Disparities in donor heart acceptance between the USA and Europe: clinical implications

Abstract

Background and aims: Given limited evidence and lack of consensus on donor acceptance for heart transplant (HT), selection practices vary widely across HT centres in the USA. Similar variation likely exists on a broader scale-across countries and HT systems-but remains largely unexplored. This study characterized differences in heart donor populations and selection practices between the USA and Eurotransplant-a consortium of eight European countries-and their implications for system-wide outcomes.

Methods: Characteristics of adult reported heart donors and their utilization (the percentage of reported donors accepted for HT) were compared between Eurotransplant (n = 8714) and the USA (n = 60 882) from 2010 to 2020. Predictors of donor acceptance were identified using multivariable logistic regression. Additional analyses estimated the impact of achieving Eurotransplant-level utilization in the USA amongst donors of matched quality, using probability of acceptance as a marker of quality.

Results: Eurotransplant reported donors were older with more cardiovascular risk factors but with higher utilization than in the USA (70% vs. 44%). Donor age, smoking history, and diabetes mellitus predicted non-acceptance in the USA and, by a lesser magnitude, in Eurotransplant; donor obesity and hypertension predicted non-acceptance in the USA only. Achieving Eurotransplant-level utilization amongst the top 30%-50% of donors (by quality) would produce an additional 506-930 US HTs annually.

Conclusions: Eurotransplant countries exhibit more liberal donor heart acceptance practices than the USA. Adopting similar acceptance practices could help alleviate the scarcity of donor hearts and reduce waitlist morbidity in the USA.

Keywords: Comparative study; Donor selection; Health policy; Heart failure; Heart transplant; Risk factors.

Structured Graphical Abstract

Eurotransplant countries exhibit more liberal donor heart acceptance practices than the USA. Adopting similar acceptance practices could help alleviate the scarcity of donor hearts in the USA. ET, Eurotransplant; HT, heart transplant.

Figure 1

Time trends in donor volume and utilization (2010–20) in Eurotransplant and the USA. Shown are a number of potential donors used for heart transplant (solid bars) and not used for heart transplant (dashed bars), by cohort and year. A different scale (see y-axis labels at left) is used for Eurotransplant and USA donor volume to facilitate comparison. Utilization rate by cohort and year (lines) is calculated as (number of donors used for heart transplant/total number of potential donors).

Figure 2

Comparison of (A) donor age distribution and (B) risk factors amongst potential heart donors in Eurotransplant vs. USA. Shown are number of potential donors used for heart transplant (solid bars) and not used for heart transplant (dashed bars) amongst donors with each listed characteristic. ‘High cardiovascular disease risk’ refers to the presence of age ≥ 50 years, diabetes mellitus, and/or two or more of the following: (i) age 40–49 years, (ii) hypertension, and (ii) smoking history. ‘No cardiovascular disease risk’ refers to the absence of any of these characteristics. ET, Eurotransplant.

Figure 3

Profile of potential donors, by cohort and use for heart transplant (vs. discard). Potential donor subsets include (A) donors used for heart transplant in the USA, (B) donors used for heart transplant in Eurotransplant, (C) donors not used for heart transplant in the USA, and (D) donors not used for heart transplant in Eurotransplant. Numeric labels and the size of each region represent the proportion of donors with a given characteristic (or combination of characteristics). These labels are omitted for regions representing ≤ 1% of donors. ‘Other cardiovascular disease risk factors’ refer to include hypertension, smoking, and diabetes mellitus. CVD, cardiovascular disease; EF, ejection fraction.

Figure 4

Multivariable associations of donor characteristics with utilization for transplant, in Eurotransplant and the USA. Results are obtained from separate logistic models performed for the Eurotransplant and US cohorts, with use for heart transplant (vs. discard) as the dependent variable.

Figure 5

Estimated impact of adopting Eurotransplant-level utilization behaviour on annual heart transplant volume in the USA, by level of donor risk. Shown are a number of potential donors used for heart transplant (solid bars) and not used for heart transplant (dashed bars), by cohort, amongst donors in a given quality decile (as defined in Methods). Adjacent numeric labels (in brackets) denote the estimated number of additional transplants per year in the USA, in the hypothetical scenario where USA adopts ET-level utilization amongst donors in a given quality decile. ‘Median donor’ refers to the specific donor with the median value of quality amongst US donors in each decile. EF, ejection fraction; ET, Eurotransplant; HT, heart transplant; HTN, hypertension.

Figure 6

Transplant volume by year, in hypothetical scenarios where the USA matched ET-level utilization for varying subsets of potential donors (2010–2020). Shown is the progressive increase in transplant volume that would have resulted if the USA had achieved ET-levels of utilization among the top 10%, 30%, and 50% (in terms of donor quality) of potential donors.