Objective and quantitative evaluation of scar color using the L*a*b* color coordinates.

Scar color evaluation by clinical physicians has been based on subjective judgments. The purpose of this study was to investigate the application of a novel photographic analysis to produce an objective and quantitative measurement of scar color using the L*a*b* color coordinates. Three plastic surgeons evaluated photos of 207 scars using the clinical scar assessment scale developed by Beausang et al. Scar color was subjectively classified as group 1 (perfect match), 2 (slight mismatch), 3 (obvious mismatch), or 4 (gross mismatch). Three general physicians quantified color differences between the scar and the surrounding normal skin using the L*a*b* color coordinates. The total color difference (DeltaT*) and the color differences for each coordinate (DeltaL*, Deltaa*, and Deltab*) were calculated. The measurement was performed 3 times with a 4-week interval. Group 1 contained 51 scars, group 2 had 68, group 3 had 46, and group 4 had 42. The mean (SD) total color difference values (DeltaT*) for each group were 4.4 (1.83), 9.55 (2.18), 17.76 (2.96), and 29.06 (9.45), respectively (P < 0.001). The mean of each color coordinate (DeltaL* = light to dark, and Deltaa* = green to red) also differed between the groups, except in groups 1 and 2. The mean Deltab* (blue to yellow) did not differ between the groups. The correlation coefficients for interrater reliability and test-retest consistency were satisfactory. Objective scar evaluation using the L*a*b* color coordinates is found to be a reliable method to quantify scar color. With further study, this method could be simple and effective to assess the effects of scar management.