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Transplant Center and Survival Benefit of Heart Transplant Patients
Study Questions:
Is there an association between transplant center and survival benefit in the US heart allocation system?
Methods:
This was an observational study of 29,199 adult candidates for heart transplant (HT) listed on the national transplant registry from January 2006–December 2015. The survival benefit associated with HT was defined by the difference between survival after HT and waiting list survival without transplant at 5 years. The study authors estimated each transplant center’s mean survival benefit utilizing a mixed-effects proportional hazards model with transplant as a time-dependent covariate, adjusted for year of transplant, donor quality, ischemic time, and candidate status. The primary outcome was the survival benefit associated with HT as quantified by the estimated improvement in absolute 5-year survival gained by undergoing HT. Secondary outcomes were the characteristics of patients who received transplants at high versus low survival benefit centers, including status and the proportion of recipients treated with status 1A–qualifying intra-aortic balloon pumps or high-dose inotropes but who did not meet the hemodynamic requirements for cardiogenic shock.
Results:
The mean age of the cohort was 52 years and 26% were women on the transplant waiting list at 113 centers; 68% (n = 19,815/29,199) underwent HT. Among HT recipients, 27% (n = 5,389) died or underwent another transplant operation during the study period. Of the 9,384 candidates who did not undergo HT, 60% (n = 5,669) died (2,644 while on the waiting list and 3,025 after being delisted). The estimated 5-year survival was 77% (interquartile range [IQR], 74%-80%) among transplant recipients and 33% (IQR, 17%-51%) among those who did not undergo HT, which is a survival benefit of 44% (IQR, 27%-59%). Survival benefit ranged from 30% to 55% across centers and 31 centers (27%) had significantly higher survival benefit than the mean and 30 centers (27%) had significantly lower survival benefit than the mean. Compared with low survival benefit centers, high survival benefit centers performed HT for patients with lower estimated expected waiting list survival without transplant (29% at high survival benefit centers vs. 39% at low survival benefit centers; survival difference, −10% [95% CI, −12% to −8.1%]), although the adjusted 5-year survival after transplant was not significantly different between high and low survival benefit centers (77.6% vs. 77.1%, respectively; survival difference, 0.5% [95% CI, −1.3% to 2.3%]). Overall, for every 10% decrease in estimated transplant candidate waiting list survival at a given center, there was an increase of 6.2% (95% CI, 5.2%–7.3%) in the 5-year survival benefit associated with heart transplant.
Conclusions:
The authors concluded that in this registry-based study of HT candidates, the transplant center was associated with the survival benefit of transplant. Although the adjusted 5-year survival after transplant was not significantly different between high and low survival benefit centers, compared with centers with survival benefit significantly below the mean, centers with survival benefit significantly above the mean performed HT for recipients who had significantly lower estimated expected 5-year waiting list survival without transplant.
Perspective:
In their discussion, the authors suggest that for specific management practices at centers with lower survival, these centers are more likely to select stable candidates and escalate supportive therapies as needed to achieve status 1A. Low survival benefit centers frequently treated candidates with high-dose inotropes and intra-aortic balloon pumps despite the absence of cardiogenic shock. Low survival benefit centers also used the device-related complication indication for candidates with left ventricular assist device (LVAD) implants (who have low medical urgency without transplant). The new six-tier allocation system was associated with less variation in survival benefit across centers, potentially through the limited incorporation of objective medical acuity criteria and disease-specific status adjustments. However, there is room for improvement—the allocation system may have to be updated to properly account for LVAD implant support and to maximize the survival benefit gains from HT.
Keywords: Cardiac Surgical Procedures, Graft Survival, Heart-Assist Devices, Heart Failure, Heart Transplantation, Hemodynamics, Intra-Aortic Balloon Pumping, Shock, Cardiogenic, Survival Rate, Tissue Donors
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