In multicentre clinical trials, no result can be considered reliable if patients do not fully understand what they are being asked. This is the challenge addressed by linguistic validation: a methodological process that ensures a clinical instrument —such as a questionnaire, informed consent form or patient-reported outcome measure— conveys the same meaning across all languages and cultures in which it is used.
Unlike conventional translation, linguistic validation does not simply involve transferring words from one language to another. Its purpose is to achieve conceptual equivalence: ensuring that a patient in Munich, Bogotá or Tokyo interprets a question about severe pain or fatigue in a comparable way, allowing the data collected to be combined and statistically analysed without linguistic bias.
What does the linguistic validation process involve?
The linguistic validation process follows a sequence of standardised steps, aligned with good practice guidelines for the translation and cultural adaptation of patient-reported outcome instruments.
The first stage is the initial translation, carried out independently by two native translators of the target language with clinical expertise. This is followed by reconciliation, where a specialist compares both versions and creates a single harmonised version that incorporates the strengths of each translation. This reconciled version then undergoes back translation —a process in which a linguist who has not seen the original document translates it back into the source language— to identify any potential deviations in meaning from the original text.
The harmonisation stage involves comparing the back translation with the source document and resolving any discrepancies. When required by the study protocol, the process concludes with a cognitive debriefing report: interviews with patients from the target population to verify that they understand and interpret each questionnaire item as intended by the original author.
Why is it critical in a clinical trial?
Regulatory authorities require sponsors of multicentre trials to demonstrate conceptual equivalence between language versions, particularly for instruments measuring patient-reported outcomes. Without linguistic validation, sponsors face three specific risks: non-comparable data between study centres in different countries, regulatory concerns that may delay approval, and, in the worst-case scenario, informed consent forms that participants do not fully understand.
The cost of correcting an instrument after patient recruitment has started is considerably higher than validating it properly during the study design phase. This is why CROs and pharmaceutical companies managing international trials consider linguistic validation a quality requirement rather than an optional step.
The role of a specialised language partner
Successfully carrying out this process requires more than linguistic expertise: it requires medical and scientific linguists who understand the specific terminology used in clinical protocols, informed consent forms, case report forms and clinical outcome assessments.
At Lexic, we have more than 15 years’ experience supporting pharmaceutical companies and CROs with clinical trial and preclinical research translations, applying comprehensive linguistic validation processes in accordance with the quality requirements of UNE-EN ISO 17100:2015.
This work forms part of our broader medical and scientific translation services and is directly linked to the regulatory affairs requirements established by health authorities in each market where a dossier is submitted.
This level of rigour is particularly important in therapeutic areas involving highly subjective symptoms, such as oncology, mental health, chronic diseases and obesity, where quality-of-life questionnaires and patient diaries depend entirely on participants understanding each question exactly as intended by the research team. A subtle mistranslation in just one of these instruments can introduce statistical noise that is difficult to identify and even harder to correct once recruitment has been completed.
If your organisation is designing a multicentre clinical trial and needs to ensure that every patient-reported outcome instrument is conceptually equivalent across all study languages, request a quote and tell us about the scope of your project.
