How to Prepare a Lay Summary of Clinical Trial Results

Published on 22/12/2025

Creating Clear and Compliant Lay Summaries of Clinical Trial Results

Table of Contents

Introduction: Why Lay Summaries Matter

Lay summaries—also called plain language summaries—are short, readable documents that communicate the results of a clinical trial to the general public. Required under the EU Clinical Trials Regulation (EU CTR), and encouraged globally, lay summaries increase transparency, uphold participant rights, and promote public understanding of clinical research.

Unlike technical study reports or journal articles, lay summaries must be free of jargon, written at a B1/B2 reading level, and structured to clearly explain what was done, what was found, and what it means. This article outlines the formatting standards, timelines, structure, and tools for writing effective and compliant lay summaries.

EU CTR Requirements for Lay Summaries

Under Regulation (EU) No. 536/2014, all interventional trials conducted in the EU must include a lay summary submitted through the Clinical Trials Information System (CTIS). Key requirements include:

Deadline: Submitted within 12 months of trial completion (6 months for pediatric trials)
Format: Uploaded as a PDF to CTIS, alongside technical results
Language: In the official language(s) of each participating country
Structure: Follows EMA-recommended 10-section format (see below)

Lay summaries are published automatically unless a justified deferral is

approved, making readability and content accuracy critically important.

10 Recommended Sections of a Lay Summary (EMA Template)

The European Medicines Agency (EMA) suggests the following structure for lay summaries:

Trial Identifier: Trial number, title, and registry ID (e.g., EudraCT)
Purpose of the Trial: The disease and objective of the study
Who Participated: Summary of participant demographics and criteria
What Treatment Was Given: Interventions and how they were administered
What Was Measured: Primary and secondary outcomes
Results of the Trial: Key findings with simple visuals or percentages
Side Effects: Common and serious adverse events explained in lay terms
Conclusion: What the findings mean for future care or research
Where to Learn More: Trial registry links and sponsor contact info
Glossary: Definitions of any unavoidable medical terms

Each section should be 2–4 paragraphs and use short, direct sentences for clarity.

Readability and Language Expectations

Lay summaries must be written at a B1/B2 CEFR level, equivalent to an 8th-grade reading level. This ensures accessibility to most of the general population. Tips for maintaining proper readability include:

Use active voice and avoid passive constructions
Replace technical terms with simpler alternatives (e.g., “high blood pressure” instead of “hypertension”)
Limit sentence length to 15–20 words
Use bulleted or numbered lists where appropriate
Define complex words in parentheses or glossary

Free tools like Hemingway Editor, Readable.com, and Microsoft Word’s built-in readability checker can assess compliance with B-level standards.

Visual Aids and Formatting

Visuals enhance comprehension for lay readers. When permitted by the registry, include:

Simple bar charts or pie charts for results comparison
Infographics to explain trial flow or study design
Color-coded adverse event severity graphs

Always ensure images are captioned, accessible, and printable in grayscale. Avoid clinical imagery that may cause confusion or concern.

Translation for Multinational Trials

If a trial is conducted across multiple EU member states, the lay summary must be submitted in all applicable official languages. Considerations include:

Using certified medical translators familiar with plain language principles
Conducting back-translations to verify accuracy
Adding region-specific terminology if relevant

In some cases, translation costs and workflows can be centralized using CROs or localization vendors with EU CTR experience.

Timeline Integration and Planning

Lay summaries should be written before the trial completes, so they’re ready for submission alongside the technical results. Planning tips:

Assign summary drafting to medical writers or patient engagement experts
Use a shared template across all trials for consistency
Pre-fill non-result sections (e.g., trial purpose, eligibility) early
Set internal deadlines at least 30 days before CTIS submission deadlines

Late or missing lay summaries can delay trial publication in CTIS and trigger regulatory attention.

Common Mistakes and How to Avoid Them

Overuse of jargon: Even common clinical terms may be unfamiliar to the public
Incomplete safety explanations: Explain both minor and serious side effects clearly
Neglecting the “what it means” section: Readers need context, not just numbers
Too short or too long summaries: 4–6 pages total is ideal
Missing trial ID or registry link: Required for public verification

Review summaries with patient advocates or advisory boards for clarity before submission.

Best Practices Checklist

✔ Use EMA’s 10-section structure
✔ Write at CEFR B1/B2 level
✔ Submit within 12 months of trial completion
✔ Provide multilingual versions for EU states
✔ Review with a non-specialist reader before submission
✔ Link to registry and sponsor contact for questions

These practices ensure legal compliance, ethical communication, and meaningful public engagement with clinical research.

Conclusion: Lay Summaries Empower Public Trust

Lay summaries are a key component of modern trial transparency. More than a regulatory checkbox, they are a public-facing commitment to clear, honest, and accessible science. Well-prepared lay summaries demonstrate respect for participants, accountability to the public, and alignment with international transparency goals.

Sponsors that prioritize early, accurate, and well-written lay summaries stand out not just for compliance—but for their credibility, ethics, and public impact.