Successful merging of data from the United Network for Organ Sharing and the Pediatric Health Information System databases

Outcomes of Concomitant Cardiac Surgical Procedures Performed During Pediatric Lung Transplantation in the United States

Data on concomitant cardiac surgery (CCS) performed during pediatric lung transplantation (LTx) is limited. Therefore, we conducted a multi-institutional analysis to identify the incidence and outcomes of CCS in pediatric (< 18 years) LTx recipients by merging data (2004-2023) from the United Network for Organ Sharing (UNOS) and Pediatric Health Information System (PHIS) databases. Of the total of 596 pediatric LTx recipients, 87 (15%) underwent CCS. The majority of these cardiac surgeries were atrial septal defect (ASD) closure (90%) followed by aortic arch/descending aortic repair (3%), atrial repair (3%), ventricular septal defect closure (2%), patent ductus arteriosus ligation (2%), and tricuspid valve repair (2%). The median age at LTx was 3 years (IQR: 0-12). Pulmonary hypertension (PHT) was the predominant indication for LTx (54%). Survival to discharge was 94% and 5-years survival was 64%. Our findings indicate CCS in children undergoing LTx has acceptable outcomes.

The majority of pediatric Fontan patients have excellent post-transplant survival

OBJECTIVE

Many pediatric Fontan patients require heart transplant, but this cohort is understudied given the difficulty in identifying these patients in national registries. We sought to characterize survival post-transplant in a large cohort of pediatric patients undergoing the Fontan.

METHODS

The United Network for Organ Sharing and Pediatric Health Information System were used to identify Fontan heart transplant recipients aged less than 18 years (n = 241) between 2005 and 2022. Decompensation was defined as the presence of extracorporeal membrane oxygenation, ventilation, hepatic/renal dysfunction, paralytics, or total parenteral nutrition at transplant.

RESULTS

Median age at transplant was 9 (interquartile range, 5-12) years. Median waitlist time was 107 (37-229) days. Median volume across 32 center was 8 (3-11) cases. Approximately half (n = 107, 45%) of recipients had 1A/1 initial listing status. Sixty-four patients (28%) were functionally impaired at transplant, 10 patients (4%) were ventilated, and 18 patients (8%) had ventricular assist device support. Fifty-nine patients (25%) had hepatic dysfunction, and 15 patients (6%) had renal dysfunction. Twenty-one patients (9%) were dependent on total parenteral nutrition. Median postoperative stay was 24 (14-46) days, and in-hospital mortality was 7%. Kaplan-Meier analysis showed 1- and 5-year survivals of 89% (95% CI, 85-94) and 74% (95% CI, 81-86), respectively. Kaplan-Meier of Fontan patients without decompensation (n = 154) at transplant demonstrated 1- and 5-year survivals of 93% (95% CI, 88-97) and 88% (95% CI, 82-94), respectively. In-hospital mortality was higher in decompensated patients (11% vs 4%, P = .023). Multivariable analysis showed that decompensation predicted worse post-transplant survival (hazard ratio, 2.47; 95% CI, 1.16-5.22; P = .018), whereas older age at transplant predicted superior post-transplant survival (hazard ratio, 0.89/year; 95% CI, 0.80-0.98; P = .019).

CONCLUSIONS

Pediatric Fontan post-transplant outcomes are promising, although early mortality remains high. For nondecompensated pediatric patients at transplant without end-organ disease (>63% of cohort), early mortality is circumvented and post-transplant survival is excellent and similar to all pediatric transplantation.

Machine learning-based techniques to improve lung transplantation outcomes and complications: a systematic review

BACKGROUND

Machine learning has been used to develop predictive models to support clinicians in making better and more reliable decisions. The high volume of collected data in the lung transplant process makes it possible to extract hidden patterns by applying machine learning methods. Our study aims to investigate the application of machine learning methods in lung transplantation.

METHOD

A systematic search was conducted in five electronic databases from January 2000 to June 2022. Then, the title, abstracts, and full text of extracted articles were screened based on the PRISMA checklist. Then, eligible articles were selected according to inclusion criteria. The information regarding developed models was extracted from reviewed articles using a data extraction sheet.

RESULTS

Searches yielded 414 citations. Of them, 136 studies were excluded after the title and abstract screening. Finally, 16 articles were determined as eligible studies that met our inclusion criteria. The objectives of eligible articles are classified into eight main categories. The applied machine learning methods include the Support vector machine (SVM) (n = 5, 31.25%) technique, logistic regression (n = 4, 25%), Random Forests (RF) (n = 4, 25%), Bayesian network (BN) (n = 3, 18.75%), linear regression (LR) (n = 3, 18.75%), Decision Tree (DT) (n = 3, 18.75%), neural networks (n = 3, 18.75%), Markov Model (n = 1, 6.25%), KNN (n = 1, 6.25%), K-means (n = 1, 6.25%), Gradient Boosting trees (XGBoost) (n = 1, 6.25%), and Convolutional Neural Network (CNN) (n = 1, 6.25%). Most studies (n = 11) employed more than one machine learning technique or combination of different techniques to make their models. The data obtained from pulmonary function tests were the most used as input variables in predictive model development. Most studies (n = 10) used only post-transplant patient information to develop their models. Also, UNOS was recognized as the most desirable data source in the reviewed articles. In most cases, clinicians succeeded to predict acute diseases incidence after lung transplantation (n = 4) or estimate survival rate (n = 4) by developing machine learning models.

CONCLUSION

The outcomes of these developed prediction models could aid clinicians to make better and more reliable decisions by extracting new knowledge from the huge volume of lung transplantation data.

Not all durations of preheart transplant mechanical ventilation portend inferior post-transplant survival in children

BACKGROUND

Mechanical ventilation prior to pediatric heart transplantation predicts inferior post-transplant survival, but the impact of ventilation duration on survival is unclear.

METHODS

Data from the United Network for Organ Sharing and Pediatric Health Information System were used to identify pediatric (<18 years) heart transplant recipients from 2003 to 2020. Patients ventilated pretransplant were first compared to no ventilation, then ventilation durations were compared across quartiles of ventilation (≤1 week, 8 days-5 weeks, >5 weeks).

RESULTS

At transplant, 11% (511/4506) of patients required ventilation. Ventilated patients were younger, had more congenital heart disease, more urgent listing-status, and greater rates of nephropathy, TPN-dependence, and inotrope and ECMO requirements (p < .001 for all). Post-transplant, previously ventilated patients experienced longer ventilation durations, ICU and hospital stays, and inferior survival (all p < .001). Hospital outcomes and survival worsened with longer pretransplant ventilation. One-year and overall survival were similar between the no-ventilation and ≤1 week groups (p = .703 & p = .433, respectively) but were significantly worse for ventilation durations >1 week (p < .001). On multivariable analysis, ventilation ≤1 week did not predict mortality (HR 0.98 [95% CI 0.85-1.43]), whereas ventilation >1 week did (HR: 1.18 [1.01-1.39]).

CONCLUSIONS

Longer pretransplant ventilation portends worse outcomes, although only ventilation >1 week predicts mortality. These findings can inform pretransplant prognostication.

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.

Center Variability in Acute Rejection and Biliary Complications After Pediatric Liver Transplantation

Transplant center performance and practice variation for pediatric post-liver transplantation (LT) outcomes other than survival are understudied. This was a retrospective cohort study of pediatric LT recipients who received transplants between January 1, 2006, and May 31, 2017, using United Network for Organ Sharing (UNOS) data that were merged with the Pediatric Health Information System database. Center effects for the acute rejection rate at 1 year after LT (AR1) using UNOS coding and the biliary complication rate at 1 year after LT (BC1) using inpatient billing claims data were estimated by center-specific rescaled odds ratios that accounted for potential differences in recipient and donor characteristics. There were 2216 pediatric LT recipients at 24 freestanding children's hospitals in the United States during the study period. The median unadjusted center rate of AR1 was 36.92% (interquartile range [IQR], 22.36%-44.52%), whereas that of BC1 was 32.29% (IQR, 26.14%-40.44%). Accounting for recipient case mix and donor factors, 5/24 centers performed better than expected with regard to AR1, whereas 3/24 centers performed worse than expected. There was less heterogeneity across the center effects for BC1 than for AR1. There was no relationship observed between the center effects for AR1 or BC1 and center volume. Beyond recipient and allograft factors, differences in transplant center management are an important driver of center AR1 performance, and less so of BC1 performance. Further research is needed to identify the sources of variability so as to implement the most effective solutions to broadly enhance outcomes for pediatric LT recipients.

Children who stroke on VAD support: when is it safe to transplant and what are their outcomes?

OBJECTIVE

Ventricular assist devices (VADs) increase waitlist survival, yet the risk of stroke remains notable. The purpose of this study was to analyze how strokes on VAD support impact post-transplant (post-Tx) outcomes in children.

METHODS

520 pediatric (<18 yo) heart transplant candidates listed from January 2011 to April 2018 with a VAD implant date were matched between the United Network of Organ Sharing and Pediatric Health Information System databases. Patients were divided into pre-Tx Stroke and No Stroke cohorts.

RESULTS

81% of the 520 patients were transplanted. 28% (n=146) had a pre-Tx Stroke. 59% (n=89) of the Stroke patients were transplanted at a median of 57 (IQR 17-102) days from stroke. Significantly more No Stroke cohort (90%) were transplanted (p<0.001). There was no difference in post-Tx survival between the Stroke and No Stroke cohorts (p=0.440). Time between stroke and transplant for patients who died within one year of transplant was 32.0 days (median) compared to 60.5 days for those alive > 1year (p=0.18). Regarding patients in whom time from stroke to transplant was more than 60 days, one-year survival of Stroke vs. No Stroke patients was 96% vs. 95% (p=0.811), respectively.

CONCLUSION

Patients with stroke during VAD support, once transplanted, enjoy similar survival compared to No Stroke patients. We hypothesize that allowing Stroke patients more time to recover could improve post-Tx outcomes. Unfortunately, the ideal duration of time between stroke and safe transplantation could not be determined and will require more detailed and larger studies in the future.

Demographics and Risk Factors of Pediatric Pulmonary Hypertension Readmissions

BACKGROUND AND OBJECTIVES

Pulmonary hypertension (PH) leads to significant morbidity and mortality in pediatric patients and increases the readmission rates for hospitalizations. This study evaluates the risk factors and comorbidities associated with an increase in 30-day readmissions among pediatric PH patients.

METHODS

National Readmission Database (NRD) 2017 was searched for patients less than 18 years of age who were diagnosed with PH based on the International Classification of Diseases, 10th Revision (ICD-10). Statistical Package for the Social Sciences (SPSS) software v25.0 (IBM Corp., Armonk, NY) was used for statistical analysis.

RESULTS

Of 5.52 million pediatric encounters, 10,501 patients met the selection criteria. The 30-day readmission rate of 14.43% (p < 0.001) was higher than hospitalizations from other causes {Odds Ratio (OR) 4.02 (3.84-4.20), p < 0.001}. The comorbidities of sepsis {OR 0.75 (0.64-0.89), p < 0.02} and respiratory infections {OR 0.75 (0.67-0.85), p < 0.001} were observed to be associated with lower 30-day readmissions. Patients who required invasive mechanical ventilation via endotracheal tube {OR 1.66 (1.4-1.96), p < 0.001} or tracheostomy tube {OR 1.35 (1.15-1.6), p < 0.001} had increased unplanned readmissions. Patients with higher severity of illness based on All Patients Refined Diagnosis Related Groups (APR-DRG) were more likely to get readmitted {OR 7.66 (3.13-18.76), p < 0.001}.

CONCLUSION

PH was associated with increased readmission rates compared to the other pediatric diagnoses, but the readmission rate in this study was lower than one previous pediatric study. Invasive mechanical ventilation, Medicaid insurance, higher severity of illness, and female gender were associated with a higher likelihood of readmission within 30 days.

Transplantation for Congenital Heart Disease: Focus on the Impact of Functionally Univentricular Versus Biventricular Circulation

BACKGROUND

Varying single center data exist regarding the posttransplant outcomes of patients with single ventricle circulation, particularly following the Fontan operation. We sought to better elucidate these results in patients with congenital heart disease (CHD) through combining two national databases.

METHODS

The United Network for Organ Sharing (UNOS) transplantation database was merged with the Pediatric Health Information System (PHIS), an administrative database with 71% of UNOS patients matched. Patients undergoing transplantation at a PHIS hospital from 2006 to 2017 were categorized as single ventricle or biventricular strategy based on their diagnoses and procedures in 90% of patients. When known, single ventricle patients were further analyzed by their palliative stage post-Glenn or post-Fontan (known in 31%).

RESULTS

A total of 1,517 CHD transplantations were identified, 67% with single ventricle strategy (1,016). Single ventricle, biventricular, and indeterminate patients had similar survival (log-rank P > .1). Risk factors for mortality in patients with CHD were extracorporeal membrane oxygenation (ECMO) support at transplant (hazard: 2.27), ABO blood type incompatibility (hazard: 1.61), African American recipient (hazard 1.42), and liver dysfunction (hazard 1.29). A total of 130 confirmed Fontan and 185 confirmed bidirectional Glenn patients underwent transplantation, each with survival equivalent to biventricular patients (log-rank P > .500). For Fontan patients, renal dysfunction (hazard: 5.40) and transplant <1 year after Fontan (hazard 2.82) were found to be associated with mortality.

CONCLUSIONS

Single ventricle patients, as a group, experience similar outcomes as biventricular patients with CHD undergoing transplantation, and this extends to Fontan patients. Risk factors for mortality correlate with end-organ dysfunction as well as race and ABO blood type incompatibility in the CHD population.

Validation of the american quality assessment model and performance improvement to the brazilian transplant

Objective:

To validate the quality assessment and performance improvement instrument of US transplant programs to the Brazilian reality.

Method:

Methodological study developed for semantic validation and cultural adaptation of the Quality assessment and Performance Improvement instrument in the following steps: 1) translation; 2) synthesis; 3) back translation; 4) review by expert committee; 5) pretest and 6) content validation. To evaluate the agreement between the five judges, the Kappa coefficient was used and for content validation, the content validation index.

Results:

Kappa coefficient showed the agreement of the judges for semantic, idiomatic, cultural and conceptual equivalences. Content validation index values for relevance and item sequence of at least 0.80 for all blocks.

Conclusion:

The instrument of Quality Evaluation and Performance Improvement of Transplantation Programs proved to be valid and reliable. This instrument will contribute to the development of quality assurance programs for transplant teams in Brazil.

Expanding analytic possibilities in pediatric solid organ transplantation through linkage of administrative and clinical registry databases

Database linkage is a common strategy to expand analytic possibilities. Our group recently completed a linkage between the SRTR and PHIS databases for pediatric heart transplant recipients. The aim of this project was to expand the linkage between SRTR and PHIS to include liver, kidney, lung, heart-lung, and small bowel transplants. All patients (<21 years) who underwent liver, kidney, lung, heart-lung, or small bowel transplant were identified from the PHIS database using APR-DRG codes (2002-2018). Linkage was performed in a stepwise approach using indirect identifiers. Hospital costs were estimated based on hospital charges and cost-to-charge ratios, inflated to 2018 dollars and described by transplant type. A total of 14 061 patients overlapped between databases. Of these, 13 388 (95.2%) were uniquely linked. Linkage success ranged from 92.6% to 97.8% by organ system. A total of 12 940 (92%) patients had complete cost data. Hospitalization costs were greatest for patients undergoing small bowel transplantation with a median cost of $734 454 (IQR $336 174 - $1 504 167), followed by heart $565 386 (IQR $352 813 - $999 216), heart-lung $471 573 (IQR $328 523 - 992 438), lung $303 536 (IQR $215 383 - $612 749), liver $200 448 (IQR $130 880 - $357 897), and kidney transplant $94 796 (IQR $73 157 -$131 040). We report a robust linkage between the SRTR and PHIS databases, providing an invaluable tool to assess resource utilization in solid organ transplant recipients. Our analysis provides contemporary cost data for pediatric solid organ transplantation from the largest US sample reported to date. It also provides a platform for expanded analyses in the pediatric transplant population.