Center Variation in Indication and Short-Term Outcomes after Pediatric Heart Transplantation: Analysis of a Merged United Network for Organ Sharing - Pediatric Health Information System Cohort

The relationship between center-specific variation in indication for pediatric heart transplantation and short-term outcomes after heart transplantation is not well described. We used merged patient- and hospital-level data from the United Network for Organ Sharing and the Pediatric Health Information Systems to analyze outcomes according to transplant indication for a cohort of children (≤ 21 years old) who underwent heart transplantation between 2004 and 2015. Outcomes included 30-day mortality, transplant hospital admission mortality, and hospital length of stay, with multivariable adjustment performed according to patient and center characteristics. The merged cohort reflected 2169 heart transplants at 20 U.S. centers. The median number of transplants annually at each center was 11.6, but ranged from 3.5 to 22.6 transplants/year. Congenital heart disease was the indication in the plurality of cases (49.2%), with cardiomyopathy (46%) and myocarditis (4.8%) accounting for the remainder. There was significant center-to-center variability in congenital heart disease as the principal indication, ranging from 15% to 66% (P < 0.0001). After adjustment, neither center volume nor proportion of indications for transplantation were associated with 30-day or transplant hospital admission mortality. In this large, merged pediatric cohort, variation was observed at center level in annual transplant volume and prevalence of indications for heart transplantation. Despite this variability, center volume and proportion of indications represented at a given center did not appear to impact short-term outcomes.

Decline of increased risk donor offers increases waitlist mortality in paediatric heart transplantation

BACKGROUND

Increased risk donors in paediatric heart transplantation have characteristics that may increase the risk of infectious disease transmission despite negative serologic testing. However, the risk of disease transmission is low, and refusing an IRD offer may increase waitlist mortality. We sought to determine the risks of declining an initial IRD organ offer.

METHODS AND RESULTS

We performed a retrospective analysis of candidates waitlisted for isolated PHT using 20072017 United Network of Organ Sharing datasets. Match runs identified candidates receiving IRD offers. Competing risks analysis was used to determine mortality risk for those that declined an initial IRD offer with stratified Cox regression to estimate the survival benefit associated with accepting initial IRD offers. Overall, 238/1067 (22.3%) initial IRD offers were accepted. Candidates accepting an IRD offer were younger (7.2 versus 9.8 years, p < 0.001), more often female (50 versus 41%, p = 0.021), more often listed status 1A (75.6 versus 61.9%, p < 0.001), and less likely to require mechanical bridge to PHT (16% versus 23%, p = 0.036). At 1- and 5-year follow-up, cumulative mortality was significantly lower for candidates who accepted compared to those that declined (6% versus 13% 1-year mortality and 15% versus 25% 5-year mortality, p = 0.0033). Decline of an IRD offer was associated with an adjusted hazard ratio for mortality of 1.87 (95% CI 1.24, 2.81, p < 0.003).

CONCLUSIONS

IRD organ acceptance is associated with a substantial survival benefit. Increasing acceptance of IRD organs may provide a targetable opportunity to decrease waitlist mortality in PHT.

Learning networks in pediatric heart failure and transplantation

BACKGROUND

Learning networks have emerged in medicine as a novel organizational structure that contains elements of quality improvement, education, and research with the goal of effecting rapid improvements in clinical care. In this article, the concept of a learning network is defined and highlighted in the field of pediatric heart failure and transplantation.

METHODS

Learning networks are defined, with particular attention paid to the recent creation of the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) for children with heart failure and those being supported with ventricular assist devices (VAD).

RESULTS

The mission, goals, and organizational structure of ACTION are described, and recent initiatives promoted by ACTION are highlighted, such as stroke reduction initiatives, practice harmonization protocols, and use of ACTION data to support the recent US Food and Drug Administration approval of newer VAD for pediatric patients.

CONCLUSIONS

The learning network, exemplified by ACTION, is distinguished from traditional clinical research collaboratives by contributions in research, quality improvement, patient-reported outcomes, and education, and serves as an effective vehicle to drive clinical improvement in the care of children with advanced heart failure.

Clinical and hemodynamic characteristics of the pediatric failing Fontan

AIM

To describe the clinical and hemodynamic characteristics of Fontan failure in children listed for heart transplant.

METHODS

In a nested study of the Pediatric Heart Transplant Society, 16 centers contributed information on Fontan patients listed for heart transplant between 2005and 2013. Patients were classified into four mutually exclusive phenotypes: Fontan with abnormal lymphatics (FAL), Fontan with reduced systolic function (FRF), Fontan with preserved systolic function (FPF), and Fontan with "normal" hearts (FNH). Primary outcome was waitlist and post-transplant mortality.

RESULTS

177 children listed for transplant were followed over a median 13 (IQR 4-31) months, 84 (47%) were FAL, 57 (32%) FRF, 22 (12%) FNH, and 14 (8%) FPF. Hemodynamic characteristics differed between the 4 groups: Fontan pressure (FP) was most elevated with FPF (median 22, IQR 18-23, mmHg) and lowest with FAL (16, 14-20, mmHg); cardiac index (CI) was lowest with FRF (2.8, 2.3-3.4, L/min/m²). In the entire cohort, 66% had FP >15 mmHg, 21% had FP >20 mmHg, and 10% had CI <2.2 L/min/m². FRF had the highest risk of waitlist mortality (21%) and FNH had the highest risk of post-transplant mortality (36%).

CONCLUSIONS

Elevated Fontan pressure is more common than low cardiac output in pediatric failing Fontan patients listed for transplant. Subtle hemodynamic differences exist between the various phenotypes of pediatric Fontan failure. Waitlist and post-transplant mortality risks differ by phenotype.

Favorable outcomes after heart transplantation in Barth syndrome

BACKGROUND

Barth Syndrome (BTHS) is a rare, X-linked disease characterized by cardioskeletal myopathy and neutropenia. Comparative outcomes after heart transplantation have not been reported.

METHODS

We identified BTHS recipients across 3 registries (Pediatric Heart Transplant Study Registry [PHTS], Barth Syndrome Research Registry and Repository, and Scientific Registry of Transplant Recipient-Pediatric Health Information System) and matched them 1:4 to non-BTHS, male heart transplant (HT) recipients listed with dilated cardiomyopathy in PHTS. Demographics and survival data were analyzed for all recipients, whereas post-HT infection, malignancy, allograft vasculopathy, and acute rejection were only available for analysis for individuals with PHTS data.

RESULTS

Forty-seven BTHS individuals with 51 listings and 43 HTs (including 2 re-transplants) were identified. Age at primary HT was 1.7 years (IQR: 0.6-4.5). Mechanical circulatory support at HT was common (ventricular assist device 29%, extracorporeal membrane oxygenation 5%). Over a median follow-up of 4.5 years (IQR 2.7-9.1), survival for BTHS HT recipients was no different than non-BTHS HT recipients (HR 0.91, 95% CI 0.40-2.12, p = 0.85). Among those with PHTS data (n = 28), BTHS HT recipients showed no difference in freedom from infection (HR 0.64, 0.34-1.22; p = 0.18), malignancy (HR 0.22, 0.02-2.01, p = 0.18), and allograft vasculopathy (HR 0.58, 0.16-2.1, p = 0.41). Freedom from acute rejection (HR 0.39, 0.17-0.86, p = 0.02) was greater for BTHS HT recipients despite similar use of induction (61 vs 73%, p = 0.20), steroids at 30-days (75 vs 62%, p = 0.27), and dual/triple drug immunosuppression at 1-year (80 vs 84%, p = 0.55).

CONCLUSIONS

In this largest cohort yet reported, individuals with BTHS have equivalent survival with less acute rejection and no difference in infection or malignancy after HT. When indicated, HT for individuals with BTHS is appropriate.

Quality Metrics in Solid Organ Transplantation: A Systematic Review

BACKGROUND

The best approach for determining whether a transplant program is delivering high-quality care is unknown. This review aims to identify and characterize quality metrics in solid organ transplantation.

METHODS

Medline, Embase, and Cochrane Central Register of Controlled Trials were searched from inception until February 1, 2017. Relevant full text reports and conference abstracts that examined quality metrics in organ transplantation were included. Two reviewers independently extracted study characteristics and quality metrics from 52 full text reports and 24 abstracts. PROSPERO registration: CRD42016035353.

RESULTS

Three hundred seventeen quality metrics were identified and condensed into 114 unique indicators with sufficient detail to be measured in practice; however, many lacked details on development and selection, were poorly defined, or had inconsistent definitions. The process for selecting quality indicators was described in only 5 publications and patient involvement was noted in only 1. Twenty-four reports used the indicators in clinical care, including 12 quality improvement studies. Only 14 quality metrics were assessed against patient and graft survivals.

CONCLUSIONS

More than 300 quality metrics have been reported in transplantation but many lacked details on development and selection, were poorly defined, or had inconsistent definitions. Measures have focused on safety and effectiveness with very few addressing other quality domains, such as equity and patient-centeredness. Future research will need to focus on transparent and objective metric development with proper testing, evaluation, and implementation in practice. Patients will need to be involved to ensure that transplantation quality metrics measure what is important to them.

Haemodynamic profiles of children with end-stage heart failure

Aims

To evaluate associations between haemodynamic profiles and symptoms, end-organ function and outcome in children listed for heart transplantation.

Methods and results

Children <18 years listed for heart transplant between 1993 and 2013 with cardiac catheterization data [pulmonary capillary wedge pressure (PCWP), right atrial pressure (RAP), and cardiac index (CI)] in the Pediatric Heart Transplant Study database were included. Outcomes were New York Heart Association (NYHA)/Ross classification, renal and hepatic dysfunction, and death or clinical deterioration while on waitlist. Among 1059 children analysed, median age was 6.9 years and 46% had dilated cardiomyopathy. Overall, 58% had congestion (PCWP >15 mmHg), 28% had severe congestion (PCWP >22 mmHg), and 22% low cardiac output (CI < 2.2 L/min/m2). Twenty-one per cent met the primary outcome of death (9%) or clinical deterioration (12%). In multivariable analysis, worse NYHA/Ross classification was associated with increased PCWP [odds ratio (OR) 1.03, 95% confidence interval (95% CI) 1.01-1.07, P = 0.01], renal dysfunction with increased RAP (OR 1.04, 95% CI 1.01-1.08, P = 0.007), and hepatic dysfunction with both increased PCWP (OR 1.03, 95% CI 1.01-1.06, P < 0.001) and increased RAP (OR 1.09, 95% CI 1.06-1.12, P < 0.001). There were no associations with low output. Death or clinical deterioration was associated with severe congestion (OR 1.6, 95% CI 1.2-2.2, P = 0.002), but not with CI alone. However, children with both low output and severe congestion were at highest risk (OR 1.9, 95% CI 1.1-3.5, P = 0.03).

Conclusion

Congestion is more common than low cardiac output in children with end-stage heart failure and correlates with NYHA/Ross classification and end-organ dysfunction. Children with both congestion and low output have the highest risk of death or clinical deterioration.

Elevated pretransplant pulmonary vascular resistance index does not predict mortality after isolated orthotopic heart transplantation in children: A retrospective analysis of the UNOS database

OHT is the definitive therapy in end-stage heart failure. Elevated PVRI is considered a relative contraindication to isolated OHT; this assumption is re-evaluated using data from the UNOS database. A retrospective review of de-identified data from the UNOS dataset was performed. There were 1943 pediatric OHT recipients between 10/87 and 12/11 with sufficient data for analysis. Cox regression was performed to examine the effect of baseline characteristics on post-transplant survival. Patients were propensity matched, and Kaplan-Meier survival analysis was performed comparing cohorts of patients using thresholds of 6 and 9 WU × m(2) . PVRI was not a significant predictor of post-transplant outcomes in either univariate or multivariate Cox regression. Kaplan-Meier analysis revealed no difference in survival between both unmatched and propensity-matched OHT recipients. In conclusion, elevated PVRI was not associated with post-transplant mortality in pediatric OHT recipients. A prospective study assessing the current use of PVRI ≥6 as a threshold to contraindicate isolated OHT should be undertaken. Removing this potentially unnecessary restriction on transplant candidacy may make this life-saving therapy available to a greater number of patients.

Can linking databases answer questions about paediatric heart failure?

Numerous data sets collect information on patients with paediatric cardiovascular disease, including paediatric heart failure and transplant patients. This review discusses methodologies available for linking and integrating information across data sets, which may help facilitate answering important questions in the field of paediatric heart failure and transplant that cannot be answered with individual data sets or single-centre data alone.

Regional variation in survival before and after pediatric heart transplantation--an analysis of the UNOS database

Geographic variation occurs in a variety of health outcomes. Regional influences on outcomes before and after listing for pediatric heart transplantation have not been assessed. Review of the UNOS dataset identified 5398 pediatric (≤ 18 years) patients listed for heart transplantation 2000-2011. Patients were stratified based on the region of listing. Regional-level variables were correlated with individual risk-adjusted outcomes. Mean time spent on the waitlist varied from 91.0 ± 163 days (Region 6 [R6]) to 248.1 ± 493 days (R4, p < 0.0001). Regions with more transplant centers (p < 0.0001) and fewer transplants (p = 0.0015) had higher waitlist mortality. Risk-adjusted individual waitlist mortality varied from 6.9% (R1, CI 6.2-7.8) to 19.2% (R5, CI 18.0-20.6). Waitlist mortality was higher for individuals awaiting transplant in regions with more listings per center (OR 1.04, CI 1.01-1.08) and lower in regions with more donors per center (OR 0.95, CI 0.90-0.99 per donor). Posttransplant risk-adjusted survival varied across regions (R4: 5.4%, CI 4.2-7.4; R7: 18.0%, CI 12.4-32.5), but regional variables were not correlated with outcomes. Outcomes among children undergoing heart transplantation vary by region. Factors leading to increased competition for donor allografts are associated with poorer waitlist survival. Equitable allocation of cardiac allografts requires further investigation of these findings.