Validation of digital photographic reference scales for evaluating facial aging signs

Abstract

Background

Validated tools are essential to evaluate facial skin aging for both dermatological and cosmetic investigations. While many visual aging scales have been developed, few have been validated and none in terms of degree of distinguishability (DD). We developed and validated a series of visual scales using a novel digital interface for scoring facial skin aging in Caucasian women.

Materials and methods

Three dermatologists independently established scales for 12 distinct aging signs from high-definition facial photographs of 400 adult women (Fitzpatrick phototypes I-IV) taken under standardized conditions. They then selected a consensus scale for each individual sign with a representative photo per grade. Scales were integrated into a digital interface allowing simultaneous viewing of all grades of each scale alongside the photograph of a test subject. Next, scales were validated by a different dermatologist, a general practitioner and a non-medical expert skin evaluator using photos of 350 women which had not been used for establishing the scales.

Results

Kappa estimates showed almost perfect agreement for wrinkle and skin aging scales (≥0.85) and moderate to substantial agreement for scales relating to color irregularities (telangiectasia, solar lentigines, freckles) for both inter- and intra-observer reproducibility. Intra-observer DD estimates were mostly high. Non-dermatologists performed well on reproducibility for both Kappa (from 0.6 to 0.9) and DD estimates.

Conclusion

Our work demonstrates that the digital interface scales for 12 distinct aging features are highly suitable for use in clinical and epidemiological studies on skin aging by both dermatologists and non-dermatologists.