Clinical trials: registration & reporting

Policy for the registration and transparent reporting of clinical trials submitted to IUMS medical journals, aligned with international standards on trial registries, CONSORT 2025 and data sharing expectations.

Applies to all interventional clinical trials submitted to IUMS journals
Policy v1.0 – last updated April 2025
Related policies: Research ethics & integrity · Research data & code sharing · Peer review · Corrections & retractions · Instructions for authors

1 Scope & definition of clinical trials

When IUMS journals consider a study to be a clinical trial.

For the purposes of this policy, IUMS journals adopt the widely used definition of a clinical trial as any research study that prospectively assigns human participants or groups of humans to one or more health-related interventions in order to evaluate effects on health outcomes. Health-related interventions include, for example, drugs, biologics, medical devices, surgical or anaesthetic procedures, behavioural or lifestyle interventions, diagnostic strategies, rehabilitation programmes and changes to systems of care.

This policy applies to all such interventional studies submitted to IUMS journals, regardless of:

  • disease area, intervention type or outcome;
  • study phase (from pilot and feasibility studies to phase IV);
  • funding source (public, private, non-profit or unfunded);
  • country of origin; or
  • whether the trial is single-centre or multicentre.

Observational studies that do not involve prospective assignment to an intervention (for example, cohort, case–control or cross-sectional designs) are not considered clinical trials for this policy, but must still follow the journal’s ethics and reporting requirements.

2 Which studies must be registered?

Registration is required for all interventional clinical trials submitted to IUMS journals.

IUMS journals require prospective registration of all clinical trials that fall within the definition above. The requirement includes, but is not limited to:

  • drug and biologic trials, regardless of marketing status;
  • device trials, including diagnostic devices and digital health interventions;
  • surgical and procedural trials;
  • behavioural, lifestyle, educational and rehabilitation interventions;
  • complex health service and systems-intervention trials.

Pilot, feasibility and proof-of-concept studies that prospectively assign participants to interventions are also expected to be registered, even if they do not aim to provide definitive efficacy estimates.

3 IUMS clinical trial registration policy

Registration is a condition for consideration of clinical trial manuscripts.

In line with international recommendations, IUMS journals require that clinical trials be registered in a public trial registry at or before the enrolment of the first participant as a condition for consideration of manuscripts reporting their results.

When submitting a manuscript that reports a clinical trial, authors must:

  • provide the name of the registry and the unique trial identifier;
  • confirm that registration occurred prospectively (before the first participant was enrolled);
  • ensure that the information in the registry record is complete and consistent with the manuscript; and
  • update the registry record when major protocol changes occur.

Trials that were not prospectively registered may be considered only in exceptional circumstances and must be clearly labelled as retrospectively registered, with a transparent explanation (see Section 9).

4 Acceptable clinical trial registries

Registries must meet WHO/ICMJE standards for public, searchable records.

To fulfil this policy, clinical trials must be registered in a registry that:

  • is publicly accessible and searchable at no cost;
  • has a mechanism to ensure the validity of core data elements;
  • is managed by a non-profit organisation or public entity;
  • complies with the World Health Organization (WHO) standards for primary registries; and/or
  • is recognised as acceptable by major journal groups that follow international recommendations.

Examples of such registries include, but are not limited to:

  • national primary registries participating in the WHO International Clinical Trials Registry Platform (ICTRP);
  • ClinicalTrials.gov;
  • IRCT.ir;
  • EU Clinical Trials Register / EUCTR;
  • ISRCTN registry; and
  • other WHO-recognised primary registries relevant to the region where the trial is conducted.

Authors should select a registry that is appropriate for their country and regulatory environment. Registering the same trial in more than one registry is acceptable, but one identifier should be designated as the primary registration number in the manuscript.

5 Timing & core registration data

Prospectively registered, with complete and consistent core items.

Registration should be completed before the first participant is enrolled. If initial registration records require later corrections, these should be made transparently without obscuring previous entries.

When registering a trial, investigators should ensure that at least the following core elements are included and kept up to date:

  • trial title and brief title;
  • primary sponsor and collaborating organisations;
  • health condition(s) under study;
  • intervention(s) and comparator(s);
  • study design (e.g. randomised, blinded, parallel group);
  • inclusion and exclusion criteria;
  • primary and key secondary outcomes, including timing of assessment;
  • planned sample size;
  • recruitment status and study start/end dates; and
  • contact details for the sponsor and principal investigator.

Many registries now also require a statement about future data sharing plans. This should be consistent with the journal’s Research data & code sharing policy and with the Data Availability Statement in the manuscript.

6 Trial identifiers in manuscripts

Where and how to report registration numbers in submissions.

The trial registration number must be clearly indicated in all submissions reporting the results of a registered trial. IUMS journals expect that:

  • the registry name and identifier appear at the end of the abstract (where word limits permit), and in the Methods section;
  • if several registrations exist, the primary registry and main identifier are specified; and
  • any differences between the registered protocol and the final manuscript (for example, changes to primary outcomes) are explicitly explained in the Methods or Discussion.

Reviewers and editors may cross-check registry entries against the submitted manuscript during assessment.

7 Reporting standards for clinical trials (CONSORT 2025)

Transparent trial reports using CONSORT and related extensions.

In addition to prospective registration, trials submitted to IUMS journals should be reported in line with CONSORT 2025 and relevant extensions. This includes using:

  • the main CONSORT checklist for individually randomised trials;
  • appropriate extensions for cluster randomised, non-inferiority or equivalence, pragmatic, pilot/feasibility, or multi-arm trials;
  • a participant flow diagram that clearly shows enrolment, allocation, follow-up and analysis; and
  • clear, explicit reporting of all primary and key secondary outcomes, including harms.

Authors should:

  • state in the Methods section that the report follows CONSORT or a relevant extension;
  • complete the CONSORT (and any extension) checklist; and
  • upload the checklist as a supplementary file at submission.

For non-randomised interventional studies, authors should follow relevant reporting guidelines (for example, TREND or other design-specific guidance) in addition to registration requirements.

8 Posting of results & data sharing

Aligning journal publication with registry results and data policies.

Many funders, regulators and registries require the posting of summary trial results in the registry within a defined timeframe after primary completion, regardless of journal publication. Authors are responsible for knowing and complying with these obligations.

IUMS journals support:

  • timely posting of summary results in the trial registry, consistent with the data reported in the manuscript;
  • transparent explanation of any differences between registry results and journal reports; and
  • sharing of de-identified individual participant data and analytic code when feasible, in accordance with the Research data & code sharing policy and ethical approvals.

Manuscripts should include a Data Availability Statement that is consistent with both ethics approvals and the information in the registry record.

9 Late or missing trial registration

How IUMS journals handle retrospective registration.

Ideally, all trials should be registered prospectively. However, journals sometimes receive manuscripts for trials that were registered late or not registered at all. In such cases:

  • authors must register the trial as soon as possible and provide the registry identifier;
  • the manuscript must clearly state that registration was retrospective and explain the reasons;
  • editors will consider the implications for scientific validity and research ethics on a case-by-case basis; and
  • late registration may negatively affect the chances of acceptance, especially where selective reporting or serious protocol deviations are suspected.

Trials that cannot be registered in a recognised public registry (for example, due to legal or regulatory constraints) will only be considered in exceptional circumstances and require explicit justification in the cover letter and manuscript.

10 Special cases & borderline designs

Substudies, secondary analyses and complex designs.

Some submissions relate to work that is connected to, but not identical with, a primary registered trial. Examples include:

  • pre-specified secondary analyses of trial data;
  • substudies focusing on specific outcomes, subgroups or biomarkers;
  • methodological or health economic analyses based on a trial; and
  • long-term follow-up of participants originally enrolled in a trial.

In these situations, authors should:

  • reference the primary trial registration number;
  • clarify whether the substudy or secondary analysis was detailed in the original registry entry;
  • explain any substantial departures from the original protocol; and
  • register the substudy separately if required by local regulations or funders, and if it involves new interventions or data collections outside the original scope.

When in doubt about whether a study counts as a clinical trial for this policy, authors are encouraged to contact the relevant journal before submission.

11 Roles & responsibilities

Who is responsible for ensuring compliance with this policy.

Responsibility for clinical trial registration and accurate reporting is shared, but specific roles are expected:

  • Principal investigator (PI): ensures that the trial is registered appropriately and that registry entries remain accurate and up to date.
  • Corresponding author: confirms, at submission, that trial registration is complete and that the registration number, registry name and data are correctly reported in the manuscript.
  • All authors: share responsibility for the integrity and transparency of the trial report, including registration and reporting of outcomes.
  • Editors: check trial registration details as part of the editorial process and may request clarifications or amendments before making a decision.
  • Reviewers: may flag inconsistencies between trial registration and the submitted manuscript, and raise concerns about reporting or protocol changes (see Guide for reviewers).

12 Editorial checks, audits & corrections

How issues with registration and reporting are handled.

If, during peer review or after publication, editors become aware of problems related to trial registration or reporting—for example:

  • unregistered or retrospectively registered trials;
  • major discrepancies between registered and reported outcomes;
  • selective non-reporting of prespecified outcomes; or
  • evidence of serious protocol deviations not disclosed in the manuscript,

they may take actions that include:

  • requesting detailed explanation and amendments from authors;
  • requiring an updated or corrected registry record;
  • publishing a correction, addendum or editorial note to clarify the record; or
  • in severe cases, rejecting the manuscript or, if already published, following the procedures described in the Corrections, retractions & withdrawals and Misconduct policies.

Where appropriate, journals may inform relevant institutions, funders or regulatory bodies in line with established procedures.

13 Questions & contact

Getting help with registration or reporting of clinical trials.

Authors who are uncertain whether their study meets the definition of a clinical trial, or who need guidance on registration and reporting requirements, are encouraged to contact the editorial office of the target IUMS journal before submission.

General questions about this policy across IUMS journals can be directed to:

Policy version: v1.0 – last updated April 2025. This page will be reviewed periodically to reflect evolving international standards for clinical trial registration and reporting.