Heart Transplant 'Survival Benefit' Varies by Transplant Center

Megan Brooks

November 13, 2019

A new analysis suggests the 5-year "survival benefit" for heart transplant recipients in the US varies across transplant centers, with "high" survival benefit centers performing heart transplant for sicker patients with lower estimated waiting list survival without a transplant.

"Hearts are scarce and hundreds of patients die on the wait list each year, so giving hearts to the sickest candidates is very important and mandated by federal regulations," first author William F. Parker, MD, instructor, pulmonary and critical care medicine, University of Chicago, Illinois, told theheart.org | Medscape Cardiology.

Parker and colleagues quantified the national variation in heart transplant survival benefit, which is how much patient survival was improved by receiving a heart transplant.

"While all centers achieve about the same posttransplant survival, certain centers are transplanting much sicker candidates than others. These 'high benefit' centers are effectively saving more lives with the scarce resource than the low benefit centers," said Parker.

The study was published online November 12 in JAMA.

Interpret Cautiously

In an editorial accompanying the study, Alexander Sandhu, MD, and coauthors from Stanford University in California caution that the survival benefit metric, as calculated, can be challenging to interpret at the center level.

"For example, there may be differences between centers in quality of care prior to transplant. Centers with high-quality care prior to transplant may have lower waiting list mortality and therefore lower survival benefit," they write. "If variation in care prior to transplant were a major driver of differences in survival benefit, the survival benefit metric would inappropriately penalize high-quality centers."

"Equally concerning," write Sandhu and colleagues, is that the differences in how centers prioritize patients for transplant can affect the calculated survival benefit.

"Centers that perform heart transplant for patients with high disease severity will reduce their waiting list mortality, but may have higher mortality after transplant. This will reduce the difference between waiting list and post-transplant mortality," they explain.

"On the other hand, a more conservative transplant program that removes patients with the highest disease severity from active consideration for transplant will have higher waiting list mortality and lower posttransplant mortality," they add. "Thus, comparing survival benefit across centers becomes challenging without adjustment for detailed patient-level disease severity."  

Summing up, the editorialists note that "suboptimal use of organs and barriers to patient access continue to limit the potential benefit of transplant on heart failure outcomes nationally. The transplant community owes it to donors and their families to continually improve the organ allocation system to ensure that society is deriving the maximum good from their precious gift of life."

Center-Specific Survival

The registry-based observational study included 29,199 adult candidates listed for a heart-only transplant at one of 113 centers in the US from 2006 to 2015. Two thirds (19,815, 68%) received a heart transplant.

The researchers modeled center-specific survival benefit (defined as the difference in 5-year survival between patients who underwent heart transplant and those on the waiting list) using a mixed-effects survival model adjusted for listing status, year, and donor risk factors.

Among patients who received a heart transplant, 5389 (27%) died or underwent another transplant operation during the study period. Of the 9384 candidates who did not undergo heart transplant, 5669 (60%) died — 2644 (47%) while on the waiting list and 3025 (53%) after coming off the waiting list.

The estimated 5-year survival was 77% among transplant recipients versus 33% among those who did not undergo heart transplant — a survival benefit of 44% (interquartile range, 27% to 59%).

The survival benefit associated with heart transplant ranged from 30% to 55% across centers; 31 centers (27%) had significantly higher survival benefit than the average, while 30 centers (27%) had significantly lower survival benefit than the average.

High survival benefit transplant centers performed heart transplants for more patients with lower estimated expected waiting list survival without transplant compared with low survival benefit centers (29% vs. 39%).

"High survival benefit centers had an estimated absolute 5-year survival benefit that was 10.6% higher than low survival benefit centers by achieving good posttransplant outcomes for patients with lower cardiac indices, higher pulmonary capillary wedge pressures, worse functional status, and lower estimated candidate waiting list 5-year survival," the researchers write.

However, there was no significant difference in adjusted 5-year survival after transplant between high and low survival benefit centers (77.6% vs 77.1%).

In an exploratory analysis, the researchers retrospectively reclassified patients according to the new 6-tier heart allocation system introduced in October 2018. Although limited by the imprecision of reclassification, this analysis showed that the new 6-tier allocation system was associated with less variation in survival benefit across centers.

"The 6-tier system has the potential to improve heart allocation by more accurately identifying and prioritizing the sickest candidates. However, we found that there is still room for improvement (as shown by significant between-center variation in survival benefit even with the 6-tiers)," Parker told theheart.org | Medscape Cardiology.

"Furthermore, the new system is still fundamentally therapy-based, so any improvement is contingent upon transplant centers not changing practices in response to the new rules. I think it's likely that the transplant centers will respond to the new criteria and change practices to get their patients the highest priority status they can," Parker said.

The study was supported by the National Heart, Lung, and Blood Institute; the National Institutes of Health; and the National Institute of General Medical Sciences. Parker and the editorial writers have disclosed no relevant financial relationships.

JAMA. Published November 12, 2019. Full text, Editorial

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