Agreement between risk and priority for heart transplant: Effects of the geographic allocation rule and status assignment

Survival After Simultaneous Heart-kidney Transplant in Recipients With a Durable LVAD and Chronic Kidney Disease: Effect of the 2018 Heart Allocation Policy Change

BACKGROUND

Heart transplantation remains the most definitive therapy for qualified candidates with end-stage heart failure. Concomitant kidney disease is common in this population prompting an increase in simultaneous heart-kidney (SHK) transplantation in recent years. The goal of our study was to explore the effects of the 2018 heart allocation policy (HAP) change on candidate listing characteristics and compare survival rates at 1 y in patients that were supported with a left ventricular assist device (LVAD) pretransplant and underwent SHK or heart alone transplant (HAT).

METHODS

We used data from the Scientific Registry of Transplant Recipients and identified all adults who underwent primary SHK or HAT between January 2010 and March 2022. Recipients supported with a durable LVAD and estimated glomerular filtration rate <60 mL/min/1.73 m 2 were selected (n = 309 SHK; 217 pre- and 92 post-HAP and n = 3,324 HAT; 2738 pre- and 586 post-HAP).

RESULTS

Difference in survival at 1 y did not reach statistical significance. Comparing the 1-y survival of SHK and HAT recipients who were bridged with LVAD pre-HAP, we found no significant difference ( P = 0.694). Adjusting for the same covariates in a multivariable model did not affect the results (SHK versus HAT hazard ratio 0.84 [0.51, 1.37]; P = 0.48). In contrast, SHK recipients supported with an LVAD who were listed and transplanted post-HAP change had significantly lower 1-y survival, when compared with HAT ( P = 0.037).

CONCLUSIONS

Our findings suggest that the HAP change had a potentially negative impact on the survival of select patients undergoing SHK transplant. Further research is warranted in this area.

Temporary Mechanical Circulatory Support Use and Clinical Outcomes of Simultaneous Heart/Kidney Transplant Recipients in the Pre- and Post-heart Allocation Policy Change Eras

BACKGROUND

The use of temporary mechanical circulatory support (tMCS) devices (intra-aortic balloon pump; Impella 2.5, CP, 5.0; venoarterial extracorporeal membrane oxygenation) increased significantly across the United States for heart transplant candidates after the allocation policy change. Whether this practice change also affected simultaneous heart-kidney (SHK) candidates and recipient survival is understudied.

METHODS

We used the Scientific Registry of Transplant Recipients database to identify adult SHK recipients between January 2010 and March 2022. The population was stratified into pre- and post-heart allocation change cohorts. Kaplan-Meier curves were generated to compare 1-y survival rates. A Cox proportional hazards model was used to investigate the effect of allocation period on patient survival. Recipient outcomes bridged with eligible tMCS devices were compared in the post-heart allocation era. In a separate analysis, SHK waitlist mortality was evaluated between the allocation eras.

RESULTS

A total of 1548 SHK recipients were identified, and 1102 were included in the final cohort (534 pre-allocation and 568 post-allocation change). tMCS utilization increased from 17.9% to 51.6% after the allocation change, with venoarterial extracorporeal membrane oxygenation use rising most significantly. However, 1-y post-SHK survival remained unchanged in the full cohort (log-rank P  = 0.154) and those supported with any of the eligible tMCS devices. In a separate analysis (using a larger cohort of all SHK listings), SHK waitlist mortality at 1 y was significantly lower in the current allocation era ( P  = 0.002).

CONCLUSIONS

Despite the remarkable increase in tMCS use in SHK candidates after the heart allocation change, 1 y posttransplant survival remained unchanged. Further studies with larger cohorts and longer follow-ups are needed to confirm these findings.

Allocation changes in heart transplantation: What has really changed?

OBJECTIVE

In 2018, the heart allocation system changed status classifications and broadened geographic distribution. We examined this change at a national level based on the immediate pre- and postchange periods.

METHODS

Using the Scientific Registry of Transplant Recipients database, we identified all adult primary, isolated heart transplants from October 18, 2017, to October 17, 2019. Two time periods were compared: (1) October 18, 2017, to October 17, 2018 (pre); and (2) October 18, 2018, to October 17, 2019 (post). Comparisons were made between groups, and a multivariable logistic regression model was created to identify factors associated with pretransplant temporary mechanical circulatory support. Volume analysis at the regional, state, and center level was also conducted as the primary focus.

RESULTS

A total of 5381 independent heart transplants were identified within the time frame. On unadjusted analysis, there was a significant increase in temporary mechanical circulatory support (pre, 11.1%; post, 36.2%, P < .01) and decrease in waitlist days (pre, 93 days; post, 41 days; P < .01). Distance traveled (nautical miles) (pre, 83; post, 225; P < .01) and ischemic time (hours) (pre, 3.0; post, 3.4; P < .01) were significantly increased. On multivariable analysis, the postallocation time period was independently associated with temporary MCS (odds ratio, 4.463; 95% confidence interval, 3.844-5.183; P < .001). Transplant volumes did not significantly change after the allocation change at a regional, state, and center level.

CONCLUSIONS

Since the planned alteration to the allocation system, there have been changes in the use of temporary mechanical circulatory support as well as distance and ischemic time associated with transplant, but no significant volume changes were observed. Continued observation of outcomes and volume under the new allocation system will be necessary in the upcoming years.

Association of Transplant Center With Survival Benefit Among Adults Undergoing Heart Transplant in the United States

IMPORTANCE

In the United States, the number of deceased donor hearts available for transplant is limited. As a proxy for medical urgency, the US heart allocation system ranks heart transplant candidates largely according to the supportive therapy prescribed by transplant centers.

OBJECTIVE

To determine if there is a significant association between transplant center and survival benefit in the US heart allocation system.

DESIGN, SETTING, AND PARTICIPANTS

Observational study of 29 199 adult candidates for heart transplant listed on the national transplant registry from January 2006 through December 2015 with follow-up complete through August 2018.

EXPOSURES

Transplant center.

MAIN OUTCOMES AND MEASURES

The survival benefit associated with heart transplant as defined by the difference between survival after heart transplant and waiting list survival without transplant at 5 years. Each transplant center's mean survival benefit was estimated using 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.

RESULTS

Of 29 199 candidates (mean age, 52 years; 26% women) on the transplant waiting list at 113 centers, 19 815 (68%) underwent heart transplant. Among heart transplant recipients, 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 while on the waiting list and 3025 after being delisted). Estimated 5-year survival was 77% (interquartile range [IQR], 74% to 80%) among transplant recipients and 33% (IQR, 17% to 51%) among those who did not undergo heart transplant, which is a survival benefit of 44% (IQR, 27% to 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 heart transplant 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% to 7.3%) in the 5-year survival benefit associated with heart transplant.

CONCLUSIONS AND RELEVANCE

In this registry-based study of US heart transplant candidates, 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 heart transplant for recipients who had significantly lower estimated expected 5-year waiting list survival without transplant.

Assessing the outcome of organ allocation: choosing metrics

PURPOSE OF REVIEW

Organ allocation is a highly complex process with significant impact on outcomes of donor organs and end-stage organ disease patients. Policies governing allocation must incorporate numerous factors to meet stated objective. There have been significant alterations and ongoing discussion about changes in allocation policy for all solid organs in the United States. As with any policy change, rigorous evaluation of the impact of changes is important.

RECENT FINDINGS

This manuscript discusses metrics to consider to evaluate the impact of organ allocation policy that may be monitored on an ongoing basis including examples of research evaluating current policies. Potential metrics to evaluate allocation policy include the effectiveness, efficiency, equity, costs, donor rates, and transparency associated with the system.

SUMMARY

Ultimately, policies will often need to adapt to secular changes in donor and patient characteristics, clinical and technological advances, and overarching healthcare polices. Providing objective empirical evaluation of the impact of policies is a critical component for assessing quality of the allocation system and informing the effect of changes. The foundation of organ transplantation is built upon public trust and the dependence on the gift of donor organs, as such the importance of the most appropriate organ allocation policies cannot be overstated.

Contemporary Issues in Lung Transplant Allocation Practices

PURPOSE OF REVIEW

To discuss the current state of donor lung allocation in the United States, and future opportunities to increase the efficiency of donor lung allocation.

RECENT FINDINGS

The current donor lung allocation system prioritizes clinical acuity by use of the Lung Allocation Score (LAS) which has reduced waitlist mortality since its implementation in 2005. Access to donor lungs can be further improved through policy changes using broader geographic sharing, and developing new technology such as ex vivo lung perfusion to recover marginal donor lungs.

SUMMARY

The number of lung transplants in the U.S. continues to increase annually. However, the demand for donor lungs continues to be outpaced by an ever growing waitlist. Efficient allocation can be achieved through improved allocation policies and new technology.