How to Create a CONSORT 2025 Flow Diagram for an RCT

A CONSORT flow diagram gives readers a concise visual account of what happened to participants in a randomized controlled trial. It shows how many people were assessed, randomized, allocated to each intervention, followed for the primary outcome, and included in the primary analysis. It should also make losses and exclusions transparent.

The CONSORT 2025 statement supersedes CONSORT 2010 and includes an updated flow diagram for reporting randomized trials. The standard diagram follows four broad phases: enrolment, intervention allocation, follow-up, and data analysis.

Create your CONSORT 2025 flow diagram with the Blazon Scientific Study Flow Diagram Builder. You can build and validate the diagram for free before deciding whether to unlock publication-ready exports.

What should a CONSORT 2025 flow diagram contain?

For a conventional two-group parallel randomized trial, the participant-flow diagram should allow the reader to follow participants from initial assessment through to the primary analysis. The exact content can be adapted to the design of the trial, but the major stages usually include the following.

1. Enrolment

Start with the number of individuals who were assessed for eligibility, where that number is known. Then report how many were excluded before randomization and, where relevant, the reasons for exclusion.

Common reasons include:

• not meeting eligibility or inclusion criteria;
• declining to participate; and
• other prespecified or relevant reasons.

The final enrolment box should show the number of participants who were randomized.

2. Intervention allocation

After randomization, show the number allocated to each trial group. For each group, report how many participants received the intended intervention and how many did not receive the intended intervention, with reasons where appropriate.

This distinction matters because the number randomized to a group is not always the same as the number who actually begin or receive the assigned intervention.

3. Follow-up

For each randomized group, document important events after allocation. CONSORT 2025 distinguishes participant follow-up for the primary outcome from other post-randomization events. Relevant information can include:

• participants who discontinued the intervention, with reasons;
• participants lost to follow-up for the primary outcome, with reasons where known; and
• other design-specific events required to understand what happened to participants.

Do not automatically treat intervention discontinuation and loss to follow-up as the same thing. A participant may stop the assigned intervention but still provide primary-outcome data.

4. Analysis

For each group, report the number of participants analysed for the primary outcome. If participants were excluded from that analysis, report the number excluded and the reasons.

The diagram should make it possible to reconcile the main participant counts. Readers should not have to infer where participants disappeared between randomization and analysis.

How to check the arithmetic in a CONSORT flow diagram

Before submitting a manuscript, check that the participant counts are internally consistent. Useful checks include:

• assessed for eligibility minus pre-randomization exclusions should reconcile with the number randomized, unless there is another explicitly reported stage;
• the numbers allocated across all groups should reconcile with the randomized total;
• within each group, the numbers receiving and not receiving the allocated intervention should be consistent with the number allocated;
• losses, exclusions and analysed participants should be accounted for clearly; and
• the numbers shown in the diagram should agree with the abstract, Results section, tables and supplementary material.

The Blazon Scientific Study Flow Diagram Builder performs live participant-count checks while you construct the diagram, helping identify totals that do not reconcile.

Does every RCT need exactly the same flow diagram?

No. CONSORT 2025 provides a standard model, but the explanation and elaboration document notes that the exact form and content can be adapted to the specific features of a trial. Some designs may require additional information, while some standard boxes may not be relevant.

Examples include cluster-randomized trials, multi-arm trials, trials involving centres or care providers, and interventions where treatment discontinuation is not meaningful in the usual sense. Relevant CONSORT extensions should also be consulted when they apply to the trial design.

Common CONSORT flow-diagram mistakes

• Using CONSORT 2010 as the current standard. CONSORT 2025 has superseded the 2010 statement.
• Combining different post-randomization events. Treatment discontinuation, loss to primary-outcome follow-up and exclusion from analysis are not necessarily interchangeable.
• Reporting totals that do not reconcile. This creates uncertainty about the analysis population.
• Omitting reasons for losses or exclusions. Reasons can be important when readers assess the risk and possible direction of attrition-related bias.
• Showing a diagram that conflicts with the manuscript text. Participant numbers should be consistent across all parts of the report.

How to make a CONSORT flow diagram

1. Collect the participant counts for enrolment, allocation, follow-up and analysis.
2. List the reasons for exclusions, non-receipt of intervention, losses to follow-up and analysis exclusions.
3. Check that the totals reconcile.
4. Enter the information into a structured flow-diagram template.
5. Review the diagram against CONSORT 2025 and any relevant CONSORT extension.
6. Export a publication-ready figure and check that it remains legible at the journal’s final figure size.

Ready to build the figure? Open the CONSORT & STROBE Study Flow Diagram Builder.

References and further guidance

• CONSORT 2025 statement: updated guideline for reporting randomised trials.
• CONSORT 2025 explanation and elaboration.

This guide supports transparent reporting but does not determine whether a manuscript as a whole is CONSORT compliant. Authors should consult the complete CONSORT 2025 statement, explanation and elaboration document, and relevant extensions.