Interpreting Quality-of-Life Questionnaires in Patients with Long-Standing Facial Palsy
Tessa E. Bruins, Martinus M. van Veen, Ingrid J. Kleiss, Dieuwke C. Broekstra, Pieter U. Dijkstra, Koen Ingels, Paul M. N. Werker
Abstract
Objective(s): To interpret change in quality-of-life scores in facial palsy patients by calculating the smallest detectable change (SDC) and minimal important change (MIC) for the Facial Disability Index (FDI), Facial Clinimetric Evaluation (FaCE) scale, and Synkinesis Assessment Questionnaire (SAQ). Materials and Methods: The SDC, for individuals and groups, was calculated using previously collected test–retest data (2-week interval). The MIC (predictive modeling method) was calculated in a second similar facial palsy population using two measurements (1–1.5-year interval) and an anchor question assessing perceived change. Results: SDC individual of FaCE was 17.6 and SAQ was 28.2. SDC group of FaCE was 2.9 and SAQ was 4.6 ( n = 62). Baseline FaCE and SAQ scores were 43.3 (interquartile range [IQR]: 35.8;55.0) and 51.1 (IQR: 32.2;60.0), respectively. MIC for important improvement of FDI physical/social function, FaCE total, and SAQ total were 4.4, 0.4, 0.7, and 2.8, respectively ( n = 88). MIC for deterioration was 8.2, −1.8, −8.5, and 0.6, respectively. Baseline scores were 70.0 (IQR: 60.0;80.0), 76.0 (68.0;88.0), 55.0 (IQR: 40.0;61.7), and 26.7 (IQR: 22.2;35.6), respectively. Number of participants reporting important change for the different questionnaires ranged from 3 to 23 per subscale. Conclusion: Interpreting change scores of the FDI, FaCE, and SAQ is appropriate for groups, but for individual patients it is limited by a substantial SDC.