Skin Age Index: Development of a Convenient and Quantitative Indicator of Facial Skin Aging and Its Application to Evaluation of the Efficacy of Three Anti-Aging Skin Care Products Containing GFF (Pitera)

Abstract

Background Facial appearance is regarded as a typical index of aging. However, people of the same age do not necessarily show the same aging in terms of their facial appearance. There is thus a need for an easy-to-understand indicator representing visible facial skin aging in comparison with that of individuals of a similar age. Objectives The purpose of this study was to develop a simple and accurate index of skin to understand the degree of facial skin aging. Methods Facial skin images were taken with two simple and convenient facial imaging devices (Magic Scan, Magic Ring) in 110 Asian women aged 20 - 60 years, and texture, pores, wrinkles, and dullness (skin unevenness) were quantified as parameters of visual skin aging. Regression analysis was performed on each skin aging parameter and age, and the variation of change in skin aging parameters over time for each subject was calculated. The ratio of each measured skin aging parameter to the mean variation of that same parameter among individuals of the same age as the subject and that ratio was converted into a delta (Δ) age value. Skin age for each skin aging parameter was then calculated by adding or subtracting the Δ skin age to the subject’s chronological age. The average skin age for all four parameters was defined as the overall facial skin age (Skin Age Index). The Skin Age Index was then compared to the results of visual grading of facial skin aging. We also determined the correlation between Skin Age Indexes determined using Magic Scan or Magic Ring. Furthermore, Galactomyces Ferment Filtrate (GFF, Pitera) containing anti-aging skin care products’ treatment efficacy was performed on 21 healthy Asian women to determine the change in skin age. Results Determined Skin Age Index, together with all visible skin aging parameters of texture, pores, wrinkles, and dullness, were highly correlated with actual age. Notably, a high correlation was also observed between visually evaluated comprehensive facial skin aging and Skin Age Index (r = 0.6801 with Magic Scan, r = 0.5668 with Magic Ring). This showed that the degree of skin aging and the apparent skin aging were approximate. The Skin Age Indexes obtained using the two different facial skin imaging devices showed a high correlation (r = 0.8295), suggesting the possibility of calibrating skin age using different image measurement devices. The three GFF-formulated anti-aging skin care products achieved improvements in texture, pores, and wrinkles, and resulted in a skin age that was 5.92 years younger after 1 week of treatment. Conclusions From this study, a method for measuring facial skin age was developed. This Skin Age Index showed an excellent correlation with the subjectively evaluated visible facial skin aging. Furthermore, this Skin Age Index has been shown to be a useful indicator of the effectiveness of applying anti-aging skin care products.