Analysis: More Studies on, but Crucial Data Missing


More researchers are registering their studies with the database, but the federal website still is missing certain important data, according to an analysis published in the Journal of the American Medical Association, MedPage Today reports.

Background on was launched in 1997 to help people gain access to information on clinical trials. In 2004, an international organization of medical editors agreed that registration in a registry should be a prerequisite for a study's publication (Smith, MedPage Today, 5/1).

In 2007, FDA issued rules requiring researchers to publish a results summary on for all eligible clinical trials within a year of the study's completion (iHealthBeat, 1/5).

Details of Analysis

For the analysis, researchers at the Duke Translational Medicine Institute downloaded all studies registered with the site through Sept. 27, 2010.

Their analysis focused on 79,413 interventional trials related to oncology, cardiology and mental illness. The researchers compared studies registered between October 2004 and September 2007 with those registered between October 2007 and September 2010.

Key Findings

The analysis found that the number of trials submitted for registration increased from 28,881 in the earlier period to 40,970 in the later period.

The analysis also found that fewer trials in the later period failed to report:

  • Use of a data monitoring committee;
  • Enrollment numbers; and
  • Randomization or blinding.

However, the analysis found that 6.8% of trials in the later years failed to report the primary purpose of the study, compared with 4.6% in the earlier period.

Researchers also found significant variation in methods. For example, they determined that trials sponsored by NIH were more likely to report having a data monitoring committee than those sponsored by the health care industry.

Response to Findings

Researchers wrote that the significant differences among trials and over time raise "fundamental questions about the ability to draw reliable inferences from clinical research conducted in that arena."

Kay Dickersin of the Johns Hopkins Bloomberg School of Public Health and Drummond Rennie of the University of California-San Francisco in an accompanying editorial wrote, "Despite important progress, is coming up short, in part because not enough information is being required and collected, and even when investigators are asked for information, it is not necessarily provided" (MedPage Today, 5/1).

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