Measuring vascularity of hypertrophic scars by dermoscopy: Construct validity and predictive ability of scar thickness change

Background: Vascularity of hypertrophic scar is a key indicator of scar maturation and a vital parameter of evaluating effects of scar management interventions. This study aims to explore the construct validity of dermoscopy for measuring vascularity of hypertrophic scar and its predictive ability of scar thickness change. Methods: Patients with hypertrophic scars were recruited for scar assessments at baseline and at one-month follow-up, which consisted of the Patient and Observer Scar Assessment Scale, DermaLab Combo, ultrasound and dermoscopy. Results: Forty hypertrophic scars in the active proliferation stage were included in this study. The dermoscopic measurements based on color significantly discriminated the hypertrophic scars from the healthy skin (P <.001). In addition, they showed moderate to strong correlations with the vascularity component of the Patient and Observer Scar Assessment Scale (r = −.438, P <.01; r = −.461, P <.01; and r = −.437, P <.01) and the erythema value as measured by DermaLab Combo (r = −.474, P <.01; r = −.603, P <.01; and r = −.498, P <.01). Weak to moderate correlations of the micro-vessel percentage were observed with the vascularity of Patient and Observer Scar Assessment Scale (r =.385, P <.01) and the erythema of DermaLab Combo (r =.444, P <.01). For prediction of the scars with high risk of thickness change, the green value by dermoscopy was the strongest predictor (AUC = 0.738, P =.034, 95%CI = 0.570-0.906). Conclusion: Dermoscopy, which evaluates scar vascularity by measuring scar color and micro-vessel percentage, could be used as an objective assessment tool to indicate scar maturation and identify scars with active proliferation.