Examples
Worked examples
- Is an instance
A pharmaceutical sponsor registers a Phase 2 drug trial on ClinicalTrials.gov before enrolling its first participant, receiving an NCT number that is then cited to identify the trial in any resulting journal manuscript and in the later results-reporting record.
- Is an instance
An academic trial conducted primarily in the UK registers with ISRCTN — a WHO ICTRP-recognized primary registry — rather than ClinicalTrials.gov; this still satisfies ICMJE's registry-acceptability criteria, because those criteria require registration with any qualifying WHO primary registry, not specifically with ClinicalTrials.gov.
Counter-examples
Looks similar, but isn't
- Not an instance
Posting a trial protocol to a preprint server or the sponsoring institution's own website, even with a timestamp, is not registration in this sense — it is not captured in a structured, publicly searchable registry meeting the WHO Trial Registration Data Set, so it cannot be cited as satisfying ICMJE, FDAAA 801, or NIH registration requirements.
- Not an instance
Pre-registering the hypotheses and statistical analysis plan of a study that is not itself a clinical trial (for example, a psychology lab experiment) on a general research-transparency platform such as OSF Preregistration or AsPredicted is pre-registration as a broader methodological practice — not clinical trial registration, which applies specifically to interventional trials recorded in a WHO/ICMJE/FDAAA-qualifying clinical-trial registry.
Editorial commentary
Clinical trial registration is the baseline transparency mechanism underlying most modern clinical-research policy: a trial cannot be selectively reported, quietly abandoned without a public trace, or have its design retroactively altered to fit favorable results if its existence, design, and pre-specified outcomes were already on the public record before it produced any data. This is the rationale cited by the International Committee of Medical Journal Editors (ICMJE) for its registration policy, in effect for trials beginning enrollment on or after 1 July 2005, and it underlies the separate, later U.S. statutory requirement created by FDAAA 801 (2007) and the companion NIH Policy on the Dissemination of NIH-Funded Clinical Trial Information (both effective 18 January 2017).
Registration is distinct from results reporting — posting outcome data to the same registry after the trial concludes — which is a separate obligation with its own deadline (12 months after primary completion, under FDAAA 801). It is also distinct from prospective registration specifically, i.e. completing registration before enrollment begins rather than retrospectively at manuscript submission; ICMJE’s policy requires the prospective form. And it is a narrower concept than general research pre-registration, which covers pre-specifying a study’s hypotheses and analysis plan across any research discipline, not only interventional clinical trials on a qualifying registry.
For the specific deadlines, enforcement mechanisms, and the genuine differences between ICMJE’s, FDAAA’s, and NIH’s definitions of which trials are covered, see CASRAI’s clinical trial registration and reporting compliance guide.
Frequently Asked Questions
What information does a clinical trial registration have to include?
A registration must include the trial’s identifying and design information — the sponsor, the condition studied, the intervention, key eligibility criteria, and the primary and secondary outcome measures — submitted to a recognized public registry such as ClinicalTrials.gov or another WHO ICTRP primary registry.
Which registries count as a clinical trial registry for ICMJE purposes?
Any WHO ICTRP primary registry qualifies, not only ClinicalTrials.gov. For example, an academic trial conducted mainly in the UK can register with ISRCTN — a WHO ICTRP-recognized primary registry — and still satisfy ICMJE’s registry-acceptability criteria.
When must a clinical trial be registered?
Under ICMJE’s policy, trials beginning enrollment on or after 1 July 2005 must be registered. Separate obligations also apply under the U.S. FDAAA 801 statute and the NIH Policy on the Dissemination of NIH-Funded Clinical Trial Information, both effective 18 January 2017. For the exact deadlines and how these frameworks differ in which trials they cover, see CASRAI’s clinical trial registration and reporting compliance guide.
Is registering a clinical trial the same as reporting its results?
No. Registration identifies the trial before or during its conduct, while results reporting — posting outcome data to the same registry after the trial concludes — is a separate, later obligation with its own deadline (12 months after primary completion under FDAAA 801).
What’s the difference between clinical trial registration and prospective registration?
Clinical trial registration is the general act of submitting a trial to a qualifying registry. Prospective registration specifically means completing that registration before enrollment begins, rather than retrospectively at manuscript submission — the form ICMJE’s policy requires. See CASRAI’s entry on prospective clinical trial registration for more detail.
Does registering a trial give it an identification number?
Yes. When a sponsor registers a trial on ClinicalTrials.gov, the registry assigns it an NCT number, which is then used to identify the trial in any resulting journal manuscript and in the later results-reporting record. Other WHO ICTRP primary registries similarly assign their own trial identifiers.
Machine-readable encodings
Use in your systems
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