Novel Validated Five-point Photonumeric Scales for Assessment of Static and Dynamic Forehead Lines

Background: The objective of this investigation was to create and validate five-point photonumeric scales which assess static and dynamic forehead lines. Methods: Two different novel five-point photonumeric scales for the assessment of static and dynamic forehead lines were developed. Moreover, a photoguide was created, including subjects from both sexes, all age groups, and different Fitzpatrick skin types. A total of 11 raters from all over the world were involved in the digital validation, whereas four raters performed a live validation. Results: The Croma Static Forehead Lines-Assessment Scale showed almost perfect inter and intra-rater agreement in both the digital and the live setting with inter-rater intraclass correlation coefficients of 0.86 [95% confidence interval (CI): 0.82-0.89] in the first digital rating and 0.82 [95% CI: 0.78-0.86] in the second digital rating. The Croma Dynamic Forehead Lines-Assessment Scale showed almost perfect inter and intra-rater agreement in the digital setting with inter-rater intraclass correlation coefficients of 0.83 [95% CI: 0.79-0.86] in the first digital rating and 0.80 [95% CI: 0.75-0.84] in the second rating and almost substantial agreement in the live setting. Conclusions: The Croma Static Forehead Lines-Assessment Scale and the Croma Dynamic Forehead Lines-Assessment Scale have excellent inter and intra-rater agreements to be justifiably used in the clinical and study setting, both digitally and live across ethnic groups.