A study from cardiologists at UPMC Children's Hospital of Pittsburgh examining changes to criteria in 2016, which aimed to improve mortality rates among pediatric candidates for heart transplantation, found rates have worsened for certain conditions.
Despite recent revisions to Organ Procurement and Transplantation Network criteria, a new study from the University of Pittsburgh Medical Center (UPMC) has found these revisions have resulted in no overall improvement in waitlist mortality rates in children awaiting heart transplantation may have worsened pediatric mortality rates for certain types of cardiovascular disease.
The study examined the impact of the March 2016 revision to Organ Procurement and Transplantation Network criteria for prioritizing children awaiting heart transplants. It revealed revisions not only led to no overall improvement, but may have worsened mortality for some forms of cardiovascular disease.
"We can't prove causality here, but it would seem that restrictive and hypertrophic cardiomyopathy patients have been disadvantaged by the criteria change," said lead investigator Brian Feingold, MD, medical director of pediatric heart failure and heart transplantation at UPMC Children's Hospital of Pittsburgh. "They're prioritized downward under the umbrella of cardiomyopathy, likely inadvertently, while children with congenital heart defects have not been able to benefit due to increased exception use."
In an effort to assess the impact of the 2016 revisions—which deprioritized candidates with cardiomyopathy while maintaining status 1A eligibility for congenital heart disease candidates on high-dose inotropes—investigators designed a study that compared waitlist characteristics and mortality rates surrounding the change.
Using Organ Procurement and Transplantation Network database information, investigators identified patients less than 18 years old, who had been listed for isolated heart transplantation, from December 16, 2011 to June 30, 2018.
Investigators assessed patient information including age, weight, sex, race, waitlist urgency status, underlying cardiac diagnosis, level of intravenous inotropic support and use of ventricular assist device, extracorporeal membrane oxygenation, mechanical ventilation, and inhaled nitric oxide.
They calculated total waitlist days from list and delisting, transplant, or censoring dates. Waitlist mortality was calculated using the composite endpoint of death on the waitlist or delisting due to clinical deterioration—the status 1A exceptions were quantified and stratified by era and diagnosis.
Upon analyses, investigators found that status 1A listing decreased from 70% to 56% (P <.001). The rate of congenital heart disease among status 1A listings increased from 48% to 64% (P <.001).
Investigators noted the overall waitlist mortality (subdistribution hazard ratio (SHR) 0.96, P=0.63) and mortality among status 1A candidates (SHR 1.16, P = .14) remained unchanged during the study period. Rates for congenital heart disease trended better (SHR 0.82, P = .06), but was unchanged among congenital heart disease patients listed status 1A (SHR 0.92, P = .47).
Additionally, status 1A listing exception increased 2- to 3-fold among hypertrophic and restrictive cardiomyopathy candidates and 13.5-fold among dilated cardiomyopathy candidates. Investigators noted increased waitlist mortality among hypertrophic (SHR 6.25, P = .004) and restrictive cardiomyopathy (SHR 3.87, P = .03) candidates without status 1A exception, while those with dilated cardiomyopathy did not (SHR 1.26, P = .32).
Ventricular assist device use was only associated with increased use among dilated cardiomyopathy patients aged 1 year or older (26% vs 38%, P <.001).
"Changes were made to prioritize sicker children with fewer treatment options—for instance, kids with congenital heart defects,” Feingold said. “But the reality we're showing is that since the criteria change, transplant centers are using more listing status exceptions, essentially short-circuiting the intended benefit.”
This study, “Impact of the 2016 revision of US pediatric heart allocation policy on waitlist characteristics and outcomes,” was published online in the American Journal of Transplantation.