We studied the effect of acute renal allograft rejection and its timing on the development of chronic rejection and subsequent graft loss. Between January 1, 1987 and April 30, 1991, 424 patients at the University of Minnesota received a primary kidney transplant (minimum follow-up, 1 year). Patients were subdivided by donor source, presence or absence of acute rejection, and the timing of acute rejection onset (early, ≤ 60 days vs. late, > 60 days post-transplant). For living donor (LD) transplant recipients (n=219), the incidence of chronic rejection is 0.8% in those who had no acute rejection (n=130), 20% in those with acute rejection ≤60 days (n=59) (P<0.001 vs. no acute rejection), and 43% in those with acute rejection > 60 days (n=30) (P<0.001 vs. no acute rejection, P=0.04 vs. early acute rejection). For cadaver (CAD) transplant recipients (n=205), the incidence of chronic rejection is 0% in those who had no acute rejection (n=109), 36% in those with acute rejection ≤ 60 days (n=69) (P<0.001 vs. no acute rejection), and 63% in those with acute rejection > 60 days (n=27) (P<0.001 vs. no acute rejection, P=0.03 vs. early acute rejection). For both LD and CAD recipients, no grafts have been lost to chronic rejection among those who did not first have at least 1 acute rejection episode. In contrast, 23 patients with acute rejection have had graft loss to chronic rejection. For both LD and CAD recipients, those with > 1 acute rejection episode had significantly more chronic rejection than those with only 1 rejection (P<0.05). There was no significant difference in the incidence of chronic rejection based on whether the first acute rejection episode was steroid resistant or steroid responsive. We conclude that acute rejection is strongly related to the development of biopsy-proven chronic rejection and subsequent graft loss. Patients undergoing their first acute rejection episode > 60 days (vs. ≤ 60 days) have an increased incidence of chronic rejection.
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