Article Snapshot: JAMA: Characteristics of clinical trials registered in, 2007-2010

Posted On 2012-05-09 13:55:36
In this paper recently published in JAMA, the authors from the Duke Translational Medicine Institute examine the characteristics of clinical trials registered in the US clinical trial database ‘’ (1). The authors describe that recent reports have highlighted gaps between guidelines-based treatment recommendations and supporting evidence from clinical trials.  To further understand these discrepancies, a data set comprising 96,346 clinical studies was downloaded from ‘’ in September 2010 and analyzed. Interventional trials were identified and separated according to clinical specialties of cardiovascular, mental health, and oncology. The authors evaluated the characteristics of registered clinical trials in the overall group and in the individual clinical specialty. Furthermore the change of these characteristics was evaluated in two time periods. 

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 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, 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):

- US:

- EU: EU Clinical Trials Register :

- China : Chinese Clinical Trial Registry:

- Australian Clinical Trials Registry:

- Clinical Trials Registry – India:

- UMIN Clinical Trials Registry (UMIN-CTR):