Plain Language Summaries for Clinical Trials: A Guide

This isn’t a patient-engagement refinement anymore - it’s a submission deadline. Here’s what a plain language summary actually has to do, by when, and in how many languages.

What a Plain Language Summary Actually Is (& isn’t)

A PLS is not a shorter version of the clinical study report, and it isn’t marketing copy either - it’s a distinct document written for a different reader. Where a study report or journal article is written for regulators, clinicians, and researchers, a PLS is written for people who participated in the trial, and the public who might one day consider participating in one. That shift in audience changes almost everything about the document: it has to stay non-promotional, present both positive and negative findings objectively, and use substance names rather than trade names, since a layman reader has no reason to already know the difference without reading the PLS.

The Deadline That Makes This Regulatory, and not Optional

Since EU Clinical Trials Regulation 536/2014 became fully applicable in January 2022, a PLS is a submission requirement, not an optional add-on. Sponsors of EU trials must submit a plain language summary of results to the Clinical Trials Information System (CTIS) within 12 months of a trial’s completion, or within 6 months for pediatric trials, alongside the technical summary. The gap this closes is real-time: one study found only 38% of parents, whose children participated in a pediatric trial had never received a summary of the results, even though 64% said they wanted one - the requirement exists because that gap was the norm, not the exception.

"Reading Level" Is a Requirement, Not a stylistic Preference

EU CTR guidance is specific about the target reading level: most PLS documents are written at a 6th-to-8th-grade US reading level - roughly what a 12-year-old could follow - corresponding to level 2-3 on the International Adult Literacy Survey Scale. That’s a MAJOR constraint, not a suggestion: MedDRA preferred terms and standard adverse-event terminology, both routine in a clinical study report, are exactly the language a PLS has to translate into everyday description without losing clinical accuracy. Getting the reading level right usually means treating this as a rewrite by someone trained in health literacy and plain-language writing, not a shortening exercise performed on the original technical text.

Multilingual translation is the Default, Not the Exception

Most trials that trigger a PLS requirement also ran in more than one country, which means the summary has to be produced in every relevant language, rather than translated once into English and left there. That’s a harder translation problem than it looks: the translated version has to hit the same reading-level target in the destination language (i.e. the target language of the relevant country, which may also include multiple dialects in the same location), not just render the source text accurately - literal, correct translation can still fail the requirement if the result reads at a graduate level (in French or German or any other language) even though the English version was fine. Building the reading-level check into the translation step itself, rather than after it, is usually what separates a PLS that clears review from one that bounces back.

Why Sponsors Get This Wrong - and What a Good Process Looks Like

The most common failure isn’t missing the deadline - it’s submitting a PLS that technically complies but doesn’t actually work for a layman reader, because it was drafted by shortening the clinical study report rather than rebuilding it for a different audience. Sponsor-side review procedures now exist specifically to close that gap, inviting real patient or caregiver groups to review a PLS draft and report anything confusing before submission - treating comprehension, not just the word count, as the thing being tested. A PLS that passes that kind of review also tends to be the one that reads fluently once translated, since clear source text stays clear across languages far more reliably than a detailed text does.