Clinical practice patterns are relatively uniform between pediatric heart transplant centers: A survey-based assessment

The teammate trial: Study design and rationale tacrolimus and everolimus against tacrolimus and MMF in pediatric heart transplantation using the major adverse transplant event (MATE) score

BACKGROUND

Currently there are no immunosuppression regimens FDA-approved to prevent rejection in pediatric heart transplantation (HT). In recent years, everolimus (EVL) has emerged as a potential alternative to standard tacrolimus (TAC) as the primary immunosuppressant to prevent rejection that may also reduce the risk of cardiac allograft vasculopathy (CAV), chronic kidney disease (CKD) and cytomegalovirus (CMV) infection. However, the 2 regimens have never been compared head-to-head in a randomized trial. The study design and rationale are reviewed in light of the challenges inherent in rare disease research.

METHODS

The TEAMMATE trial (IND 127980) is the first multicenter randomized clinical trial (RCT) in pediatric HT. The primary purpose is to evaluate the safety and efficacy of EVL and low-dose TAC (LD-TAC) compared to standard-dose TAC and mycophenolate mofetil (MMF). Children aged <21 years at HT were randomized (1:1 ratio) at 6 months post-HT to either regimen, and followed for 30 months. Children with recurrent rejection, multi-organ transplant recipients, and those with an estimated glomerular filtration rate (eGFR) <30 mL/min/1.73m² were excluded. The primary efficacy hypothesis is that, compared to TAC/MMF, EVL/LD-TAC is more effective in preventing 3 MATEs: acute cellular rejection (ACR), CKD and CAV. The primary safety hypothesis is that EVL/LD-TAC does not have a higher cumulative burden of 6 MATEs (antibody mediated rejection [AMR], infection, and post-transplant lymphoproliferative disorder [PTLD] in addition to the 3 above). The primary endpoint is the MATE score, a composite, ordinal surrogate endpoint reflecting the frequency and severity of MATEs that is validated against graft loss. The study had a target sample size of 210 patients across 25 sites and is powered to demonstrate superior efficacy of EVL/LD-TAC. Trial enrollment is complete and participant follow-up will be completed in 2023.

CONCLUSION

The TEAMMATE trial is the first multicenter RCT in pediatric HT. It is anticipated that the study will provide important information about the safety and efficacy of everolimus vs tacrolimus-based regimens and will provide valuable lessons into the design and conduct of future trials in pediatric HT.

Practice variation in the diagnosis of acute rejection among pediatric heart transplant centers: An analysis of the pediatric heart transplant society (PHTS) registry

BACKGROUND

Freedom from rejection in pediatric heart transplant recipients is highly variable across centers. This study aimed to assess the center variation in methods used to diagnose rejection in the first-year post-transplant and determine the impact of this variation on patient outcomes.

METHODS

The PHTS registry was queried for all rejection episodes in the first-year post-transplant (2010-2019). The primary method for rejection diagnosis was determined for each event as surveillance biopsy, echo diagnosis, or clinical. The percentage of first-year rejection events diagnosed by surveillance biopsy was used to approximate the surveillance strategy across centers. Methods of rejection diagnosis were described and patient outcomes were assessed based on surveillance biopsy utilization among centers.

RESULTS

A total of 3985 patients from 56 centers were included. Of this group, 873 (22%) developed rejection within the first-year post-transplant. Surveillance biopsy was the most common method of rejection diagnosis (71.7%), but practices were highly variable across centers. The majority (73.6%) of first rejection events occurred within 3-months of transplantation. Diagnosis modality in the first-year was not independently associated with freedom from rejection, freedom from rejection with hemodynamic compromise, or overall graft survival.

CONCLUSIONS

Rejection in the first-year after pediatric heart transplant occurs in 22% of patients and most commonly in the first 3 months post-transplant. Significant variation exists across centers in the methods used to diagnose rejection in pediatric heart transplant recipients, however, these variable strategies are not independently associated with freedom from rejection, rejection with hemodynamic compromise, or overall graft survival.

Practice variability in pediatric heart transplantation: opportunities for collaboration

The pediatric heart transplant population continues to grow and more centers are now providing advanced heart failure and transplant services. Though more patients are surviving after transplant, pediatric center protocols have remained relatively unchanged with limited research to guide protocol optimization. The authors explore recent literature reviewing the impact of the different approaches to pre and post-transplant care and as well as the impact these variations have on the field and future directions.

Center Variation in Hospital Costs for Pediatric Heart Transplantation: The Relationship Between Cost and Outcomes

There are limited published data addressing the costs associated with pediatric heart transplantation and no studies evaluating the variation in costs across centers. We aimed to describe center variation in pediatric heart transplant costs and assess the association of transplant hospitalization costs with patient outcomes. Using a linkage between the Pediatric Health Information System and Scientific Registry of Transplant Recipients databases, hospital costs were assessed for patients (< 18 years of age) undergoing heart transplantation (2007-2016). Severity-adjusted patient costs were calculated using generalized linear mixed-effects models with a random hospital intercept. Center variation in hospital cost was described after adjusting for the predicted risk of in-hospital mortality. Post-transplant survival was compared between low- and high-cost centers using Cox proportional hazard models. A total of 2156 patients were included from 24 centers. There was 3.7-fold variation in transplant hospitalization costs across centers, ranging from $329,477 to $1,226,507. Patients transplanted at high-cost centers have a higher predicted risk of in-hospital mortality (8.1% vs. 6.1%, p < 0.001). Both early (p = 0.008) and long-term (p = 0.003) post-transplant survival were better in patients transplanted at low-cost centers. Transplant at low-cost centers was associated with improved post-transplant survival, independent of patient-specific risk (adjusted hazard ratio 0.72; 95%CI 0.57-0.92, p = 0.008). There is wide variation in cost for pediatric heart transplant inpatient care among U.S. centers with low-cost centers demonstrating the best patient survival. Differences in patient populations likely contribute to these findings, but cannot account for all the variation seen. This suggests that variability in the delivery of care across centers may influence post-transplant survival.