Faster Than Projected Healing in Chronic Venous and Diabetic Foot Ulcers When Treated with Intact Fish Skin Grafts Compared to Expected Healing Times for Standard of Care: An Outcome-Based Model from a Swiss Hospital

Purpose: Inadequate response to wound management is defined as a reduction in the wound area of <40-50% following four weeks of standard of care (SOC) and should be managed with a skin substitute product. We set out to evaluate a novel outcome-based model focusing on the management of hard-to-heal venous leg ulcers (VLUs) and diabetic foot ulcers (DFUs) using SOC treatment or intact fish skin grafts (FSGs) in a regional hospital. Methods: We built an outcome-based model applying surrogate markers and endpoints of wound healing for VLU and DFU to determine the healing trajectory with SOC treatment. We could predict if VLU and DFU would heal by weeks 20 and 24, respectively, after four weeks of evaluating the initial wound area reduction. 51 patients were recruited (26 VLUs and 25 DFUs) and 42 wounds were randomized. 17 wounds deemed unlikely to heal by week 8 received management with FSG as per the Swiss Society for Dermatology and Venereology (SGDV) and the Swiss Association for Woundcare (SAfW) guidelines for the use of skin replacement products, and 26 wounds continued SOC for weeks 5-8. Results/Discussion: 12 wounds managed with FSG beat the modeled SOC healing predictions, with the majority healed >50% sooner and as early as <10% of the time than was predicted. Of these 17, five wounds failed to achieve the required size reduction in Week 4-8 (over 25% improvement in wound area vs. SOC). The FSG were assigned to treatment-resistant VLU and DFUs and were still able to heal these wounds most of the time and even changed the wound's healing trajectory that increased in size in the initial four weeks. Conclusion: This pilot study showed that management with FSG results in faster healing wounds than SOC predicted, while SOC-treated wounds mostly followed model predictions.