Abstract and Introduction
Abstract
We describe waiting times for pediatric heart transplant (HT) candidates after the 2016 revision to the US allocation policy. The OPTN database was queried for pediatric HT candidates listed between 7/2016 and 4/2019. Of the 1789 included candidates, 65% underwent HT, 14% died/deteriorated, 8% were removed for improvement, and 13% were still waiting at the end of follow-up. Most candidates were status 1A at HT (81%). Median wait times differ substantially by listing status, blood type, and recipient weight. The likelihood of HT was lower in candidates <25 kg and in those with blood type O; The <25 kg, blood type O subgroup experiences longer wait times and higher wait list mortality. For status 1A candidates, median wait times were 108 days (≤25 kg, blood type O), 80 days (≤25 kg, non-O), 47 days (>25 kg, O), and 24 days (>25 kg, non-O). We found that centers with more selective organ acceptance practices, based on a lower median Pediatric Heart Donor Assessment Tool (PH-DAT) score for completed transplants, experience longer status 1A wait times for their listed patients. These data can be used to counsel families and to select appropriate advanced heart failure therapies to support patients to transplant.
Introduction
Heart transplantation (HT) is a lifesaving therapy for children with end stage heart failure. However, children waiting for HT experience the highest waitlist mortality of all pediatric organ transplant candidates.[1,2] Given the difficulty in supporting children with end stage heart failure to HT, it is important for pediatric cardiologists to understand the range of expected HT wait times to provide appropriate medical and surgical therapies to support the listed patient. The pediatric heart allocation policy was last revised in 2016 and resulted in a small decrease in the number of children listed at the highest urgency status.[3] While the Scientific Registry of Transplant Recipients (SRTR) reports national pediatric HT rates per 100 person-years waiting in their annual report and a deceased donor transplant rate ratio estimate in their program specific reports, this data does not provide information in a manner that is easily understood by patients and families.
In accordance with the Organ Procurement and Transplantation Network (OPTN) Final Rule, one primary goal of heart allocation policy is to allocate donor hearts based on medical urgency.[3] US pediatric heart allocation follows an algorithm that prioritizes candidates based on three tiers of medical urgency (UNOS Status 1A, 1B, 2), blood type, and distance between the donor and recipient hospitals. The pediatric status 1A tier includes a highly heterogeneous group of patients ranging from those who are stable on inotropes to children on ECMO support.[1,4] The most recent modification to the pediatric heart allocation policy was enacted in 2016. Specific changes included: (1) reduced priority for candidates with cardiomyopathy, (2) requirement for hospital admission of candidates with “significant” congenital heart disease on high-dose inotropes to qualify for status 1A listing, and (3) removal of in utero listing mechanisms. There are limited data on wait list outcomes under this new allocation policy.[4] We therefore sought to describe the range of expected wait times under the current allocation system. We hypothesized that children weighing less than 25 kg represent a unique population with prolonged wait times relative to larger children.