Balancing rejection and infection with respect to age, race, and gender: Clues acquired from 17 years of cardiac transplantation data

BACKGROUND: Donor and recipient risk factors for rejection and infection have been well characterized. The contribution of demographic factors, especially age at the time of transplantation to morbidity and mortality due to rejection and infection, is much less well understood. METHODS: Using parametric hazard analysis and multivariate risk-factor equations for infection and rejection events, we quantitatively determined the relationship of fundamental demographic variables (age, race and gender) to infection and rejection. These analyses were conducted with respect to date of transplant and age at the time of transplantation. The patient group consisted of all primary heart transplants performed at the University of Alabama at Birmingham during the years 1990 to 2007 (n = 526). RESULTS: Risk factors for rejection within 12 months post-transplantation were date of transplant (p < 0.0001) and age at the time of transplantation (young adults 10 to 30 years of age, p < 0.0001). Risk factors for infection were date of transplant (p < 0.0001) and age at the time of transplantation (young children and older adults, p < 0.0001). There were three immunosuppressive eras in 1990 to 2007. Notably, although the proportion of patients experiencing rejection and infection events decreased during each successive immunosuppressive era, the relative relationship of infection to rejection, as well as age at the time of transplantation, remained similar into the most recent era. The maximal frequency of rejection events and rejection death occurred among patients transplanted at ages 10 to 30 years. Conversely, the frequency of infection events was minimal within the same group. In the oldest and youngest patients receiving transplants, infection was the predominant cause of death and rates of rejection events decreased. CONCLUSIONS: These data show that evolving immunosuppressive strategies have successfully reduced rejection and infection frequencies, and those patients transplanted at 30 to 60 years of age have the lowest frequency of rejection/infection events. However, individuals transplanted at younger or older ages, especially non-white recipients in the 10- to 30-year age group, experience significantly more infection or rejection. Therefore, programs should increase the level of surveillance in these patients and consider modification of immunosuppressive regimens in order to lower the frequency of infection and rejection events.