CONSORT Checklist: Reporting a Randomised Trial

The CONSORT checklist is the reporting standard for randomised controlled trials, and the current version is CONSORT 2025, which carries 30 items and replaces the 25-item CONSORT 2010 statement. Its name stands for Consolidated Standards Of Reporting Trials. Its purpose is narrow and useful: make the report complete enough that a reader can judge whether the trial's result is believable, and apply it to somebody outside the study.

CONSORT concentrates hard on the small number of mechanisms that separate a trial from an observational comparison. How was the allocation sequence generated. How was it concealed from the people doing the recruiting. Who was blinded, and to what. What happened to every participant who was randomised. A trial can be large, expensive and well conducted, and still be unusable in a synthesis because those four things were described loosely.

What changed from CONSORT 2010

The move from 25 items to 30 is not a wholesale rewrite, and a paper written carefully against the 2010 statement will not be far off. What the update does is make explicit a set of expectations that had drifted into practice informally, and give them item numbers so they stop being optional. The practical consequences for authors are about emphasis: more explicit treatment of harms, clearer expectations around open science matters such as data availability and protocol access, more direct attention to who the trial was conducted with including patient and public involvement, and tighter wording on the description of the intervention so it could be replicated.

The operational lesson is simpler than the content. Name the version you followed in your methods. A reviewer working from the 2010 checklist and an author working from the 2025 one will disagree about which items are missing, and the disagreement is resolved by one sentence.

The 30 items, section by section

The items track the structure of a trial report, so working through them in order also tests the paper's organisation. What follows describes what each section asks for in our own words. The authoritative wording and the official files sit with the CONSORT and SPIRIT group, and should be downloaded from there rather than copied from a secondary summary.

Title and abstract. That the report be identifiable as a randomised trial, and that the abstract give a structured summary of design, methods, results and conclusions. Abstracts have their own extension, because the space constraints make the core items impractical.

Introduction. The scientific background and rationale for the comparison, and specific objectives or hypotheses.

Methods. The largest section, covering the trial design and any changes to it after commencement with reasons, the setting and locations, participant eligibility, the interventions for each group in enough detail to allow replication, completely defined prespecified primary and secondary outcomes including how and when they were assessed and any changes to them after the trial began, how the sample size was determined including any interim analyses and stopping guidelines, the method used to generate the random allocation sequence with any restriction such as blocking or stratification, the allocation concealment mechanism, who was blinded after assignment and how, and the statistical methods for primary and secondary outcomes together with any subgroup or adjusted analyses.

Results. Participant flow for each group with the numbers randomised, receiving the intended treatment and analysed for the primary outcome, losses and exclusions with reasons, the dates of recruitment and follow-up, why the trial ended or stopped, baseline characteristics by group, the numbers included in each analysis and whether the analysis was by original assigned group, the results for each outcome with the effect size and its precision, the results of any other analyses distinguishing prespecified from exploratory, and all important harms or unintended effects.

Discussion. Trial limitations including sources of potential bias and imprecision, generalisability, and an interpretation consistent with the results that balances benefits and harms against other evidence.

Other information. Where the full trial protocol can be accessed, the registration number and registry, sources of funding and other support, and the role of funders.

The flow diagram is part of the guideline

Authors sometimes treat the diagram as a nice-to-have. It is an item, and it does work no paragraph does as well: it forces the numbers to reconcile. Four stages are tracked. Enrolment, with the number assessed for eligibility and the number excluded with reasons. Allocation, with the number assigned to each group and the number who actually received the allocated intervention. Follow-up, with losses and discontinuations for each group and their reasons. Analysis, with the number included in the primary analysis for each group and any exclusions with reasons.

The reason reviewers go to the diagram first is that it makes an intention to treat claim checkable. If 240 participants were randomised and 218 appear in the analysis, the diagram has to say where 22 people went. If it does not, the claim that the analysis preserved the randomisation cannot be assessed, and the trial's central protection against bias becomes an assertion. We use the same logic in evidence synthesis, where the PRISMA flow diagram generator plays the equivalent role for records rather than participants.

Choose the extension that fits your trial

Reporting a specialised trial against the core checklist is a common own goal, because the items that matter most in your design may not appear in the core statement at all. Extensions exist for cluster randomised trials, where the unit of allocation is a clinic or school rather than a person and the analysis must account for clustering; pilot and feasibility trials, where the objective is not a treatment effect; non-inferiority and equivalence trials, where the margin has to be justified in advance; pragmatic trials; N-of-1 trials; stepped wedge designs; and trials reporting patient-reported outcomes, harms, or herbal and non-pharmacological interventions. There are further extensions covering artificial intelligence interventions and abstracts.

Find the current list through the EQUATOR Network guideline library, cite the extension rather than the core statement where one applies, and say which you used.

CONSORT, SPIRIT, and the value of doing them in order

CONSORT reports a trial that has happened. SPIRIT 2025, with its 34 items, covers the protocol written before it happens. They are deliberately aligned, and using them in sequence is what makes a trial report verifiable rather than merely complete: the outcomes, sample size justification and analysis plan a reader checks in your final paper are the ones you committed to in advance.

The same relationship holds elsewhere in research reporting. A systematic review has PRISMA-P for the protocol and PRISMA 2020 for the report. An observational study has no protocol guideline of the same status, which is one reason the STROBE checklist leans so heavily on asking authors to distinguish prespecified analyses from those decided later.

Completing the checklist without wasting the exercise

Fill it in against the final manuscript, and record the page and section for every item instead of ticking it. A page number can be checked; a tick cannot, and reviewers have learned to distrust a checklist of unbroken ticks. Where an item does not apply, write not applicable with a short reason rather than leaving a gap.

Then use it as a self-review. In our experience the items that most often cannot be pointed to a page are allocation concealment, changes to outcomes after the trial began, and harms. Those are also three of the four things a methodological reviewer will look for first, so the checklist has already told you where the revision request is coming from.