Variation in Heart-Transplant Rates Remains Despite Change in Allocation Policy

By Megan Brooks

January 20, 2022

NEW YORK (Reuters Health) - Despite the recent change in heart-allocation policy designed to boost equitable distribution of the limited number of available organs, substantial center-level and regional variation in likelihood of transplant remains, according to a new analysis.

"Wide state-level variability in waiting list outcomes have been noted for patients listed for heart transplant in the U.S., but little is known regarding center-level transplant rates since the heart allocation policy change," the study team notes in JAMA Cardiology.

"The new heart-allocation policy enacted in 2018 aimed to provide organs for the most critically ill. By definition then, those whose lives were not immediately at risk were deprioritized," Dr. Peyman Benharash of the David Geffen School of Medicine at the University of California, Los Angeles, told Reuters Health by email.

As part of the policy change, patients requiring temporary mechanical circulatory support (tMCS) devices such as extracorporeal membrane oxygenation (ECMO), percutaneous ventricular-assist devices (pVADs) and intraaortic balloon pumps (IABP) were prioritized, whereas those with durable left ventricular-assist devices (LVADs) received lower priority.

"We wondered if transplant centers perform differently under the new policy (and) were surprised to find such variation in waitlist outcomes," Dr. Benharash said.

The study team analyzed data from the United Network for Organ Sharing (UNOS) database from 2015 to 2020. This period was chosen to allow for adequate follow-up time before and after the policy revision and before COVID-19 affected transplant practices.

Heart-transplant candidates were stratified into two time periods, the first encompassing the three-year period before the UNOS allocation-policy change (10,877 candidates) and the second representing the 500-day period after the policy change but before the start of the pandemic (5,063 candidates).

The team observed that the number of patients with tMCS (a priority group under the policy change) increased between the first and second periods (ECMO from 2.00% to 3.42%; pVAD from 0.66% to 1.86%; and IABP from 5.21% to 13.10%).

"Patients treated at centers that used mechanical circulatory support more often were more likely to receive a heart transplant; identification of variation is generally considered the first step in quality-improvement efforts," Dr. Benharash commented.

"While patient factors may certainly play a role, our findings suggest the presence of practitioner and center-level variation. Thus, guidelines that homogenize practice may be beneficial in achieving more equitable care," the researcher added.

The study team also observed that overall adjusted transplant rates increased following the change in heart-allocation policy: from 48.1% in the first period to 78.0% in second.

However, significant variation was observed among centers within the same region and those sharing the same organ supply. The largest absolute difference in transplant rates was 27.1 percentage points for two centers belonging to the same organ-procurement organization. Higher center volume and IABP use were associated with greater center-level transplant rates.

"To our knowledge, the present study is the first to report significant variation in center-level likelihood of heart transplant. Further studies and policies are likely needed to ensure equitable allocation in heart transplantation," the study team concludes.

SOURCE: JAMA Cardiology, online January 19, 2022.