Cultural adaptation: translatability assessment and linguistic validation of the patient-reported outcome instrument for irritable bowel syndrome with diarrhea

BACKGROUND AND OBJECTIVE Following a 2009 US Food and Drug Administration guidance, a new patient-reported outcome (PRO) instrument was developed to support end points in multinational clinical trials assessing irritable bowel syndrome with diarrhea (IBS-D) symptom severity. Our objective was to assess the translatability of the IBS-D PRO instrument into ten languages, and subsequently perform a cultural adaptation/linguistic validation of the questionnaire into Japanese and US Spanish. MATERIALS AND METHODS Translatability assessments of the US English version of the IBS-D PRO were performed by experienced PRO translators who were native speakers of each target language and currently residing in target-language countries. Languages were Chinese (People's Republic of China), Dutch (the Netherlands), French (Belgium), German (Germany), Japanese (Japan), Polish (Poland), Portuguese (Brazil), Russian (Russia), Spanish (Mexico), and Spanish (US). The project team assessed the instrument to identify potential linguistic and/or cultural adaptation issues. After the issues identified were resolved, the instrument was translated into Spanish (US) and Japanese through a process of two forward translations, one reconciled translation, and one backward translation. The project team reviewed the translated versions before the instruments were evaluated by cognitive debriefing interviews with samples of five Spanish (US) and five Japanese IBS-D patients. RESULTS Linguistic and cultural adaptation concerns identified during the translatability assessment required minor revisions, mainly the presentation of dates/times and word structure. During the cognitive debriefing interviews, two of five Spanish respondents misunderstood the term "bowel movement" to mean only diarrhea in the Spanish version. Consequently, the term was changed from "movimiento intestinal" to "evacuaciones". None of the Japanese respondents identified issues with the Japanese version. CONCLUSION The translatability of the IBS-D PRO instrument into ten target languages was confirmed, with only minor changes made to the translations of the instrument. The translation and linguistic validation into Spanish (US) and Japanese provide evidence that this instrument can be used in multinational trials and clinical settings.