Psychometric properties of the Facial Disability Index in patients with facial palsy: a systematic review and meta-analysis

Purpose: The aim of the study was to present the systematic review and meta-analysis of the psychometrical analysis of Facial Disability Index (FDI) studies. Methods: A literature search was conducted in the relevant electronic databases “PubMed, Scopus, Web of Science (WoS), and Cochrane Library.” A total of 621 articles were obtained by searching the relevant keywords (PubMed: 384, Cochrane Library: 14, Web of Science: 132, Scopus: 91). A total of 8 papers were included. The four-point classification and rating-based “COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN)” tools were used to evaluate the bias risk and evidence levels. Results: Cronbach’s alpha pooling of FDI total score was (ES): 0.803 (95% CI: 0.73–0.86). Heterogeneity for the Facial Disability Index-Physical Function (FDI-PF) and Facial Disability Index-Social Function (FDI-SF) subscore based on intraclass correlation coefficient (ICC) were I2 = 84.2% (ICC: 0.88, 95% CI: 0.81–0.92) and I2 = 73.7% (ICC: 0.87, 95% CI: 0.81–0.90), respectively. Correlational results between Sunnybrook Facial Grading System (SFGS) with FDI-PF and FDI-SF were 0.38 and 0.22, respectively. The correlations of FDI-PF with Short Form-12 Physical Component Summary (SF-12-PCS) and Short Form-12 Mental Health Component Summary (SF-12-MCS) were 0.43 and 0.28, respectively. Correlation results of FDI-SF with SF-12-PCS and SF-12-MCS were 0.23 and 0.57. The relationship results of Facial Clinimetric Evaluation with FDI-PF and FDI-SF were 0.71 and 0.57, respectively. Conclusion: FDI is a psychometrically valuable questionnaire, especially for the internal consistency, reliability, and validity. In clinical practice, the use of FDI would be valuable, in addition to clinician-based grading, to see more of patients’ social influences precisely.