The authors report that the number of registered interventional clinical trials increased from 28,881 (2004- 2007) to 40,970 (2007- 2010), and the number of missing data elements 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 were found relative to clinical specialty; sponsor type; and reported use of data monitoring committees (DMCs). 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.
The authors conclude that the 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.
An accompanying editorial describes the historical evolution of clinical trial registries in the US (2). It is noteworthy, that such registries exist worldwide (3) and provide public access to ongoing medical research.
1. Califf RM, Zarin DA, Kramer JM, Sherman RE, Aberle LH, Tasneem A. Characteristics of clinical trials registered in ClinicalTrials.gov, 2007-2010. JAMA. 2012 May 2;307(17):1838-47.
2. Dickersin K, Rennie D. The evolution of trial registries and their use to assess the clinical trial enterprise. JAMA. 2012 May 2;307(17):1861-4.
3. Clinical Trial Registries:
- WHO: International Clinical Trials Registry Platform (ICTRP): http://www.who.int/ictrp/en/
- US: ClinicalTrials.gov: http://www.clinicaltrials.gov/
- EU: EU Clinical Trials Register : https://www.clinicaltrialsregister.eu/
- China : Chinese Clinical Trial Registry: http://www.chictr.org/en/
- Australian Clinical Trials Registry: http://www.actr.org.au
- Clinical Trials Registry – India: http://ctri.nic.in/Clinicaltrials/
- UMIN Clinical Trials Registry (UMIN-CTR): http://www.umin.ac.jp/ctr/