Self–reported skin colour and erythemal sensitivity vs. objectively measured constitutive skin colour in an African population with predominantly dark skin

Abstract

Background Skin colour is an important factor in skin-related diseases. Accurate determination of skin colour is important for disease prevention and supporting healthy sun behaviour, yet such data are lacking for dark skin types. Methods Self-perceived, natural skin colour and sun – skin reaction were compared with objectively measured skin colour among an African population with predominantly dark skin. Unexposed skin of 556 adults (70.1% Black) was measured with a reflectance pectrophotometer to calculate an individual typology angle (°ITA). Participants reported self-perceived skin colour and erythemal sensitivity. Results There was a strong, positive monotonic correlation between self-reported and measured skin colour (Spearman q=0.6438, P<0.001), but only a weak correlation between self-reported erythemal sensitivity and measured skin colour (Spearman q = 0.2713, P<0.001). Self-report biases in underestimation and overestimation of skin colour were evident. Many participants with ‘dark brown’ and ‘black’ skin had difficulty in classifying erythemal sensitivity. Conclusions In Africa, self-reported skin colour could poentially be used in lieu of spectrophotometer measurements, but options for questions on sunburn and tanning require suitable adjustment. Our study provides evidence of range in °ITA values among residents in Africa and reinforces previous results that self-report may be reliable for determining skin colour, but not erythemal sensitivity, for dark skin individuals.