Author: Deng, Huan
Title: The study of scar vascularity measurement and effect of controlling vascularity by pulsed dye laser on managing hypertrophic scars
Advisors: Li-Tsang, Cecilia (RS)
Degree: Ph.D.
Year: 2020
Award: FHSS Faculty Distinguished Thesis Award (2020/21)
Subject: Skin -- Blood-vessels
Dye lasers
Hypertrophic scars -- Treatment
Scars -- Treatment
Hong Kong Polytechnic University -- Dissertations
Department: Department of Rehabilitation Sciences
Pages: 179 pages : color illustrations
Language: English
Abstract: Background: Scar vascularity is a key indicator of scar maturation. Measurement of scar vascularity monitors scar change and guides targeted interventions to prevent excessive scarring and achieve promising outcomes. However, there is no consensus on the assessment tools for scar vascularity measurement. Given that vascularity of hypertrophic scar significantly increases at an early stage and plays an important role in hypertrophic scar development, controlling scar vascularity at an early stage might be an effective way to limit scar growth and promote scar maturation. As one type of laser therapy, pulsed dye laser (PDL) directly causes damage to scar microvascular structures and has preliminarily shown its effect on managing hypertrophic scars. However, the relationship between controlling scar vascularity by PDL and limiting scar growth is not fully understood. Objectives: This study consists of two phases, measurement and control of scar vascularity. Phase one aims to systematically review clinical tools on scar vascularity measurement (Chapter Two) and validate the use of dermoscopy to measure scar vascularity (Chapter Three). Phase two aims to explore the effect of controlling scar vascularity by PDL on managing hypertrophic scars (Chapter Four). Methods: Chapter two is a systematic review by searching PubMed, CINAHL, Embase and Science Direct databases. Studies, which used non-invasive measurement tools and explored their clinimetric properties, were identified and included. Chapter three is a longitudinal exploratory study. 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 (POSAS), DermaLab Combo, ultrasound and dermoscopy. Chapter Four is a 3-month assessor-blinded experimental study. Patients with hypertrophic scars less than one year after injury were enrolled into the PDL group or the control group. Patients in the PDL group received three PDL sessions at 4-week intervals. A total of three assessments were performed, at baseline, 1 month and 3 months, consisting of the POSAS and objective measurements of scar erythema, blood perfusion and scar thickness.
Results: (Chapter Two) A total of 1458 articles were obtained, and 26 articles were finally included in this review. Subjective vascularity measurement scales include the POSAS, the Vancouver Scar Scale (VSS) and the modified Vancouver Scar Scale (mVSS), while objective vascularity measurement devices consist of the color-measuring device, the blood flow measuring device and the morphological imaging device. (Chapter Three) Forty hypertrophic scars at 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 < 0.001). In addition, they showed moderate to strong correlations with the vascularity component of the POSAS (r = -0.438, p < 0.01; r = -0.461, p < 0.01; and r = -0.437, p < 0.01) and the erythema value as measured by DermaLab Combo (r = -0.474, p < 0.01; r = -0.603, p < 0.01; and r = -0.498, p < 0.01). For prediction of the scars with high risk of thickness change, the green value by dermoscopy was the strongest predictor (AUC = 0.738, p = 0.034, 95%CI = 0.570-0.906). (Chapter Four) A total of 45 patients were enrolled, 22 in the PDL group and 23 in the control group. After the 3-month treatment, parameters of scar vascularity (p = 0.003), pigmentation (p = 0.026), color (p < 0.001), thickness (p < 0.05) and overall scores (p < 0.01) on the POSAS significantly decreased in the PDL group. Moreover, objective measurements of scar erythema and blood perfusion showed significant improvements in the PDL group (p = 0.009 and p = 0.022, respectively) but not in the control group (p = 0.296 and p = 0.115, respectively). In addition, patients in the PDL group maintained a stable scar thickness compared to the control group which significantly increased from baseline, 1 month to 3 months (p < 0.01). Conclusion: Subjective scales are easy to use and have acceptable reliability to give a preliminary impression of scar vascularity. Three types of objective devices are not equivalent to measure scar vascularity. Dermoscopy, which measures scar color and provides a view of scar vascular structures, could be an objective tool of measuring scar vascularity. In addition, PDL, which improves scar erythema and poor perfusion, is recommended for immature and erythematous hypertrophic scars to limit scar thickness growth and promote scar maturation.
Rights: All rights reserved
Access: open access

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