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Development and Validation of a Photonumeric Scale for Assessment of Chin Retrusion
Jonathan M Sykes1, Alastair Carruthers, Bhushan Hardas
1*Department of Otolaryngology/Facial Plastic Surgery, UC Davis Medical Group, Sacramento, California; †Department of Dermatology and Skin Science, University of British Columbia, Vancouver, British Columbia, Canada; ‡Allergan plc, Irvine, California; §Division of Dermatology, University of California at Los Angeles, Los Angeles, California; ‖Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada; ¶Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut; #Peloton Advantage, LLC, Parsippany, New Jersey.
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.
