Characteristics of Clinical Trials Registered in ClinicalTrials.gov, 2007-2010

JAMA. 2012 May 2;307(17):1838-47. doi: 10.1001/jama.2012.3424.

Abstract

Context: Recent reports highlight gaps between guidelines-based treatment recommendations and evidence from clinical trials that supports those recommendations. Strengthened reporting requirements for studies registered with ClinicalTrials.gov enable a comprehensive evaluation of the national trials portfolio.

Objective: To examine fundamental characteristics of interventional clinical trials registered in the ClinicalTrials.gov database.

Methods: A data set comprising 96,346 clinical studies from ClinicalTrials.gov was downloaded on September 27, 2010, and entered into a relational database to analyze aggregate data. Interventional trials were identified and analyses were focused on 3 clinical specialties-cardiovascular, mental health, and oncology-that together encompass the largest number of disability-adjusted life-years lost in the United States.

Main outcome measures: Characteristics of registered clinical trials as reported data elements in the trial registry; how those characteristics have changed over time; differences in characteristics as a function of clinical specialty; and factors associated with use of randomization, blinding, and data monitoring committees (DMCs).

Results: The number of registered interventional clinical trials increased from 28,881 (October 2004-September 2007) to 40,970 (October 2007-September 2010), and the number of missing data elements has generally declined. Most interventional trials registered between 2007 and 2010 were small, with 62% enrolling 100 or fewer participants. Many clinical trials were single-center (66%; 24,788/37,520) and funded by organizations other than industry or the National Institutes of Health (NIH) (47%; 17,592/37,520). Heterogeneity in the reported methods by clinical specialty; sponsor type; and the reported use of DMCs, randomization, and blinding was evident. For example, reported use of DMCs was less common in industry-sponsored vs NIH-sponsored trials (adjusted odds ratio [OR], 0.11; 95% CI, 0.09-0.14), earlier-phase vs phase 3 trials (adjusted OR, 0.83; 95% CI, 0.76-0.91), and mental health trials vs those in the other 2 specialties. In similar comparisons, randomization and blinding were less frequently reported in earlier-phase, oncology, and device trials.

Conclusion: Clinical trials registered in ClinicalTrials.gov are dominated by small trials and contain significant heterogeneity in methodological approaches, including reported use of randomization, blinding, and DMCs.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cardiovascular Diseases / therapy
  • Clinical Trials as Topic / standards*
  • Clinical Trials as Topic / statistics & numerical data*
  • Databases, Factual*
  • Drug Industry
  • Humans
  • Mental Disorders / therapy
  • National Institutes of Health (U.S.)
  • Neoplasms / therapy
  • Randomized Controlled Trials as Topic
  • Registries / statistics & numerical data*
  • Research Design
  • Research Support as Topic
  • Sample Size
  • United States