Grant: Project Grant

In many areas of medicine, identification of sex differences in the outcome of a condition has sparked innovative research to understand why these differences exist, leading to new insights into the biology of the condition and how to treat it. Surprisingly, little is known about sex differences in the outcome of organ transplants. Sex differences are of particular interest in organ transplant since the sex of the donor, the sex of the recipient, and the interaction between donor and recipient sex may each play a role. Successful transplantation requires medication to suppress the immune system. There is evidence that females have a stronger immune system than males. Sex differences in the immune system are likely largest among adolescents and young adults, whose immune systems are fully developed but have not started to weaken due to age. Despite this evidence, sex is usually ignored in transplant care and research. This may put females at higher risk of graft loss due to rejection and males at higher risk of infections and cancers. Ignoring the role of sex may also limit our ability to design studies to improve transplant outcomes. We will use large, international transplant databases to compare survival of the graft between male and female kidney, heart, and liver transplant recipients of different ages. We will also compare the survival of grafts based on the sex of the donor. In addition, we will compare the overall excess risk of death and the excess risk of death with a functioning graft in male transplant recipients with those in female transplant recipients. Excess risk is how much more likely transplant recipients are to die than people of the same age and sex in the general population. This will help determine if males are over-immunosuppressed and females under-immunosuppressed. These studies will be the first to determine the roles of recipient and donor sex in graft outcomes, and will lead to fundamental work to figure out why differences exist.