Clinical Efficacy of Ovine Forestomach Matrix and Collagen/oxidized Regenerated Cellulose for the Treatment of Venous Leg Ulcers: An Interim Analysis of Retrospective Comparative Real-world Evidence

Introduction: Venous leg ulcers (VLUs) are traditionally managed with standard of care dressings, compression, and appropriate adjunctive venous interventions for pathologic venous reflux. Due to pathophys- iological complexity and underlying patient co-morbidities, conduct- ing randomized controlled trials to evaluate comparative efficacy of advanced treatment modalities is difficult as many patients would likely be excluded. This retrospective, pragmatic, real-world evidence (RWE) study compared the healing outcomes of VLUs treated with either ovine forestomach matrix (OFM) (n=312) or collagen/oxidized regenerated cel- lulose (ORC) (n=239) in outpatient wound care centers. Unlike restrictive randomized controlled trials, minimal inclusion and exclusion criteria were applied to create two treatment cohorts that reflected the general VLU population. The purpose of this retrospective, pragmatic real-world evidence (RWE) study was to compare the healing outcomes of venous leg ulcers (VLU) treated with ovine forestomach matrix (OFM^) or colla- gen/oxidized regenerated cellulose (collagen/ORC*). Methods: Cohorts consisted of VLUs treated with OFM or collagen/ ORC. Data was extracted from a wound database from 2014 to 2020, rep- resenting 449 wound care centers across the United States. The median time to wound closure and the percentage of wounds closed at various timepoints were estimated using Kaplan-Meier survival analysis. The per- centage of VLUs closed were statistically compared between treatment groups using Greenwood’s standard error estimates. Results: The 511 patients included in the study represented 830 total VLU, of which 470 were treated with OFM and 360 were treated with collagen/ORC. OFM demonstrated a significantly faster median time to closure (11.1±0.6 weeks) compared to the collagen/ORC group (12.3±1.0 weeks) (p=0.045). Cox proportional hazards analysis demonstrated that OFM-treated VLUs had significantly greater probability of healing (up to ~40%). The incidence of closure at 12-, 24- and 36-weeks was increased in OFM-treated VLUs relative to the collagen/ORC cohort.