EFFECTS OF AZATHIOPRINE WITHDRAWAL IN KIDNEY RECIPIENTS WITH STABLE FUNCTION 2 YEARS AFTER TRANSPLANT

To assess the effects of azathioprine withdrawal, renal recipients wit h grafts >2 yr function (103 study patients) were tapered off azathiop rine over a l-yr period and compared to 69 patients-2 yr after transpl ant who were not tapered (controls). Of the 103 study patients, 16 (15 %) were living-donor transplants and 87 were cadaveric. Of the 69 cont rol patients, 9 (13%) were living related transplants and 60 were cada veric. The mean HLA match for those tapered was 3.3 Ag and 3.1 Ag for those remaining. on azathioprine. Two study patients restarted azathio prine on their own. Age, sex, and cause of renal failure in both group s was similar. Of the 101 study patients remaining, 9 (8.8%) returned to dialysis due to biopsy proven chronic rejection. There were no acut e rejection episodes. Six of the 69 control patients (8.7%) also retur ned to dialysis for the same reason. Of the 92 patients who have compl eted the taper, 85 have been off azathioprine for six or more months. There was not a significant difference between the mean 12- and 24-mon th creatinine levels of the study patients (1.6 mg%, 1.7 mg%) and thos e of the controls (1.5 mg%, 1.8 mg%). The mean 12- and 24-month hemato crits of patients tapered (41.3%, 40.8%) were comparable with patients not tapered (42.3%, 42.8%). Of interest, the mean hematocrits of both study and control patients rose from 28.9% and 33.5%, respectively, t o 41.3% and 42.3% 1 yr following entry into the study. The mean 12- an d 24-month white blood counts of those tapered (8.9, 8.7) did not diff er significantly from those continued on azathioprine (8.8, 8.8). In s table renal transplant patients on triple drug immunosuppression for a t least 2 yr, azathioprine can be discontinued, in a tapered protocol, without an increased risk of graft loss or compromise of renal functi on.