Interpretation of the DermaLab Combo® pigmentation and vascularity measurements in burn scar assessment: An exploratory analysis

Abstract

BackgroundThe DermaLab Combo® measures pigmentation and vascularity of a burn scar more reliably than the modified Vancouver Scar Scale (mVSS). This study aims to examine how the DermaLab Combo® continuous measurements of pigmentation and vascularity of burns scars relate to the mVSS, a standard clinical scar assessment method; and secondly, to obtain evidence to support the concurrent validity of DermaLab Combo® measurements for pigmentation and vascularity. MethodScar assessments were performed on an index burn scar of 100 subjects using two methods: the mVSS (two raters) and the DermaLab Combo® device (one rater). Using the DermaLab Combo®, measurements of pigmentation and vascularity for the index scar and an adjacent normal skin site were obtained. Indices were generated to represent the scar pigmentation (melanin index, MI%) and scar vascularity (erythema index, EI%) relative to the patient's matched normal skin. Exploratory univariate and bivariate analyses were conducted and the concordance of classification by mVSS score using DermaLab® cut-off values was assessed. ResultsFor pigmentation, the results suggest a 80% classification concordance for the DermaLab Combo® MI% values into mVSS pigmentation categories (hypopigmentation, normal pigmentation and hyperpigmentation) using two predictors (MI% and EI%) and visually fitted discriminant axis cut-offs. Due to the high degree of overlap of EI% values between the vascularity categories, meaningful classification of EI% values using the mVSS was not possible. ConclusionQuantifying percentage changes in melanin and erythema relative to matched normal skin improved understanding of the DermaLab Combo® pigmentation and vascularity measurements. The DermaLab Combo® pigmentation MI% values were able to be classified into pigmentation categories of the mVSS, and pigmentation classification concordance was further improved with consideration of the scar's DermaLab Combo® vascularity EI% values. The DermaLab Combo® is an objective tool; however, while the measurement provides continuous numerical data that may be useful for identifying change over time in clinical scar monitoring of pigmentation and vascularity, further work will be useful to understand the DermaLab Combo® measurements to optimise the interpretation of these data.