Waitlist Mortality for Children Listed for Heart Transplant in the United States: How are We Doing?

Abstract

PurposeStudies suggest that pediatric heart transplant (HT) waitlist mortality has declined. The impact of factors like refinements to the heart allocation system, patient selection, greater ABO incompatible (ABO-I) HT and VAD support are unknown. We examined the 20-year trend in waitlist mortality to identify factors associated with declining mortality and whether allocational inefficiencies persist.MethodsAll children <18 years listed for isolated HT from 1999-2020 were identified using OPTN data and grouped into 3 eras (Era 1: 1999-2006; Era 2: 2006-2016; Era 3: 2016-2020) based on when UNOS revised the heart allocation system. Cox proportional hazards modeling was used to identify factors associated with death or delisting due to deterioration.ResultsOverall 11,374 patients met inclusion criteria (3,248 in Era 1; 5,378 in Era 2; 2,748 in Era 3). Waitlist mortality declined significantly across eras (21%, 17%, 13%, P<0.001). The prevalence at listing of major risk factors for mortality declined across eras including a reduction by 47% in ECMO use (11% to 6%, P<0.001), 33% in ventilator use (27% to 18%, P<0.001), 26% in dialysis use (2.5% to 1.8%, P=0.08); in contrast VAD use at listing increased by 243% (6% to 15%, P<0.001). Infant mortality declined significantly (27% to 20%, P<0.001) with a 48% decline in mortality for blood group O patients (relative to the background decline for all blood groups) and a 69% decline in infant VAD mortality (P<0.01). In Era 3, RCM and re-transplant patients not eligible for status 1A without exception had higher mortality than 1A DCM patients on LVAD support (16% vs 5.3%, P<0.01).ConclusionPediatric HT waitlist mortality has declined significantly over the past 20 years. There is evidence to suggest that greater VAD use, revisions to organ allocation, refinements in patient selection and ABO-I transplant may all contribute. Organ allocation inefficiencies persist under the current allocation system suggesting opportunities for allocation improvement may still exist. Studies suggest that pediatric heart transplant (HT) waitlist mortality has declined. The impact of factors like refinements to the heart allocation system, patient selection, greater ABO incompatible (ABO-I) HT and VAD support are unknown. We examined the 20-year trend in waitlist mortality to identify factors associated with declining mortality and whether allocational inefficiencies persist. All children <18 years listed for isolated HT from 1999-2020 were identified using OPTN data and grouped into 3 eras (Era 1: 1999-2006; Era 2: 2006-2016; Era 3: 2016-2020) based on when UNOS revised the heart allocation system. Cox proportional hazards modeling was used to identify factors associated with death or delisting due to deterioration. Overall 11,374 patients met inclusion criteria (3,248 in Era 1; 5,378 in Era 2; 2,748 in Era 3). Waitlist mortality declined significantly across eras (21%, 17%, 13%, P<0.001). The prevalence at listing of major risk factors for mortality declined across eras including a reduction by 47% in ECMO use (11% to 6%, P<0.001), 33% in ventilator use (27% to 18%, P<0.001), 26% in dialysis use (2.5% to 1.8%, P=0.08); in contrast VAD use at listing increased by 243% (6% to 15%, P<0.001). Infant mortality declined significantly (27% to 20%, P<0.001) with a 48% decline in mortality for blood group O patients (relative to the background decline for all blood groups) and a 69% decline in infant VAD mortality (P<0.01). In Era 3, RCM and re-transplant patients not eligible for status 1A without exception had higher mortality than 1A DCM patients on LVAD support (16% vs 5.3%, P<0.01). Pediatric HT waitlist mortality has declined significantly over the past 20 years. There is evidence to suggest that greater VAD use, revisions to organ allocation, refinements in patient selection and ABO-I transplant may all contribute. Organ allocation inefficiencies persist under the current allocation system suggesting opportunities for allocation improvement may still exist.