How Often are Registered Clinical Trials Publishing Their Results?


Study examines how many registered clinical trials with published protocols are also publishing their results.

Image Credit: © FlowStudio -

Image Credit: © FlowStudio -

A commentary recently published on JAMA Network examined how often registered clinical trials are publishing their results.1 The cross-sectional study analyzed 308 clinical trial protocols published on PubMed Central from 2011 to 2022.

“This study suggests that many published trial protocols are not associated with published trial results, but the overall benefits of publishing protocols might outweigh the research waste caused by unnecessary protocol publications,” the authors wrote.

One of the largest benefits associated with publishing clinical trial protocols is promoting transparency. Published protocols also increase efficiency, while decreasing research waste; however, there are both pros and cons to prospectively publishing protocols, according to the authors.

“Publishing or posting protocols prospectively might help reduce research waste because of unclear methods or incomplete reporting of results,” the authors wrote. “On the other hand, publishing or posting protocols prospectively could contribute to unblinding, deviations from intended interventions, or biased outcomes assessment.”

Return on investment is also a consideration when it comes to publishing protocols in journals. The authors bring attention to the fact that open access journals often charge thousands of dollars for publishing. There is also a significant amount of time spent on drafting and reviewing the protocols.

“For trials that are never performed or never published, the money and time spent publishing study protocols might be wasted,” the authors wrote.

The weighted analysis estimated that 36% of eligible clinical trial protocols published between 2011 and 2022 were not associated with main results publication. Some of the characteristics of these trials mentioned in the study were that trial status was marked as completed for 236, but 56 had indicated an unknown status. Over half of the trials (64%) described their phase as unapplicable.

“This study highlights deficiencies in the reporting of clinical trials. For example, we were unable to determine the status of many unpublished trials because information on was often outdated and because some investigators did not respond to requests for information,” the authors wrote.

While the study analysis shows there is inconsistency in the publishing of trial results, the benefits of publishing the protocols may still outweigh resource costs. “Because trials can be costly and impactful, reducing waste from only a few trials could avoid millions of dollars in wasted research or health care spending,” the authors wrote.

The study had two noteworthy limitations. The first is that the authors utilized information investigators provided to, some of which was outdated. Second, results from 25 trials were unable to be located.

“Moreover, many trials did not adhere to best practices for registering and reporting their status and results,” the authors concluded. “Despite these deficiencies, the benefits of publishing trial protocols probably outweigh the associated research waste.”


  1. Vorland CJ, Brown AW, Kilicoglu H, Ying X, Mayo-Wilson E. Publication of Results of Registered Trials With Published Study Protocols, 2011-2022. JAMA Netw Open. 2024;7(1):e2350688. doi:10.1001/jamanetworkopen.2023.50688
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