Development and Validation of a Photonumeric Scale to Assess Marionette Lines.

Background: A validated scale is needed for objective and reproducible comparisons of marionette lines before and after treatment in clinical studies.

Objective: To describe the development and validation of a 5-point photonumeric marionette lines scale.

Methods: The scale was developed to include an assessment guide, verbal descriptors, and real and morphed subject images for each scale grade. Intrarater and interrater reliability was evaluated in initial scale validation (web-based review) ( N = 51 ) and live-subject validation ( N = 75 ) studies, each completed during 2 sessions.

Results: In the initial scale validation study, intrarater agreement for 2 physician raters was near perfect (weighted kappa = 0.92 and 0.94). Interrater agreement was excellent during sessions 1 and 2 (intraclass correlation coefficients of 0.94 and 0.95, respectively). In the live-subject validation study, intrarater agreement for 3 physician raters showed a strong correlation (mean weighted kappa = 0.77). Interrater agreement was high during live-subject validation sessions 1 and 2 (intraclass correlation coefficients = 0.89 for both sessions).

Conclusion: This new marionette lines scale is a validated and reliable scale for physician rating of marionette line severity.