The impact of residual renal function on graft and patient survival rates in recipients of preemptive renal transplants

Background Transplantation before the initiation of dialysis is associated with prolonged allograft survival. It is unclear if this benefit is attributable to greater residual renal function or to avoidance of dialysis exposure. The authors performed an analysis to determine whether higher renal function at transplant was associated with increased patient and graft survival rates. Methods: The authors identified individuals who between 1994 and June 2000 were at greater than or equal to 18 years and had undergone a living donor renal transplant (Tx) as initial form of renal replacement therapy. Pre-Tx and 6-month estimated glomerular filtration rates (eGFR) were calculated using the 4-variable Modification of Diet in Renal Disease formula. Survival was compared in those with a pre-Tx eGFR greater than or equal to 15 mL/min to those with an eGFR less than 15 mL/min, after adjusting for demographic variables, co-morbidities, and transplant characteristics. Survival rate then was adjusted for calculated propensity scores. Results: A total of 4,046 patients were included. Mean pre-Tx eGFR was 9.9 mL/min (0.9 to 57.1 mL/min). There was no difference in graft survival rates by strata of eGFR in any of the tested models, even after correcting for propensity score (hazard ratio, 0.95; 95% confidence interval, 0.69 to 1.30). There was no correlation between pre-Tx eGFR and 6-month post-Tx eGFR (r(2) = -0.005). Conclusion: Recipients of preemptive transplants fair equally, regardless of the eGFR at which they receive their transplant. There was no relationship between pre-Tx eGFR and 6-month eGFR, suggesting that post-Tx renal function is independent of the level of pre-Tx renal function. These data suggest that preemptive kidney transplantation should be delayed as long as possible, provided the patient does not have uremic symptoms, and dialysis can be safely avoided. (C) 2003 by the National Kidney Foundation, Inc.