Pediatric Risk to Orthotopic Heart Transplant (PRO) Score: Insights from United Network for Organ Sharing (UNOS) Waitlist Mortality Findings

BackgroundPediatric heart transplant candidates on the waitlist have the highest mortality rate among all solid organ transplants. A risk score incorporating a candidate's individual risk factors may better predict mortality on the waitlist and optimize organ allocation to the sickest of those awaiting transplant. MethodsUsing the United Network for Organ Sharing (UNOS) database, we evaluated a total of 5542 patients aged 0-18 years old on the waitlist for a single, first time, heart transplant from January 2010 to June 2019. We performed a univariate analysis on two-thirds (N = 3705) of these patients to derive the factors most associated with waitlist mortality or delisting secondary to deterioration within 1 year. Those with a p <0.2 underwent a multivariate analysis and the resulting factors were used to build a prediction model using the Fine-Grey model analysis. This predictive scoring model was then validated on the remaining one-third of the patients (N = 1852). ResultsThe Pediatric Risk to OHT (PRO) scoring model utilizes the following unique patient variables: blood type, diagnosis of congenital heart disease, weight, presence of ventilator support, presence of inotropic support, extracorporeal membrane oxygenation (ecmo) status, creatinine level, and region. A higher score indicates an increased risk of mortality. The PRO score had a predictive strength of 0.762 as measured by area under the ROC curve at 1 year. ConclusionThe PRO score is an improved predictive model with the potential to better assess mortality for patients awaiting heart transplant.