Racial disparities in long-term survival after heart transplantation: What should we be telling patients?

Black heart transplant (HT) recipients continue to have inferior outcomes compared to other race-ethnic groups, including a higher risk of rejection and allograft failure contributing to lower rates of long-term survival in this population.^1-4 It is important for clinicians to understand race-ethnic differences in post-HT survival, so that patients can be counseled accurately. The purpose of this study is to estimate long-term survival after HT by race-ethnicity and recipient age among HT candidates in the United States (US).

Using the United Network for Organ Sharing (UNOS) database, we retrospectively reviewed all adult patients who underwent first-time isolated HT between January 2001 and January 2012 with follow-up through June 2020. Recipients were classified based on self-reported race and ethnicity, including non-Hispanic White, non-Hispanic Black, Hispanic, and Asian. Kaplan-Meier analysis was used to examine median post-transplant survival over three eras (2001–2004; 2005–2008; 2009–2012) and age groups (18–40; 41–60; and >60 years). Multivariable Cox proportional hazard regression was used to construct adjusted survival estimates for each race and ethnic group at defined time points adjusted for the recipient (age, sex, race, ABO blood group, body mass index, insurance status, heart failure etiology, mechanical ventilation, mechanical circulatory support, history of dialysis, hypertension, diabetes, tobacco use, cerebrovascular disease, panel reactive antibody levels), donor (age, sex, race, height, ischemic time), and center (HT volume per year) variables. The need for Institutional Review Board approval was waived owing to the use of de-identified data from a publicly available registry.

During the study period, 22 133 patients (mean age 52 ± 12 years, 29% female, 72% White) received a HT, and the median follow-up time post-HT was 8.3 years (interquartile range [.2, 19.3]). The number of HT performed was similar across the 3 eras (2001–2004 n = 7186; 2005–2008 n = 7275; 2009–2012 n = 7672], and 12 325 (56%) HT were performed in candidates aged 41–60 years. Baseline differences in clinical characteristics by the race-ethnic group are provided in Table S1. Overall, Black HT recipients experienced worse survival than Asian, Hispanic, or White recipients (Figure 1A). When examining post-HT survival stratified according to age groups, Black recipients had the worst survival among those aged 18–40 (Figure 1B) and 41–60 (Figure 1C) years. For patients >60 years (Figure 1D), there were no differences in survival between race-ethnic groups. While long-term survival improved across the three eras and for each race-ethnic group, differences in median survival by race-ethnicity persisted (Figure 2). Specifically, Black HT recipients had the lowest median survival, while Hispanic HT recipients had the greatest improvement in survival during the study period.

FIGURE 1.

Trends in median survival following HT by race examined in three time periods between 2001 and 2012

FIGURE 2.

Long term post-transplant survival by race and age categories

Table 1 displays the risk-adjusted survival estimates for all recipients at 1-year, and risk-adjusted conditional survival estimates at 3- and 5-years post-HT stratified by age group and race-ethnicity. Among recipients aged 18–40, risk-adjusted conditional median survival was 11.8 years in Black recipients compared to 14–15 years in other race-ethnic groups. Similarly, in patients aged 41–60 years, Black HT candidates had the lowest long-term survival compared to other race-ethnic groups. There was no difference in long-term survival among recipients aged >60 years. The primary causes of post-HT mortality by race-ethnic group are given in Table S2. Cardiopulmonary causes were the most common mode of death in HT recipients across all race-ethnic groups. This was followed by allograft dysfunction in Black recipients, infection in Hispanic and Asian recipients, and malignancy in White recipients.

TABLE 1.

Risk adjusted post-transplant survival for all HT recipients by categories of race-ethnicity and age

	Post-HT survival
Race	1-yr (%)	3-yra (%)	5-yra (%)	Mediana
All recipients
White	91.8	94.5	89.6	14.2
Black	89.6	91.1	84.5	12.6
Hispanic	90.6	94.0	88.7	14.9
Asian	92.9	93.7	88.8	15.3
All recipients	92.7	94.8	90.3	15.1
Recipient age: 18–40 years
White	93.5	92.4	87.4	15.1
Black	87.3	87.5	79.5	11.8
Hispanic	90.7	93.5	87.2	15.1
Asian	93.1	90.2	81.5	15.2
All recipients	92.2	91.8	86.2	15.1
Recipient age: 41–60 years
White	92.3	95.2	90.8	15.2
Black	92.8	92.8	87.1	14.2
Hispanic	91.8	94.6	89.9	15.4
Asian	94.6	95.1	91.5	14.8
All recipients	94.3	96.0	92.4	15.3
Recipient age: >60 years
White	90.2	94.3	88.5	12.4
Black	85.1	93.4	87.9	11.3
Hispanic	89.1	94.0	89.4	13.2
Asian	89.8	94.3	89.6	12.9
All recipients	90.5	94.8	89.6	13.4

Abbreviation: HT, Heart Transplantation.

^a3-yr, 5-yr, and median survival estimates are conditional based on 1-year survival.

The present analysis highlights the persistent disparity in survival by race-ethnicity and provides survival estimates that should be understood by clinicians so that accurate survival expectations are translated to HT candidates. Although patients are often quoted a median conditional survival of 13 years after HT, this estimate varies significantly by the race-ethnicity and age of the recipient. Our findings demonstrate that the median conditional survival after HT is 15.3 years for Asian, 14.9 years for Hispanic, 14.2 years for White, and 12.6 years for Black recipients. Differences in long-term survival were more pronounced in young adults ages 18–40, among whom Black HT recipients experienced a median survival 3-years less than that of recipients in other race-ethnic groups. Possible mechanisms that may influence lower survival in Black patients include a higher acuity of illness and comorbidities at the time of listing, socioeconomic and other financial constraints that may be more substantial for younger patients, and heightened immune response that mediates a higher risk of subclinical allograft injury in the early post-HT period, acute and chronic cellular and humoral rejection, and graft failure during follow up.⁵ Conversely, Asian and Hispanic HT recipients had similar or longer median post-HT survival than White HT recipients in each age category. Although Black and Hispanic Americans with HF often have a similar burden of socioeconomic and traditional CV risk factors (Table S1), the disparity in survival even among these two groups highlights the need for further research to examine non-traditional risk factors that contribute to disparities in post-HT survival.

This report highlights the persistent disparity in long-term survival after HT by race, particularly among young Black adults who have the greatest risk for mortality after HT. Understanding estimated survival times in discrete groups according to race-ethnicity and age might allow for more accurate patient counseling, to set appropriate expectations for patients who are being considered for HT. We hope that providing race- and age-specific estimates will not only motivate high-risk patients to engage more purposefully and vigilantly in their care, but also serve as a call to action to the HT community to continue research that will help close the gap in long-term outcomes.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.