New evaluation method for postoperative scar redness

Even after successful operations, ugly postoperative skin scars are often distressing to patients and their parents. To judge the success of surgical methods and postoperative treatment, postoperative scars should be evaluated using a quantitative system. Height and width are easily measured, but scar redness is not. We have developed a simple and effective method for evaluating scar redness. According to the color definitions employed in computer graphics, each color can be expressed as RGB (red, green or blue) coordinates (r, g, b): 0 ≦ r, g, b ≦ 10. The degree of scar redness is defined by the following formula: redness score (RS) = (r₁ - r₀)² + (g₁ - g₀)² + (b₁ - b₀)². Here, (R₁, g₁, b₁) = coordinates of the scar color and (r₀, g₀, b₀) = coordinates of the surrounding skin color. RS was evaluated in 59 children (35 males, 24 females; ages 1 month to 12 years old) who had scar redness after congenital cardiac surgery. For each patient, scar color and surrounding skin color was identified on the color sample table. Scar redness was also evaluated by the conventional grading method: 1 = mild, 2 = moderate and 3 = severe. The RS of the colored scars ranged from 4 to 100 (38 ± 27). By the conventional grading method, 44 scars were grade 1, 15 grade 2 and none grade 3. RS was significantly higher among grade 2 than grade 1 patients, 52 ± 25 and 33 ± 27, respectively (P < 0.05). Given its subjectivity, the conventional grading method yields variable data; surrounding skin color, moreover, is not considered. Our new evaluation method using RS effectively and accurately defines scar and skin colors, and allows quantitative studies of these factors.