Low absolute glomerular filtration rate in the living kidney donor: a risk factor for graft loss

There is no defined lower acceptable level of glomerular filtration rate (GFR) in potential living kidney donors. Considerations focus on the risk for the donor. We wanted to evaluate the outcome in the recipient in relation to the GFR of the living donor.

There were 344 living donated kidney transplantations performed January 1985 through February 1997 which were evaluated. Two thirds of the donors shared one haplotype with the recipient and 15% shared both. Of the donors 18% were above age 60. The median follow-up time (until graft loss) was 63 months. Before nephrectomy, the donors' GFR had been measured by isotope clearance.

Twenty-six donors (7.6%) had an absolute GFR below 80 ml/min, i.e. not adjusted to 1.73 m2 body surface area (BSA). Cumulative graft survival, censored for graft loss because of death of the patient, was significantly reduced in recipients of grafts from donors with GFR <80 ml/min. A significant correlation between GFR and donor age was observed, but donor age per se was not identified as a risk factor for graft loss. In a Cox stepwise proportional hazards analysis, the relative risk for graft loss was 2.28 with a GFR below 80 ml/min (confidence interval 1.183-4.383, P=0.014) and with sharing one or both haplotypes 0.56 (0.313-0.988, P=0.046) and 0.36 (0.139-0.912, P=0.03), respectively.

An absolute GFR below 80 ml/min in the living donor more than doubles the risk of graft loss. This fact should be considered when definitions of acceptable limits for donor GFR are discussed.