Examples
Worked examples
- Is an instance
A sponsor posts a two-to-three page lay summary to CTIS 11 months after a Phase 3 trial's global end date, written in the language(s) of each EU/EEA member state where the trial ran, stating in plain terms how many participants took part, what was compared, what the trial found, and what happens next — alongside, not instead of, the technical results summary required under the same CTR results-reporting obligation.
- Is an instance
A paediatric trial sponsor submits its lay summary within the shortened 6-month post-trial-end window that applies specifically to paediatric studies under the CTR framework, rather than the general 12-month deadline that applies to adult trials.
Counter-examples
Looks similar, but isn't
- Not an instance
A condensed version of the scientific abstract that keeps technical terminology (e.g. unexplained statistical or pharmacological jargon) intact is not a plain language summary in the operational sense — the defining feature is accessibility to a non-specialist reader, not brevity alone.
- Not an instance
A general-purpose lay summary written for a funder's public-facing grant database (for example, the plain-English project summaries UKRI or Horizon Europe request at the application stage) is a related but distinct artifact — it summarises a funded project or paper for a public audience, but is not the CTR Article-mandated, CTIS-submitted results PLS that this term specifically describes.
Editorial commentary
Why the Plain Language Summary Requirement Exists
Clinical trial participants and the wider public fund and enable clinical research — as taxpayers, as patients, and often directly as trial volunteers — yet trial results have historically been published, if at all, in journal articles and regulatory documents written for specialists. The EU Clinical Trials Regulation’s lay-summary requirement is part of a broader research-transparency shift that treats returning results to participants and the public, in a form they can actually understand, as a core obligation of running a trial, not an optional communications extra. The same logic underpins related transparency obligations covered elsewhere on this site, including trial registration and full results disclosure.
Regulatory Basis: EU CTR 536/2014 and CTIS
Regulation (EU) No 536/2014 entered into application on 31 January 2022, replacing the earlier Clinical Trials Directive 2001/20/EC, and established the Clinical Trials Information System (CTIS) as the single EU/EEA portal for trial authorisation, conduct oversight, and results reporting. Results reporting under the CTR includes both a technical summary of results and a separate lay summary, submitted to CTIS as part of the same results-disclosure obligation. Reported submission windows are generally 12 months after a trial’s global end date for standard adult trials, extended up to 30 months for certain non-therapeutic Phase 1 studies, and shortened to 6 months for paediatric trials — sponsors should confirm current figures against CTIS guidance and the Regulation’s implementing provisions before relying on them for a specific submission, since annex-level detail is periodically revised by delegated act.
What a PLS Must Cover
Guidance from the European Commission and national competent authorities converges on a common structure: the trial’s objective and background in accessible terms, who took part (numbers and, where relevant, key eligibility criteria), what was done (in outline, without requiring the reader to understand the underlying methodology), what was found (including whether the trial met its objectives), relevant safety information, and where a reader can find more information. It should be written for a genuinely lay reading level — avoiding statistical and pharmacological jargon rather than simply shortening it — and produced in the language(s) of the member state(s) where the trial was conducted, not only in English.
Plain Language Summary vs. Scientific Abstract
A PLS is not a shorter version of a paper’s or trial report’s scientific abstract. The two serve different readers and different purposes: a scientific abstract assumes disciplinary background knowledge and technical vocabulary, while a PLS assumes neither, and is written to be understood by a trial participant or member of the public with no scientific training. This site’s separate guide on writing plain-language summaries for research papers covers the broader funder-facing version of this practice (for example UKRI, NIHR, and Horizon Europe application and reporting requirements); this term specifically describes the CTR/CTIS-mandated results PLS for a registered clinical trial, which is a distinct, legally-required deliverable rather than a funder best-practice expectation.
PLS Within the Wider Transparency Framework
The plain language summary requirement sits alongside, and depends on, other clinical trial transparency mechanisms: a trial must first be registered before results (technical and lay) can be meaningfully reported against it, and both registration and lay-summary reporting are components of the broader clinical trial transparency obligations that EU-regulated sponsors operate under. Producing a PLS is also downstream of good trial conduct more broadly — accurate, complete results reporting depends on the same conduct and documentation standards set out in ICH Good Clinical Practice (GCP), since a lay summary can only be as accurate as the underlying trial record it summarises.
Beyond the EU: Best Practice Where Not Mandated
Outside the jurisdictions where a PLS is a binding submission requirement, many funders, journals, and research institutions now request or expect one as a matter of research-transparency best practice — reflecting the same participant- and public-facing accountability rationale as the CTR requirement, even where no equivalent legal deadline applies. Sponsors running multi-region trials increasingly produce a PLS as standard practice across all sites rather than only where strictly mandated, both to meet participant expectations and to prepare for jurisdictions where the requirement may be extended in future.
Related Terms
See also: Clinical Trial Transparency, Clinical Trial Registration, ICH GCP (Good Clinical Practice), and the guide on writing plain-language summaries for research papers.
Machine-readable encodings
Use in your systems
<role vocab="credit"
vocab-identifier="https://casrai.org/dictionary/"
vocab-term="Plain Language Summary (PLS)"
vocab-term-identifier="https://casrai.org/dictionary/term/plain-language-summary" />{
"@context": "https://schema.org",
"@type": "DefinedTerm",
"@id": "https://casrai.org/dictionary/term/plain-language-summary",
"name": "Plain Language Summary (PLS)",
"identifier": "https://casrai.org/dictionary/term/plain-language-summary",
"description": "<p>A <strong>plain language summary (PLS)</strong> is a short, jargon-free account of a clinical trial's design and results, written so that a layperson — typically framed as a trial participant or member of the public — can understand what the study tested, what it found, and what that means, without needing scientific or medical training. In EU-regulated clinical trials it is a defined regulatory deliverable, not an optional courtesy: under <a href='https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32014R0536' target='_blank' rel='noopener'>Regulation (EU) No 536/2014</a> (the EU Clinical Trials Regulation, CTR), sponsors of trials authorised under the Regulation must submit a lay summary of the trial's results to the Clinical Trials Information System (CTIS) alongside the technical results summary, generally within 12 months of the trial's global end date. That deadline extends to up to 30 months for certain non-therapeutic Phase 1 trials, and shortens to 6 months for paediatric trials. Lay summaries must generally be provided in the official language(s) of the EU/EEA member state(s) where the trial was conducted, not only in English.</p><p>An instance of a PLS is a written summary that (a) covers the trial's purpose, participant population, methods, and results including any relevant safety information, (b) is written for a non-specialist reading level (commonly targeted around a 12-14 year-old reading age in EMA/national guidance), and (c) is submitted as a distinct, identifiable document alongside — not merged into — the technical/scientific summary of results. A document that simply restates the scientific abstract in shorter form, or that omits the trial's actual findings in favour of only describing its design, does not meet the operational bar even if labelled a lay summary.</p>",
"inDefinedTermSet": "https://casrai.org/dictionary/domain/clinical-research#set",
"url": "https://casrai.org/dictionary/term/plain-language-summary",
"sameAs": [],
"license": "https://creativecommons.org/licenses/by/4.0/",
"publisher": {
"@id": "https://casrai.org/#organization"
},
"dateModified": "2026-07-23T09:41:50",
"inLanguage": "en"
}
