Lack of improvement in renal allograft survival despite a marked decrease in acute rejection rates over the most recent era.

Acute rejection is known to have a strong impact on graft survival. Many studies suggest that very low acute rejection rates can be achieved with current immunosuppressive protocols. We wanted to investigate how acute rejection rates have evolved on a national level in the U.S. and how this has impacted graft survival in the most recent era of kidney transplantation. For this purpose, we analyzed data provided by the Scientific Registry of Transplant Recipients regarding all adult first renal transplants between 1995 and 2000. We noted a significant decrease in overall acute rejection rates during the first 6 months, during the first year, and also in late rejections during the second year after transplantation. Despite this decrease in the rate of acute rejection, there was no significant improvement in overall graft survival; furthermore, we noted a statistically significant trend towards worse death-censored graft survival. There was also a trend for a greater proportion of rejection episodes to fail to recover to previous baseline function after treatment. Our data suggest that decreasing acute rejection rates between 1995 and 2000 have not led to an increase in long-term graft survival. Part of this discordance might be related to a higher proportion of acute rejections which have not resolved with full functional recovery in more recent years. However, the etiology of this concerning trend for worse death censored graft survival in recent years will warrant further investigation.