Development and Validation of a Photonumeric Scale for Assessment of Chin Retrusion

BACKGROUND A validated scale is needed for objective and reproducible comparisons of chin appearance before and after chin augmentation in practice and clinical studies. OBJECTIVE To describe the development and validation of the 5-point photonumeric Allergan Chin Retrusion Scale. METHODS The Allergan Chin Retrusion Scale was developed to include an assessment guide, verbal descriptors, morphed images, and real subject images for each scale grade. The clinical significance of a 1-point score difference was evaluated in a review of multiple image pairs representing varying differences in severity. Interrater and intrarater reliability was evaluated in a live-subject validation study (N = 298) completed during 2 sessions occurring 3 weeks apart. RESULTS A difference of ≥1 point on the scale was shown to reflect a clinically meaningful difference (mean [95% confidence interval] absolute score difference, 1.07 [0.94-1.20] for clinically different image pairs and 0.51 [0.39-0.63] for not clinically different pairs). Intrarater agreement between the 2 live-subject validation sessions was substantial (mean weighted kappa = 0.79). Interrater agreement was substantial during the second rating session (0.68, primary end point). CONCLUSION The Allergan Chin Retrusion Scale is a validated and reliable scale for physician rating of severity of chin retrusion.