Effect of Age, Gender, and Sun Exposure on Ethnic Skin Photoaging: Evidence Gathered Using a New Photonumeric Scale.

Background: African-Americans are less affected by photoaging than lighter skin individuals. Although scales for photoaging have been developed for Caucasians and Asians, no scale exists for African-Americans.

Aim: To develop a photonumeric scale for photoaging and to determine factors that contribute to photoaging in African-Americans.

Methods: Five participants' photographs were selected as standards to create a 9-point photonumeric scale (0 = none, 8 = most severe). Three blinded dermatologists used the scale to grade the remaining participants' photographs.

Results: Interrater reliabilities were 0.775 (95% CI: 0.635, 0.880) for trial 1 and 0.832 (0.747, 0.883) for trial 2. Intrarater reliabilities, assessed over a 1 week interval, were 0.863 (0.727, 0.940), 0.928 (0.890, 0.954), and 0.866 (0.739, 0.935) for the three graders, indicating strong agreement. Photoaging scores were then correlated with participants' survey on lifestyle factors, which yielded age as a significant predictor (r = 0.91, p < 0.001). Furthermore, multiple regression model to predict facial photoaging (adjusted R = 0.849) selected age (b = 0.111, p < 0.001), sun exposure (b = 0.206, p = 0.014), and gender (b = -0.388, p = 0.063) as the most important variables.

Conclusions: A reliable photonumeric scale for photoaging in African Americans was developed. Age, sun exposure, and male gender were found to be contributory factors to photoaging.