Reflectance Spectrophotometer: The Dermatologists' Sphygmomanometer for Skin Phototyping?

To date, human skin phototype (SPT) has been determined subjectively by self- or trained investigator assessment using sun burning and/or sun tanning responses, ethnicity, hair, and eye color. This study evaluated objective reflectance spectrophotometer (RS) assessment of SPT in 353 males or females (18–72 years old with Fitzpatrick SPT I–VI) using the area-under-the-intensity curve (AUIC) over the 450–615 nm wavelength interval of reflected light (AUIC). Photoprotected constitutive skin color sites produced higher AUIC values than photo-exposed facultative skin color sites. Constitutive skin color at the upper volar arm was equal to the buttocks. Within-site and between-site AUIC reproducibility of constitutive skin color at the upper volar arm was 3 and 5% coefficient of variation (CV), respectively, which was similar to seasonal variability (8% CV). AUIC values decreased proportionately at both constitutive and facultative sites as a function of increasing SPT from I to VI (r=0.8). RS-measured constitutive skin color at the upper volar arm fit a quadratic equation (r2=0.94) that differentiated (P<0.05) between each of the six SPTs and agreed ±1 SPT category with clinician-assessed SPT. Thus, RS assessment of constitutive skin color at the upper volar arm provides a quick, noninvasive, precise, and accurate method to objectively determine SPT.