Literature Searches
A dermatologist and a physician/scientist performed literature searches on September 10, 2020, on PubMed and Google Scholar as a secondary source. The review was limited to the English language literature published through September 2020 and used search terms pertaining to racial/ethnic differences in stratum corneum (SC) properties and skincare considerations. Included were original research, clinical guidelines, algorithms, relevant reviews, and evidence-based recommendations describing the current practice. Further excluded were publications that did not specifically address the SC barrier in skin of color, articles covering skincare in specific dermatological conditions, and publications in languages other than English.
Role of the Panel
Selected information from the literature searches, coupled with the panel's opinion and experience, was used to adopt statements and recommendations.
The results of the literature searches were integrated into summary statements, presented, and discussed during a virtual meeting on October 10, 2020. The online conference replaced a face-to-face meeting that was canceled due to COVID-19. In a workshop, advisors divided into two groups to create a final set of summary statements about racial/ethnic differences in SC barrier structure and function and skincare for this population, working with 19 draft messages. The final six statements integrate the combined output from the workshop groups and post-meeting online reviews from individual advisors.
A dermatologist and a physician/scientist performed literature searches on September 10, 2020, on PubMed and Google Scholar as a secondary source. The review was limited to the English language literature published through September 2020 and used search terms pertaining to racial/ethnic differences in stratum corneum (SC) properties and skincare considerations. Included were original research, clinical guidelines, algorithms, relevant reviews, and evidence-based recommendations describing the current practice. Further excluded were publications that did not specifically address the SC barrier in skin of color, articles covering skincare in specific dermatological conditions, and publications in languages other than English.
Role of the Panel
Selected information from the literature searches, coupled with the panel's opinion and experience, was used to adopt statements and recommendations.
The results of the literature searches were integrated into summary statements, presented, and discussed during a virtual meeting on October 10, 2020. The online conference replaced a face-to-face meeting that was canceled due to COVID-19. In a workshop, advisors divided into two groups to create a final set of summary statements about racial/ethnic differences in SC barrier structure and function and skincare for this population, working with 19 draft messages. The final six statements integrate the combined output from the workshop groups and post-meeting online reviews from individual advisors.
RESULTS
Based on a review of the literature and a modified Delphi process, the expert panel developed the below six consensus statements. A summary of relevant data and expert opinion for each statement is included.
1. Attributes contributing to skin hydration, roughness, and other properties can be grouped into genetic (gender, race, ethnicity), environmental (lifestyle, BMI, geography), and individual factors.
Stratum Corneum Thickness/Desquamation
Several studies have investigated SC differences between Black and White skin. While SC thickness between Black and White individuals has been found to be comparable.2-8 Black skin has been reported to have a greater number of cell layers that are arranged more compactly.7,9 Increased cell layers may indicate a stronger SC barrier and faster recovery from barrier damage. White subjects have intermediate barrier strength as evidenced by tape strippings, and Asians have been demonstrated to require the least number of tape "strippings" to disrupt the SC barrier. This finding indicates a weaker barrier strength and slower recovery from barrier damage in the Asian population that supports the observation of sensitive skin seen in Asians.9
In one study, corneocyte surface area on the upper-outer arm was similar in Black, White, and Asian subjects, while Black subjects were found to have increased spontaneous desquamation compared to White and Asian subjects.10
The increased desquamation seen in this study may explain, at least in part, the observed tendency for xerosis in Black skin. However, in another study, the desquamation index was higher in facial skin (cheeks and forehead) of White subjects compared to Black subjects, whereas dryness scores were higher on the legs of Black subjects compared to White subjects.11 Another study evaluating the amount of active SCCE enzyme on SC tape strips as a marker of desquamation on ventral forearm samples found evidence for slower desquamation in Black subjects than White and East Asian subjects. In contrast, a different study reported no difference in skin roughness and scaliness between
1. Attributes contributing to skin hydration, roughness, and other properties can be grouped into genetic (gender, race, ethnicity), environmental (lifestyle, BMI, geography), and individual factors.
Stratum Corneum Thickness/Desquamation
Several studies have investigated SC differences between Black and White skin. While SC thickness between Black and White individuals has been found to be comparable.2-8 Black skin has been reported to have a greater number of cell layers that are arranged more compactly.7,9 Increased cell layers may indicate a stronger SC barrier and faster recovery from barrier damage. White subjects have intermediate barrier strength as evidenced by tape strippings, and Asians have been demonstrated to require the least number of tape "strippings" to disrupt the SC barrier. This finding indicates a weaker barrier strength and slower recovery from barrier damage in the Asian population that supports the observation of sensitive skin seen in Asians.9
In one study, corneocyte surface area on the upper-outer arm was similar in Black, White, and Asian subjects, while Black subjects were found to have increased spontaneous desquamation compared to White and Asian subjects.10
The increased desquamation seen in this study may explain, at least in part, the observed tendency for xerosis in Black skin. However, in another study, the desquamation index was higher in facial skin (cheeks and forehead) of White subjects compared to Black subjects, whereas dryness scores were higher on the legs of Black subjects compared to White subjects.11 Another study evaluating the amount of active SCCE enzyme on SC tape strips as a marker of desquamation on ventral forearm samples found evidence for slower desquamation in Black subjects than White and East Asian subjects. In contrast, a different study reported no difference in skin roughness and scaliness between
