We read with great interest the recent manuscript of Bittermann and Goldberg exploring the interaction between donor age and recipient age in liver transplant risk prediction.1 Their finding of a differential impact of older donor age based on recipient age, such that the impact of older donor age was seen in younger recipients but not seen in older recipients, is consistent with our previously published “preferred recipient” phenotype,2,3 but misses important components of a preferred recipient phenotype.
While we similarly described a differential impact of older donor age based on recipient age (Figure 1), we found that other medical factors also influenced the impact of donor age on recipient outcomes, so looking at age alone and advocating for policies based on age alone misses half the story.2 In 2007, we conducted a full, formal donor-recipient interaction analysis and identified a preferred phenotype of recipients who incurred no additional risk of graft loss or mortality through acceptance of an older donor: age>45, BMI<35, indication for transplant other than Hepatitis C, and cold ischemia time <8 hours.2 We recently validated this preferred recipient phenotype, showing that, 13 years later, recipients with this phenotype still have similar outcomes with livers from older versus younger donors.3
Figure 1.
Effect modification by age of recipients of ELD livers (age ≥70) from Segev et al, Minimizing risk associated with elderly liver donors by matching to preferred recipients, Hepatology 2007.
With regards to potential allocation policies, these preferred recipients account for more than 40% of the candidate waitlist and span the full range of MELD scores from 6–40 at the same distribution as the entire waitlist, so preferentially allocating older livers to preferred recipients would not violate the spirit of prioritizing high-MELD patients. And perhaps in the era of highly successful treatment for Hepatitis C,4,5 the preferred phenotype could even be further expanded to include patients with this indication for transplantation.
The transplant community has had evidence that we should match marginal donors to preferred recipients for over a decade, and the recent article by Bittermann and Goldberg yet again reminds us of this fact. It could indeed be time to incorporate some type of donor-recipient matching into liver allocation, but basing this on just chronologic age without regard for other recipient factors would be inadequate.
ACKNOWLEDGMENTS
This work was supported by the National Institute of Diabetes and Digestive and Kidney Disease and the National Institute of Aging: grant numbers F32AG053025 (PI: Christine Haugen) and K24DK101828 (PI: Dorry Segev).
Footnotes
Conflict of Interest: Authors have no conflict of interest to report as described by Transplantation.
REFERENCES
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