Validation of a Chin Retrusion Scale for Chinese Subjects

Chin augmentation procedures are gaining in popularity. The purpose of this study was to validate the China (Allergan) Chin Retrusion Scale (CACRS) and to evaluate the reliability of the scale. A team of 10 physicians based in Beijing, China, consisting of 1 principal investigator and 9 independent raters, assessed a pool of subject images. Using standardized equipment to capture 2-dimensional images, 100 subjects were photographed from a left, lateral, 90° view. Two measures were used to assess the validity of the scale: rater evaluations of clinically significant differences in 52 pairs of images and rater assessment of chin retrusion using the CACRS to grade the 100 images. The CACRS demonstrated almost perfect inter-rater agreement during 2 validation sessions, with intraclass correlation coefficients of 0.89 and 0.90 at sessions 1 and 2, respectively. Overall inter-rater agreement for all 9 raters was almost perfect, with a weighted kappa of 0.82. Based on inter- and intra-rater agreement, the CACRS was validated for physician ratings of chin retrusion in Chinese subjects. Results from clinical significance evaluations indicated that a 1-grade difference between image pairs was considered clinically meaningful for the CACRS. The CACRS is a validated and reliable photonumeric scale for the assessment of chin retrusion in Chinese men and women. The scale is a clinically significant reference tool for evaluating the effect of chin augmentation.