SMOOTH protocol: A pilot randomised prospective intra-patient single-blinded observational study for examining the mechanistic basis of ablative fractional carbon dioxide laser therapy in treating hypertrophic scarring.

BACKGROUND: Burn injuries are the fourth most common type of trauma and are associated with substantial morbidity and mortality. The impact of burn injury is clinically significant as burn injuries often give rise to exuberant scarring. Hypertrophic scarring (HTS) is a particular concern as up to 70% of burns patients develop HTS. Laser therapy is used for treating HTS and has shown positive clinical outcomes, although the mechanisms remain unclear limiting approaches to improve its effectiveness. Emerging evidence has shown that fibroblasts and senescent cells are important modifiers of scarring. This study aims to investigate the cellular kinetics in HTS after laser therapy, with a focus on the association of scar reduction with the presence of senescent cells. METHODS: We will conduct a multicentre, intra-patient, single-blinded, randomised controlled longitudinal pilot study with parallel assignments to achieve this objective. 60 participants will be recruited to receive 3 interventional ablative fractional CO2 laser treatments over a 12-month period. Each participant will have two scars randomly allocated to receive either laser treatment or standard care. Biopsies will be obtained from laser-treated, scarred-no treatment and non-scarred tissues for immune-histological staining to investigate the longitudinal kinetics of p16INK4A+-senescent cells and fibroblast subpopulations (CD90+/Thy1+ and αSMA+). Combined subjective scar assessments including Modified Vancouver Scar Scale, Patient and Observer Scar Assessment Scale and Brisbane Burn Scar Impact Profile; and objective assessment tools including 3D-Vectra-H1 photography, DermaScan® Cortex, Cutometer® and ColoriMeter®DSMIII will be used to evaluate clinical outcomes. These will then be used to investigate the association between senescent cells and scar reduction after laser therapy. This study will also collect blood samples to explore the systemic biomarkers associated with the response to laser therapy. DISCUSSION: This study will provide an improved understanding of mechanisms potentially mediating scar reduction with laser treatment, which will enable better designs of laser treatment regimens for those living with HTS. TRIAL REGISTRATION: ClinicalTrials.gov: NCT04736251.

Outcomes important to burns patients during scar management and how they compare to the concepts captured in burn-specific patient reported outcome measures.

BACKGROUND: Pressure garment therapy (PGT) is an established treatment for the prevention and treatment of hypertrophic scarring; however, there is limited evidence for its effectiveness. Burn survivors often experience multiple issues many of which are not adequately captured in current PGT trial measures. To assess the effectiveness of PGT it is important to understand what outcomes matter to patients and to consider whether patient-reported outcome measures (PROMs) can be used to ascertain the effect of treatments on patients' health-related quality of life. This study aimed to (a) understand the priorities and perspectives of adult burns patients and the parents of burns patients who have experienced PGT via in-depth qualitative data, and (b) compare these with the concepts captured within burn-specific PROMs. METHODS: We undertook 40 semi-structured interviews with adults and parents of paediatric and adolescent burns patients who had experienced PGT to explore their priorities and perspectives on scar management. Interviews were audio-recorded, transcribed and thematically analysed. The outcomes interpreted within the interview data were then mapped against the concepts captured within burn-specific PROMs currently in the literature. RESULTS: Eight core outcome domains were identified as important to adult patients and parents: (1) scar characteristics and appearance, (2) movement and function, (3) scar sensation, (4) psychological distress, adjustments and a sense of normality, (5) body image and confidence, (6) engagement in activities, (7) impact on relationships, and (8) treatment burden. CONCLUSIONS: The outcome domains presented reflect a complex holistic patient experience of scar management and treatments such as PGT. Some currently available PROMs do capture the concepts described here, although none assess psychological adjustments and attainment of a sense of normality following burn injury. The routine use of PROMs that represent patient experience and their relative contribution to trial outcome assessment versus clinical measures is now a matter for further research and debate.