Simultaneous Versus Sequential Fractional CO2 Laser and Subcision Combination for Post-acne Atrophic Scars: A Split-face Comparative Study.

Plain-language summary

Acne vulgaris, a disease of the pilosebaceous unit, is estimated to afflict 9.4% of the global population, making it the eighth most prevalent and third most significant disease according to the global burden of disease. Post-acne atrophic scars may develop in 95% of acne patients due to aberrant wound healing that affects the pilosebaceous unit and surrounding tissue. Scars are cosmetically unattractive, contributing to the severe psychosocial discomfort observed in acne vulgaris patients. Several approaches exist for the treatment of post-acne atrophic scars, depending on various factors such as the individual's condition, the types of scars present, and the associated expenses. However, treating atrophic acne scars remains challenging for physicians because there is no gold-standard treatment. Thus, combinations of interventions are typically necessary. Fractional CO2 laser and subcision are therapeutic methods proven to be effective in treating post-acne atrophic scars. By creating hundreds of thousands of micro-heat treatment zones (MTZs), fractional CO2 lasers emitting small focal spots (50-80 m) via high-focusing mirrors can efficiently treat acne scars. These thermal damage columns accelerate the healing process of collagen synthesis. Subcision, which can be safely paired with other operations, should be the initial step in treating acne scars since it separates scars from underlying structures. Although several studies proposed that the combination of fractional CO2 laser and subcision was more efficacious than a single therapeutic modality, no study has to date compared the efficacy and safety of simultaneous versus sequential combination of these two methods in the treatment of post-acne atrophic scars. There is a critical need for basic research on the effectiveness and adverse events of combining modalities sequentially as compared to simultaneously due to the high expense of traveling and the downtime needed to recover after each treatment, especially for diseases requiring long-term and periodic intervention such as post-acne atrophic scars. Wound healing is a dynamic process with four distinct but overlapping phases: hemostasis, inflammation, proliferation, and remodeling. The proliferation phase, during which new tissue is formed by a matrix of collagen, elastin, glycosaminoglycans, and other fibrous proteins, begins about four to twenty-one days following an injury. If sequential modalities interfere with each other's proliferative processes, therapeutic efficacy may be compromised. Therefore, our working hypothesis that simultaneous combination is more effective than sequential combination is based on the fact that if the wound-healing process is interrupted, it may stop or progress inadequately. In addition, the investigators anticipate no significant difference between these methods in terms of adverse events frequency and severity, but the downtime in the sequential combination group might be greater than that of the simultaneous combination group. The investigators propose to test the hypothesis by addressing the following two specific aims: Aim 1: to compare the efficacy and patient satisfaction of simultaneous versus sequential treatment using fractional CO2 laser plus subcision. Aim 2: To compare adverse reactions of simultaneous and sequential treatment using fractional CO2 laser plus subcision. Upon completion of this study, the investigators will have (a) compared the treatment outcome of simultaneously versus sequentially combined fractional CO2 laser plus subcision based on ECCA clinical grading score, patient satisfaction, and skin thickness via high-frequency ultrasonography; and (b) compared the incidence and duration of adverse events in simultaneous versus sequential treatment. Optimizing the combination of different interventions will contribute to more efficacious and economical treatment protocols for post-acne atrophic scars.

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