Minimally Important Difference of the FACE-Q Skin Cancer Module: A Distribution-Based and Anchor-Based Analysis

BackgroundThe FACE-Q Skin Cancer Module is a validated patient-reported outcome measure for facial skin cancer surgery. However, the minimally important difference (MID)-- the smallest change in score perceived as meaningful by patients--has not been established. Without the MID, individual score changes cannot be interpreted clinically. This study aimed to determine the MID for all four FACE-Q Skin Cancer scales. MethodsProspective cohort study at a tertiary center (2017-2018). Patients completed the FACE-Q preoperatively and at 1 week, 3 months, and 1 year postoperatively. MID was estimated using distribution-based methods (0.5 standard deviation, standard error of measurement) and an anchor-based approach using the FACE-Q Adverse Effects scale as an implicit anchor. Internal consistency (Cronbachs ), effect sizes, and standardized response means were calculated. ResultsOf 287 enrolled patients, 111 had paired baseline-three-month data. All scales had strong internal consistency ( = 0.82-0.93). Cancer worry showed the largest improvement from baseline to three months (mean change -3.1 {+/-} 5.8; SRM = -0.54; p < 0.001). When we combined the estimates, the MID values (sum scores / 0-100 scale) were: Appearance Satisfaction 2.0 / 5.6, Psychosocial Distress 2.0 / 6.2, Cancer Worry 2.5 / 6.2, and Scar Satisfaction 2.0 / 6.2. Anchor-based estimates for the Scar scale (2.4 sum points) confirmed distribution-based findings. ConclusionsThis study establishes the first MID values for the FACE-Q Skin Cancer Module. A change of approximately 2-2.5 sum points (5-6 points on a 0-100 scale) represents a minimally important difference across all scales. These thresholds enable clinicians and researchers to interpret individual FACE-Q score changes and design adequately powered clinical trials.