Clinicopathological characteristics and effect of late acute rejection on renal transplant outcomes.

Background: Late acute rejection (LAR) has been associated with inferior kidney allograft outcomes.

Methods: We retrospectively evaluated 355 episodes of biopsy-confirmed LAR in a cohort of 5758 kidney transplants performed between 1998 and 2008. Estimated glomerular filtration rate was obtained before, at, and after each LAR episode as well as histology and treatment. Associations of LAR with subsequent death or graft loss were estimated with Cox proportional regression analysis.

Results: A total of 215 patients had 1 episode, 57 had 2 episodes, and 13 had 3 episodes of LAR. Rates of LAR-free survival were 97.4% at 1 year and 93.7% at 5 years. Estimated glomerular filtration rate decreased after each episode of LAR (56±21 vs. 44±18 vs. 36±11 mL/min/1.73 m, P<0.01). The majority of rejections were Banff IA or less, but the chronicity scores as well as plasma cell infiltrates increased after each LAR. All patients requiring dialysis lost their grafts. In a multivariable analysis, the severity of histological score (risk ratio [RR], 3.5; 95% confidence interval [CI], 1.58-7.87; P<0.001), the need for dialysis at LAR (RR, 3.31; 95% CI, 1.44-7.59; P<0.001), and treatment with methylprednisolone (RR, 2.31; 95% CI, 1.07-4.94; P=0.03) were independently associated with graft loss at 5 years, whereas tacrolimus and mycophenolate use was associated with reduced risk (RR, 0.46; 95% CI, 0.25-0.87; P<0.001).

Conclusions: The prevalence and recurrence of LAR are considerable and associated with increased incidence of graft loss. Patients who need dialysis during LAR should be carefully evaluated owing to the high prevalence of graft failure.