A thirty percent chronic decline in inverse serum creatinine is an excellent predictor of late renal allograft failure

Abstract

We previously reported that the percentage of change in inverse serum creatinine (Delta1/Cr) was the best of several time-dependent serum creatinine-derived predictors of renal allograft failure in patients not administered cyclosporine (CsA). To further validate the utility of Delta1/Cr, we collected creatinine levels (mean, 90.7 +/- 45.2 creatinine measurements) in 100 patients treated for 6.7 +/- 5.9 years with CsA. We also validated Delta1/Cr using a limited creatinine-sampling strategy, then performed multivariate Cox proportional hazards analysis of 1,663 transplantations. A time-dependent covariate determined by the date of first chronic decline (excluding creatinine levels from periods of acute rejection) in Delta1/Cr to less than -30% of baseline similarly was predictive of graft failure in 101 patients treated without CsA (relative risk, 5.04; 95% confidence interval, 2.18 to 11.6; P = 0.0002) and 100 patients treated with CsA (relative risk, 5.02; 95% confidence interval, 2.50 to 10.1; P < 0.0001). A limited creatinine-sampling strategy (measured at 1 week, 1, 3, 6, 12, 18, 24, and 36 months, and each year thereafter) reduced the ability of Delta1/Cr less than -30% to predict graft failure. In 1,663 patients, Delta1/Cr less than -30% first occurred a median of 1.0 years posttransplantation (n = 792 of 1,663 patients) and 3.0 years before graft failure (n = 478 of 897 patients with graft failure). In a multivariate model (n = 1,663) that included baseline function, acute rejection, and other covariates, Delta1/Cr less than -30% was a strong independent predictor of graft failure (relative risk, 2.56; 95% confidence interval, 2.12 to 3.09; P < 0.0001). Thus, Delta1/Cr less than -30% is an excellent predictor of graft failure that is similarly predictive in patients treated with and without CsA. A limited sampling strategy for creatinine diminishes, but does not negate, the usefulness of Delta1/Cr less than -30%.