The role of azathioprine reduction in late renal allograft failure.

A group of 123 patients who had functioning renal transplants for more than 5 years were studied to discover whether prolonged reduction of azathioprine could predispose to late allograft failure. From the point of entry into the study (5 years after transplantation), the 5-year cumulative graft survival among living-related-donor recipients was 91.7%, and among non-living-related-donor recipients it was 84.8%. The azathioprine dose was reduced in 21 patients, for medical reasons, below 100 mg/day for more than one year when serum creatinine was stable and less than 2 mg/dl. Eight patients subsequently required dialysis. In the control group of 35 patients (transplanted in the same years, with serum creatinine that was similar at the same time posttransplantation to that of those who had azathioprine reduced) only 1 patient required dialysis. The likelihood of dialysis was significantly greater in those who had azathioprine reduced compared with those who did not (chi 2 = 12.0, P less than 0.001). No patient who had azathioprine reduced because of low white cell counts or chronic hepatitis subsequently required dialysis. It was concluded that a prolonged reduction of the azathioprine dose may predispose to late allograft failure.