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AmnioCord Use Associated with Reduced Risk of Urethrocutaneous Fistula Recurrence among Hypospadias Patients
ZoŽ G. Baker, PhD, MPH1, Jullet Han, MD2, Hatim Thaker, MD2, Melissa Trabold, MSN1, Andy Chang, MD1.
1Children's Hospital Los Angeles, Los Angeles, CA, USA, 2University of Southern California, Los Angeles, CA, USA.

Background: Complications following hypospadias repairs occur more frequently than we would like, with the majority being urethrocutaneous fistulas (UCF). Moreover, unsuccessful UCF repairs are also common; previous studies have reported that up to 34% of patients experience re-fistulization or wound breakdown. The use of extracellular matrices (ECM) has become a novel addition to UCF repair following hypospadias revision. AmnioCord is one such ECM, consisting of a human-derived umbilical cord cellular allograft that preserves the innate collagen, proteoglycan, hyaluronic acid scaffolding, and contains wound-healing molecules. The aim of this study is to identify whether the use of AmnioCord during fistula repair is associated with reduced incidence of subsequent fistula among pediatric patients who developed UCF after hypospadias repair. Methods: Electronic medical records were accessed to capture retrospective data from patients who received at least one fistula repair surgery from June 2016 to July 2017 at a pediatric hospital in a large urban setting. Successful fistula closure was defined as a lack fistula recurrence from the time of surgical repair through July 2018. Crude and adjusted generalized estimating equations (GEE) with independent correlation structures were used to assess the association between AmnioCord use and surgical success, while controlling for repeated measures. Covariates were included in GEE models as needed to adjust for confounding variables. Results: Our study includes 60 patients who developed at least one fistula after hypospadias repair, and captures 89 fistula repair surgeries. Median age at first fistula repair was 2.9 years (IQR 1.8-4.9 years). The number of fistula presentations per patient ranged from one to five; while most patients (60%) had only one fistula, 25% presented with two subsequent fistulas, while 15% presented with three or more subsequent fistulas. Of all 60 patients, 33 (55%) had AmnioCord used during at least one repair. Fistula repair success rate was 58.4% overall, but significantly differed by AmnioCord use. Repair success rate was 72.2% among cases receiving AmnioCord, vs. 49.1% among cases receiving the standard of care (p=0.02). Older patients may have greater odds of surgical success, but this trend was not statistically significant (p=0.33). After controlling for patient age, patients who received AmnioCord had 2.89 times greater odds of surgical success than patients who did not receive AmnioCord (95% CI: 1.27-6.86; p=0.02). Patients who received AmnioCord were not significantly different than patients who did not receive AmnioCord regarding age, number of previous fistula repairs, comorbidities, or any other covariates of interest. Conclusions: This study provides evidence for a positive association between AmnioCord usage and successful fistula closure among pediatric patients who developed UCF following hypospadias repair. As current rates of fistula formation following hypospadias repair are high, and hypospadias is common, the use of AmnioCord and similar extracellular matrices may have a large impact on surgical success rates, and lead to reduced surgical morbidity and improved patient satisfaction.


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