Poor outcomes for children on the wait list at low-volume kidney transplant centers in the United States.

BACKGROUND: Low case volume has been associated with worse survival outcomes in solid organ transplantation. Our aim was to analyze wait-list outcomes in conjunction with posttransplant outcomes. METHODS: We studied a cohort of 11,488 candidates waitlisted in the Organ Procurement and Transplantation Network (OPTN) for pediatric kidney transplant between 2002 and 2014, including both deceased- and living-donor transplants; 8757 (76 %) candidates received a transplant. Candidates were divided into four groups according to the average volume of yearly transplants performed in the listing center over a 12-year period: more than ten, six to nine, three to five, and fewer than three. We used multivariate Cox regression analysis to identify independent risk factors for wait list and posttransplant mortality. RESULTS: Twenty-seven percent of candidates were listed at low-volume centers in which fewer than three transplants were performed annually. These candidates had a limited transplant rate; only 49 % received a transplant versus 88 % in high-volume centers (more than ten transplants annually) (p < 0.001). Being listed at a low-volume center showed a fourfold increased risk for death while on the wait list [hazard ratio (HR) 4.0 in multivariate Cox regression and 6.1 in multivariate competing risk regression]. It was not a significant risk factor for posttransplant death in multivariate Cox regression. CONCLUSIONS: Pediatric transplant candidates are listed at low-volume transplant centers are transplanted less frequently and have a much greater risk of dying while on the wait list. Further studies are needed to elucidate the reasons behind the significant outcome differences.

Waiting list outcomes in pediatric lung transplantation: Poor results for children listed in adult transplant programs.

BACKGROUND: Low case volume has been associated with lower survival after pediatric lung transplantation. Our aim was to analyze waitlist outcomes among pediatric lung transplant centers in the USA. METHODS: We studied a cohort of 1,139 pediatric candidates listed in the Organ Procurement and Transplantation Network for lung transplantation between 2002 and 2014. Of these candidates, 720 (63.2%) received a transplant. Candidates were divided into groups according to the clinical activity of the center of listing: high-volume pediatric (≥4 transplants per year); low-volume pediatric (<4 transplants per year); and adult (transplant volume predominantly in adults). We used multivariate Cox regression analysis to identify independent risk factors for waitlist mortality. We also determined the transplant rate-or likelihood of transplant after listing-over the study period. RESULTS: Fifty-eight percent of the children and adolescents were listed in adult centers where the resultant transplant rate was low-only 42% received a transplant compared with 93% in pediatric programs. Listing in an adult program was also the most significant risk factor for death on the waiting list (hazard ratio 15.6, 95% confidence interval 5.8 to 42.1). CONCLUSIONS: Most children (58%) are listed for lung transplantation in adult centers and have a reduced rate of transplantation and a greater chance of waitlist mortality.

Remodeling of ECM patch into functional myocardium in an ovine model: A pilot study.

BACKGROUND: Previous studies have demonstrated that surgical patches comprised of small intestinal submucosa-derived extracellular matrix (ECM) have biological remodeling potential. This pilot study investigated histological, mechanical, and bioelectrical properties of an ECM patch implanted in the ovine right-ventricular outflow tract (RVOT). MATERIALS AND METHODS: ECM patches (2 × 2 cm2 ) were implanted in four Western Range sheep (wether males, 37-49 kg, age <1 year) and explanted at 5 months (n = 2) and 8 months (n = 2). In vivo analysis included epicardial echocardiography and contact electrical mapping. Optical mapping was used to map electrical activity of two hearts on a Langendorff preparation. Mechanical testing quantified stiffness. Histological stains characterized structure, neovascularization, and calcification; immunohistochemistry (IHC) assessed cell phenotype. RESULTS: In vivo analysis showed that ECM patch tissue was contractile by M-mode and two-dimensional echocardiographic evaluation. In vivo electrical mapping, and optical mapping confirmed that ECM conducted an organized electrical signal. Mechanical testing of native and ECM patched RVOT tissue showed an elastic modulus of the implanted patch comparable to native tissue stiffness. CONCLUSIONS: At 5 and 8 months, the ECM had undergone extracellular matrix remodeling and neovascularization without calcification. The ECM was populated with locally aligned muscle cells positive for sarcomeric alpha-actinin, CD45, and troponin I and T. In sheep, the ECM patch appears to have the potential of remodeling to resemble native, functional ventricular tissue as evidenced by histological, mechanical, and electrical properties. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1713-1720, 2016.

Lung retransplantation in children: appropriate when selectively applied.

BACKGROUND: Lung retransplantation (re-LTx) in children has been associated with lower survival rates compared with primary lung transplantation. However, improving survival for primary LTx has led to more patients presenting for re-LTx. Therefore, an analysis of the UNOS (United Network of Organ Sharing) database to evaluate the effectiveness of pediatric lung retransplantation in the United States was completed. METHODS: The UNOS registry was queried for pediatric re-LTx patients from May 1988 to May 2008. There were 81 (10%) re-LTx out of a total 802 pediatric lung transplants. RESULTS: Median age and weight at re-LTx were 14 (range, 0 to 18) years and 32 (4 to 58) kg. Indications for re-LTx were obliterative bronchiolitis in 50 patients (62%), primary graft failure in 8 (10%), and other in 23 (28%). The Kaplan-Meier graft survival for re-LTx patients was worse than for primary transplant patients (p < 0.001, graft half-life 0.9 vs 4.0 years), especially if re-LTx was done less than 1 year after primary transplant (graft half-life 0.25 years). Graft survival in patients who underwent re-LTx greater than 1 year after primary transplant was not statistically different than for primary LTx patients (p = 0.21; graft half-life 2.8 vs 4.0 years), and if re-LTx greater than 1 year posttransplant occurred in patients who were not ventilator dependent, survival was further improved (p = 0.68; graft half-life 4.7 vs 4.0 years). CONCLUSIONS: Pediatric lung retransplantation within the first year after primary transplant does not appear advisable. Pediatric re-LTx greater than 1 year after primary transplantation may be a reasonable strategy for end-stage graft failure. Patients greater than 1 year posttransplant and not ventilator dependent appear an even more compelling group in which to consider lung retransplantation.