The reliability and validity of the Turkish version of the Facial Disability Index

Purpose: To translate and cross-culturally adapt the Turkish version of the Facial Disability Index (FDI) and evaluate its psychometric properties, including reliability and validity. Methods: Translation of the original FDI was followed by international guidelines. Paralysis classification was evaluated with House-Brackman Rating System (HBGS). Patients completed Short Form-36 (SF-36) along with the Turkish version of the FDI and refilled the Turkish FDI one week later. Internal consistency and test-retest reliability were analyzed using Cronbach's alpha coefficient and intraclass correlation coefficient (ICC), respectively. Construct validity was assessed by calculating the Spearman's correlation coefficient. Also, exploratory factor analysis was carried out by identifying the factor structure of the scale. Results: After the pre-test of the Turkish FDI, there was no need for linguistic and cultural adaptation. The internal consistency of the physical function subscale was high (0.82). The social/well-being subscale's Cronbach alpha (0.63) was within the acceptable range. Test-retest reliability was excellent (ICC of physical function = 0.91 and social/well-being = 0.93, p < 0.05). The physical function subscale was correlated with the PF subscale of SF-36 and HBGS (r = -0.837 and 0.292, respectively; p < 0.05). Besides, the social/well-being function subscale was correlated with HBGS and all subscales of SF-36, except RP (p < 0.05). Factor analysis results of the Turkish FDI were similar to the other version studies. Conclusion: The Turkish version of the FDI is a valid and reliable questionnaire in patients with peripheral facial paralysis.