Comparing methods for monitoring serum creatinine to predict late renal allograft failure

Few studies have systematically investigated what changes in chronic renal allograft function best predict subsequent graft failure, when these change s occur, and whether they occur soon enough to allow possible intervention. We collected serum creatinine values (mean, 183 +/- 75 values/patient) mea sured over a maximum follow-up of 22 years in 101 consecutive renal transpl ant recipients (excluding creatinine levels from periods of acute rejection ). We determined the dates of first decline in inverse creatinine (Deltal/C r; < -20%, -30%, -40%, -50%, and -70%), declines in estimated creatinine cl earance (CCr; <55, 45, 35, 25, and 15 mL/min), and declines in measured slo pe of 1/Cr over time. We used time-dependent covariates in Cox proportional hazards analyses to determine the relative effect of each renal function p arameter on outcomes while adjusting for other risk factors. The best predi ctor of subsequent graft failure was Delta1/Cr. Delta1/Cr less than -40% fi rst occurred at a median of 1.28 years after transplantation in 73 patients , and 67 patients went on to have graft failure a median of 3.28 years afte r Delta1/Cr less than -40%. The independent relative risk for graft failure attributable to Delta1/Cr less than -40% was 5.91 (95% confidence interval , 3.25 to 10.8; P < 0.0001). A decline in CCr, eg, less than 45 mL/min, als o was a strong predictor of subsequent graft failure. Conversely, declines in allograft function estimated from slopes of 1/Cr were poor predictors of graft failure. In analysis limited to patients followed up for 2.5 years o r less, <Delta>1/Cr continued to predict graft failure, suggesting that Del ta1/Cr will be a useful predictor in populations with shorter follow-up. If confirmed in other populations, eg, patients treated with calcineurin inhi bitors, this simple marker of chronic allograft dysfunction may prove to be a practical tool for defining patients at high risk for late graft failure . (C) 2001 by the National Kidney Foundation, Inc.