Title:
Time-dependent prognostic effects of recipient and donor age in adult heart transplantation.

Abstract:
Recipient age and donor age are well-known prognostic factors in adult heart transplantation. However, the association between donor age and recipient age and their interaction and short- and long-term mortality is unknown.
We studied 64,354 heart transplants to adult recipients between 1988 and 2013 in the ISHLT Registry. Donor age and recipient age were analyzed as continuous and categorical variables and restricted cubic spline functions to assess non-linear associations and interactions. The end-point was all-cause mortality.
In the multivariable analysis, the odds ratio for 30-day mortality per 10-year increase in recipient age was 1.05 (95% confidence interval [CI] 1.01 to 1.08, p = 0.009) compared with 1.19 (95% CI 1.15 to 1.22, p < 0.001) for donor age. In the first year, the hazard ratio for mortality was 1.05 (95% CI 1.02 to 1.07, p < 0.001) for a 10-year increase in recipient age and 1.16 (1.14 to 1.18, p < 0.001) for donor age. In Years 1 to 3, 3 to 5, and 5 to 10 post-transplant, the hazard ratio was 0.89 (95% CI 0.86 to 0.92, p < 0.001), 0.98 (95% CI 0.94 to 1.02, p = 0.266), and 1.14 (95% CI 1.11 to 1.17, p < 0.001) for recipient age, and 1.12 (95% CI 1.08 to 1.14, p < 0.001), 1.07 (95% CI 1.03 to 1.10, p < 0.001), and 1.07 (95% CI 1.05 to 1.10, p < 0.001) for donor age, respectively. There was no interaction of recipient age and donor age with survival at any follow-up time-point.
At 30 days, both higher donor age and recipient age were associated with higher mortality. At 1 to 10 years, older donor age was associated with higher mortality at all follow-up time-points, but the hazard was greater in the short term, and recipient age was associated only with longer term mortality. The risk from donor age appears equal across recipient age groups.