Data from: Terminated trials in the ClinicalTrials.gov results database: evaluation of availability of primary outcome data and reasons for termination

Background: Clinical trials that end prematurely (or “terminate”) raise
financial, ethical, and scientific concerns. The extent to which the
results of such trials are disseminated and the reasons for termination
have not been well characterized. Methods and Findings: A cross-sectional,
descriptive study of terminated clinical trials posted on the
ClinicalTrials.gov results database as of February 2013 was conducted. The
main outcomes were to characterize the availability of primary outcome
data on ClinicalTrials.gov and in the published literature and to identify
the reasons for trial termination. Approximately 12% of trials with
results posted on the ClinicalTrials.gov results database (905/7,646) were
terminated. Most trials were terminated for reasons other than accumulated
data from the trial (68%; 619/905), with an insufficient rate of accrual
being the lead reason for termination among these trials (57%; 350/619).
Of the remaining trials, 21% (193/905) were terminated based on data from
the trial (findings of efficacy or toxicity) and 10% (93/905) did not
specify a reason. Overall, data for a primary outcome measure were
available on ClinicalTrials.gov and in the published literature for 72%
(648/905) and 22% (198/905) of trials, respectively. Primary outcome data
were reported on the ClinicalTrials.gov results database and in the
published literature more frequently (91% and 46%, respectively) when the
decision to terminate was based on data from the trial. Conclusions:
Trials terminate for a variety of reasons, not all of which reflect
failures in the process or an inability to achieve the intended goals.
Primary outcome data were reported most often when termination was based
on data from the trial. Further research is needed to identify best
practices for disseminating the experience and data resulting from
terminated trials in order to help ensure maximal societal benefit from
the investments of trial participants and others involved with the study.