Transplantation of the human kidney is the treatment of choice for advanced chronic renal failure. Worldwide, tens of thousands of these procedures have been performed with >180,000 patients bearing functioning kidney transplants in the United States today. When azathioprine and prednisone initially were used as immunosuppressive drugs in the 1960s, the results with properly matched familial donors were superior to those with organs from deceased donors: 75–90% compared with 50–60% graft survival rates at 1 year. During the 1970s and 1980s, the success rate at the 1-year mark for deceased-donor transplants rose progressively. Currently, deceased-donor grafts have a 92% 1-year survival and living-donor grafts have a 97% 1-year survival. Although there has been improvement in long-term survival, it has not been as impressive as the short-term survival, and currently the “average” (t1/2) life expectancy of a living-donor graft is around 14 years and that of a deceased-donor graft is close to 10 years.
Mortality rates after transplantation are highest in the first year and are age-related: 2% for ages 18–34 years, 3% for ages 35–49 years, and 6.8% for ages ≥50–60 years. These rates compare favorably with those in the chronic dialysis population even after risk adjustments for age, diabetes, and cardiovascular status. While the loss of kidney transplant due to acute rejection is currently rare, most allografts succumb at varying rates to a chronic process consisting of interstitial fibrosis, tubular atrophy, vasculopathy, and glomerulopathy, the pathogenesis of which is incompletely understood. Overall, transplantation returns most patients to an improved lifestyle and an improved life expectancy compared with patients on dialysis.
RECENT ACTIVITY AND RESULTS
In 2014 there were more than 12,328 deceased-donor kidney transplants and 5574 living-donor transplants in the United States, with the ratio of deceased to living donors remaining stable over the last few years. The backlog of patients with end-stage renal disease (ESRD) has been increasing every year, and it always lags behind the number of available donors. As the number of patients with end-stage kidney disease increases, the demand for kidney transplants continues to increase. As of 2015, there were 50,692 active adult candidates on the waiting list, and <18,000 patients were transplanted. This imbalance is set to worsen over the coming years with the predicted increased rates of obesity and diabetes worldwide. In an attempt to increase utilization of marginal kidneys while insuring longevity-matching, a new allocation system was developed and recently implemented. The main rule is that patients expected to survive the longest receive the allografts expected to last the longest. For this purpose, the Kidney Donor Profile Index (KDPI) score from 0 to 100% has been introduced to quantify the potential risk of graft failure after kidney transplant based on 10 donor factors. The lower KDPI values are associated with higher expected post-transplant survival. Hence, kidneys with KDPI <20% are allocated to the 20% of the potential recipients with the highest expected ...