Development and Validation of Two skin Quality Photonumeric Scales Assessing Skin Smoothness and Cheek Lines

Skin smoothness and cheek lines are key indicators of skin quality targeted by aesthetic treatments and surgery to improve perceived youthfulness and confidence. Validated photonumeric scales provide a standardized, reliable, and reproducible grading of skin quality.

To develop and validate two Canfield skin quality photonumeric scales assessing skin smoothness and cheek lines.

Two 5-level photonumeric scales for skin smoothness and cheek lines were developed. Validation consisted of three exercises: live validation, clinical relevance, and photographic validation. Five certified clinicians completing the grading in two sessions, two weeks apart and agreement was measured using Cicchetti-Allison kappa. Sixty-eight and 72 participants, respectively, attended validation for skin smoothness and cheek lines. Clinical relevance was evaluated by comparing ratings of 90 image pairs evaluated as clinically different and not clinically different. Photographic validation was completed as per live validation on the standardized images used for clinical relevance.

For both scales, the live and photographic validation demonstrated almost perfect levels of intra-rater reliability (combined Kappas > 0.801) and substantial to almost-perfect inter-rater reliability (median pairwise Kappas > 0.728), across a diverse population. Clinical relevance showed a meaningful 1-point difference in pairs that are not clinically different and images with 1-point difference (p<0.001).

The Canfield Skin Quality Scale - Skin Smoothness and the Canfield Skin Quality Scale - Cheek Lines are robust and reproducible outcome measures for use live and on images, supporting their use in clinical studies and practice across diverse populations.