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Primary completion date

Primary completion date is the date that the final subject was examined or received an intervention for the purposes of final collection of data for the primary outcome, whether the clinical trial concluded according to the pre-specified protocol or was terminated.[1] This definition comes from US rules on registering clinical trials with ClinicalTrials.gov, a registry run by the US National Library of Medicine at the National Institutes of Health.[1][2]

Where a trial has more than one primary outcome measure with different completion dates, the date is the one on which data collection is completed for all of the primary outcomes.[1] The primary outcome measure is the outcome measure of greatest importance specified in the protocol, usually the one used in the power calculation.[1] Most clinical trials have one primary outcome measure, but a trial may have more than one.[1]

Under the US ClinicalTrials.gov rules, the primary completion date recorded for a trial can be either estimated or actual.[1] If an estimated date is used, the responsible party must update it to the actual primary completion date once the trial has reached it.[1] At that point the responsible party must also update the enrolment figure to the actual number of human subjects enrolled.[1]

Why it matters to investors

Under the US rules, a clinical trial of a drug product counts as ongoing on a given date if one or more human subjects are enrolled and the date is before the primary completion date.[1] A date that was only an estimate must be replaced with the actual date once the trial reaches it, so the registered date can change over a trial's life.[1]

Sources

  1. 42 CFR § 11.10 – Definitions (US Code of Federal Regulations, Clinical Trials Registration and Results Information Submission). Legal Information Institute, Cornell Law School law.cornell.edu
  2. "ClinicalTrials.gov Logo" . ClinicalTrials.gov . Archived from the original on December 18, 2020 . Retrieved February 9, 2015 . clinicaltrials.gov (via Wikipedia: ClinicalTrials.gov)

Checked 8 October 2026. How we check sources