Federal law requires the registration of all non-phase 1 interventional trials of drugs, biologics, or devices that were initiated after September 27, 2007, or before that date but that were still ongoing as of December 26, 2007, have at least one U.S. research site, or are conducted under an investigational-new-drug application or an investigational-device exemption. ClinicalTrials.gov is a registry of human clinical research studies hosted by the U.S. National Institutes of Health, through its National Library of Medicine (NLM), in collaboration with the Food and Drug Administration (FDA). Studies listed in the database are conducted in all 50 US states and in 174 countries. The purpose of ClinicalTrials.gov is to provide a central resource for those seeking information on individual clinical research projects and to increase visibility of human subjects' research. While this database has been useful for patients to identify potential clinical trials in which to participate, researchers were not able to effectively access and analyze the data to learn about the characteristics and effectiveness of clinical trials as a whole. Issues related to data structure, nomenclature, and changes in data collection over time presented challenges to the aggregate analysis and interpretation of these data in general and to the analysis of trials according to clinical specialty in particular.

State of Clinical Trials: “Improving the Public Interface for Use of Aggregate Data in ClinicalTrials.gov” (2010 - Ongoing)

CTTI sought to enhance the utility of ClinicalTrials.gov as a research resource by creating a restructured version of the database that analysts could more easily use to study various aspects of US clinical trials, including the following:

• Understanding the current state of clinical trials as a whole
• Comparing trials within or between different medical specialties, such as oncology, pediatrics, or cardiology
• Looking for unmet need in a particular specialty
• Seeing what’s already been done in a specialty before designing another trial in that specialty

Improving the usability of the data found on ClinicalTrials.gov could enhance its utility as a research resource.

With CTTI’s contribution of AACT, this publicly-accessible dataset will facilitate analysis of studies and permit detailed characterization and analysis of the US clinical trials enterprise as a whole; the methodology for creating specialty datasets may facilitate other efforts to analyze studies by specialty groups.

• Creation of AACT that include the following key design features:
  • the capacity to extend the dataset by parsing existing data
  • linking to additional data resources, such as the Medical Subject Headings (MeSH) thesaurus
  • integrated metadata
• Developed a methodology to re-group studies from ClinicalTrials.gov by clinical specialties as designated by the Department of Health and Human Services.

Detailed methodology on the creation AACT and the re-grouping of clinical studies can be found in the 2012 PLoS ONE publication.

The efforts of this CTTI project resulted in the AACT database, which allows researchers and analysts to perform analyses on a study dataset (a group of several studies) and not just within an individual study. Data from 2010 provided CTTI with a snapshot of the state of clinical trials, which showed that the clinical trial enterprise is dominated by small clinical trials, many of which are not funded by the NIH or industry, and contains significant heterogeneity in methodological approaches that typically do not provide enough robust data to guide critical medical decisions. High-quality evidence is still needed to guide medical decisions; this analysis reinforced the need to evaluate a number of aspects of the clinical trial enterprise.

CTTI also created a method to identify and group the clinical trials by specialty, such as pediatrics, infectious diseases, etc. This helps researchers know which trials have been completed in each medical specialty, or to compare trials between specialties—for example, to compare the average number of participants in cardiovascular trials to those in oncology trials. In addition to the AACT database itself, CTTI created a detailed data dictionary that provides documentation about the source, coding, and history of variables collected in AACT; a high level data dictionary containing a summary of these variables; and guidelines to consider when planning a statistical analysis of the ClinicalTrials.gov database.

The Points to Consider document provides guidelines for investigators to consider when planning a statistical analysis of the ClinicalTrials.gov database. Examples of analyses conducted using the AACT database can be in CTTI publications detailed on our products list.