Cross-Cultural Adaptation of the Oral Frailty Index-8 for United States English-Speakers

Objective: Oral frailty, the age-related decline in oral and pharyngeal function, is associated with physical frailty, sarcopenia, and cognitive decline. The Oral Frailty Index-8 (OFI-8) is a patient-reported outcome measure developed in Japan to assess oral frailty risk. This study aimed to culturally and linguistically adapt the OFI-8 for English-speaking older adults in the United States. Study Design: Cross-cultural and cross-linguistic adaptation of the OFI-8 by an expert committee, followed by administration of the adapted OFI-8 and structured cognitive interviews with 22 English-speaking adults aged 65 years and older. Setting: Outpatient tertiary academic voice and swallowing center in New York City. Methods: Following the Professional Society for Health Economics and Outcomes Research (ISPOR) guidelines, the OFI-8 underwent forward translation, back translation, expert committee review, and reconciliation. Cognitive interviews were then conducted with 22 participants aged 65 years and older. A think-aloud and verbal-probing approach was used to evaluate comprehension, clarity, and cultural appropriateness. Interviews were transcribed and analyzed using thematic analysis. Results: Several cultural adaptations were made, including replacing Japanese food examples with US-familiar foods of similar texture. Three questionnaire items and the instructions were refined following participant feedback to improve syntactic flow, clarity, and understanding. The final US-English version maintained conceptual equivalence of the original OFI-8 while adapting language and examples for US cultural relevance. Conclusion: A culturally adapted US-English version of the OFI-8 was developed through structured translation, expert review, and cognitive interviews. Further validation studies are necessary to establish its clinimetric properties and support clinical application for early detection of oral frailty in US older adults.