in a clinical trial assigned to receive specific intervention(s) or observations according to a protocol. Protocol many
Design_Outcomes 1,233,502 Description of planned outcome measures and observations that will describe patterns of diseases and traits/associations with exposures, risk factors or treatment. Protocol many
Designs 259,453 Description of how the study will be conducted, including comparison group design and strategies for masking and allocating participants. Protocol one
Detailed_Descriptions 165,443 A single text column that provides a detailed description of the study protocol. Protocol one
Drop_Withdrawals 216,213 Summarized information about how many participants withdrew from the study, when and why. This information explains disposition of participants relative to the numbers starting and completing the study (enumerated in the Milestones table). Results many
Eligibilities 259,453 Information about the criteria used to select participants; includes inclusion and exclusion criteria Protocol one
Facilities 1,901,855 Name, address and recruiting status of the facilities participating in the study. Protocol many
Facility_Contacts 225,871 Contact information for people responsible for the study at each facility. (primary and backup) Facility contact information is available if the facility status (Facilities.Status) is ‘Recruiting’ or ‘Not yet recruiting’, and if the data provider has provided such information. Contact information is removed from the publicly available content at ClinicalTrials.gov when the facility is no longer recruiting, or when the overall study status (Studies.Overall_status) changes to indicate that the study has completed recruitment. Protocol many
Facility_Investigators 170,552 Names of the investigators at each study facility. Facility investigator information is available if the facility status (Facilities.Status) is ‘Recruiting’ or ‘Not yet recruiting’, and if the data provider has provided such information. Investigator information is removed from the publicly available content at ClinicalTrials.gov when the facility is no longer recruiting, or when the overall study status (Studies.Overall_status) changes to indicate that the study has completed recruitment. Protocol many
Id_Information 363,924 Identifiers (other than the NCT ID) that uniquely identify the study such as that assigned by the sponsor, or an NCT ID that had previously been used for the study. Protocol many
Intervention_Other_Names 223,683 Terns or phrases that are synonymous with an intervention. (Each row is linked to one of the interventions associated with the study.) Protocol many
Interventions 451,620 The interventions or exposures (including drugs, medical devices, procedures, vaccines, and other products) of interest to the study, or associated with study arms/groups. Protocol many
Keywords 763,579 Provides words or phrases that best describe the protocol. Keywords help users find studies in the database. Can include NLM's Medical Subject Heading (MeSH)-controlled vocabulary terms. Protocol many
Links 48,300 Web site directly relevant to the protocol. (ie, links to educational, research, government, and other non-profit Web pages) Protocol many
Milestones 285,330 Information summarizing the progress of participants through each stage of a study, including the number of participants who started and completed the trial. Enumeration of participants not completing the study is included in the Drop_Withdrawals table. Results many
Outcome_Analyses 119,471 Results of scientifically appropriate statistical analyses performed on primary and secondary study outcomes. Includes results for treatment effect estimates, confidence intervals and othe rmeasures of dispersion, and p-values. Results many
Outcome_Analysis_Groups 229,811 Identifies the comparison groups that were involved with each outcome analysis Results many
Outcome_Counts 488,216 Sample size included in analysis for each outcome for each study group; usually participants but can represent other units of measure such as eyes 'lesions', etc. Results many
Outcome_Measurements 1,470,364 Summary data for primary and secondary outcome measures for each study group. Includes parameter estimates and measures of dispersion/precision. Results many
Outcomes 211,674 Descriptions of outcomes, or observation that were measured to determine patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Includes information such as time frame, population and units. (Specific measurement results are stored in the Outcome_Measurements table.) Results many
Overall_Officials 275,050 People responsible for the overall scientific leadership of the protocol including the principal investigator. Protocol many
Participant_Flows 28,997 Recruitment information relevant to the recruitment process & pre-assignment details (ie. significant events in the study that occur after participant enrollment, but prior to assignment of participants). Information about participant flow that applies to all milestones. Results one
Reported_Events 3,533,887 Summary information about reported adverse events (any untoward or unfavorable medical occurrence to participants, including abnormal physical exams, laboratory findings, symptoms, or diseases), including serious adverse events, other adverse events, and mortality. Results many
Responsible_Parties 239,849 People who have access to and control over the data from the study, have the right to publish study results, and have the ability to meet all of the requirements for the submission of study information. Protocol many
Result_Agreements 28,997 Info about whether an agreement exists between the sponsor & the principal investigators (PIs) that restricts the PIs ability to discuss study results at scientific meetings or other public or private forums, or to publish info concerning the study in scientific or academic journals after the study is completed. Results many
Result_Contacts 28,997 Point of contact for scientific information about the clinical study results information.  Results many
Result_Groups 693,471 Consolidated, aggregate list of group titles/descriptions used for reporting summary results information. Results many
Sponsors 408,042 Name of study sponsors and collaborators. The sponsor is the entity or individual initiating the study. Collaborators are other organizations providing support, including funding, design, implementation, data analysis, and reporting. Protocol many
Studies 259,453 Basic info about study, including study title, date study registered with ClinicalTrials.gov, date results first posted to ClinicalTrials.gov, dates for study start and completion, phase of study, enrollment status, planned or actual enrollment, number of study arms/groups, etc. Protocol & Results one
Study_References 313,442 Citations to publications related to the study protocol and/or results. Includes PubMed Unique Identifier (PMID) and/or full bibliographic citation.  Protocol many