A kidney transplant replaces a person’s damaged or failing kidney with a healthy one from a donor. The transplanted organ, often called the graft, takes over the functions of the native kidneys. The central question for anyone undergoing this procedure is how long the new organ can function. The lifespan of a transplanted kidney is not indefinite and varies significantly, depending on factors relating to the donor, the recipient, and immune system management.
Average Graft Survival Rates
The source of the transplanted kidney is the greatest predictor of its long-term function. Kidneys from living donors consistently show a better average lifespan than those from deceased donors. In the United States, five-year survival rates for living donor grafts are typically around 85%, sometimes reaching 90%. This superior performance is partly due to the donor’s optimal health and the ability to schedule the surgery.
Transplants from deceased donors generally have five-year survival rates ranging from 70% to 81%. The difference in success rates widens over time. Ten-year survival for living donor grafts often approaches 90% in successful groups. In contrast, the ten-year survival rate for deceased donor grafts is significantly lower, historically falling between 46% and 56% in US data sets.
Key Factors Influencing Longevity
The most influential factor under the recipient’s control is strict adherence to the prescribed regimen of immunosuppressive medications. These drugs prevent the immune system from recognizing the transplanted kidney as foreign and launching a rejection attack. Skipping doses or taking them inconsistently destabilizes the graft, leading to acute or chronic rejection and eventual failure.
The quality of the donor kidney plays a large role. A primary metric is the cold ischemia time (CIT), which is the period the organ spends chilled outside the body until it is surgically reconnected in the recipient. Prolonged CIT, particularly exceeding 18 to 24 hours, causes cellular damage, leading to delayed graft function (DGF) and a higher risk of long-term failure. Kidneys from older donors or expanded criteria donors are more susceptible to this damage.
Immunological compatibility is measured by the tissue match, specifically the Human Leukocyte Antigens (HLA). A better match reduces the likelihood of immune system recognition and subsequent rejection, which drives chronic deterioration. Recipient factors, such as managing pre-existing conditions like diabetes and high blood pressure, are also important. These conditions can damage the small blood vessels within the transplanted kidney, so controlling these comorbidities helps protect the graft and extends its functional life.
Understanding Graft Failure and Next Steps
Graft failure occurs when the transplanted kidney can no longer adequately perform its filtering function. The two main causes of graft loss after the first year are chronic allograft nephropathy (scarring and inflammation of the kidney tissue) and the death of the patient with a still-functioning graft, often due to cardiovascular disease or malignancy. This eventual failure is an expected biological reality.
When graft function declines below a sustainable level, the patient faces two primary courses of action. The first option is to return to dialysis, which involves using a machine or peritoneal method to filter the blood. The second and preferred option is to pursue a second transplantation.
Re-transplantation offers superior quality of life and better long-term patient outcomes compared to remaining on dialysis. For patients who are candidates for a second transplant, a pre-emptive approach provides the best prognosis. This involves placing the new kidney before the failed graft necessitates a return to dialysis. Patients who experience graft failure and return to dialysis face a higher risk of morbidity and mortality compared to those initiating dialysis for the first time.