Validating a Series of Photonumeric Rating Scales for Use in Facial Aesthetics Using Statistical Analysis of Intra- and Inter-rater Reliability

Abstract

Background Growing demand for minimally invasive aesthetic procedures to correct age-related facial changes and optimize facial proportions has been met with innovation, but has created an unmet need for objective assessment tools to evaluate results empirically. Objectives The purpose of this study is to establish the intra- and inter-rater reliability of ordinal, photonumeric, 4- or 5-point rating scales for clinical use to assess facial aesthetics. Methods Board-certified plastic surgeons and dermatologists (3 raters) performed live validation of jawline contour, temple volume, chin retrusion, nasolabial folds, vertical perioral lip lines, midface volume loss, lip fullness, and crow’s feet dynamic- and at rest- rating scales over 2 rounds, 2 weeks apart. Subjects selected for live validation represented the range of scores and included 54-83 subjects for each scale. Test-retest reliability was quantitated through intra- and inter-rater reliability, determined from the mean weighted kappa and Round 2 Intraclass Correlation Coefficients (ICC), respectively. The clinical significance of a one grade difference was assessed through rater comparison of 31 pairs of side-by-side photographs of subjects with the same grade or a different grade on the developed scales. Results The study demonstrated substantial to near-perfect intra-rater and inter-rater reliability of all scales when utilized by trained raters to assess a diverse group of live subjects. Furthermore, the clinical significance of a 1-point difference on all the developed scales was established. Conclusions The high test-retest reliability and intuitive layout of these scales provide an objective approach with standardized ratings for clinical assessment of various facial features.