Validation of KDRI/KDPI for the selection of expanded criteria kidney donors.

INTRODUCTION: KDRI / KDPI are tools use in kidney donor evaluation. It has been proposed as a substitute of, or complementary to preimplantation renal biopsy. These scores has not been validated in Spain.

OBJECTIVE: 1) To investigate the concordance between KDPI and histological scores (preimplantation renal biopsy) and 2) To assess the relationship between KDRI, KDPI and histological score on graft survival in the expanded criteria donors group.

METHODOLOGY: Retrospective cohort study from 1 January 1998 until 31 December 2010.

RESULTS: During the study 120 donors were recruited, that resulted in 220 preimplantation renal biopsies. 144 (65%) grafts were considered suitable for kidney transplantation. 76 (34.5%) were discarded. Median follow up has been 6.4 years (sd 3.9). Median age 63.1 years (sd 8.2), males (145; 65.9%), non-diabetic (191; 86.8%) and without another cardiovascular risk factors (173; 78.6%). 153 (69.5%) donors died of cerebrovascular disease. There were significant differences in KDRI/KDPI score in both groups 1.56/89 (sd 0.22) vs 1.66/93 (sd 0.15), p<0.01). The KDPI showed moderate concordance and correlation with the histological score (AUC 0.64 / correlation coefficient 0.24, p <0.01). KDPI (HR 24.3, p<0.01) and KDRI (HR 23.3, p<0.01) scores were associated with graft survival in multivariate analysis.

CONCLUSION: 1) KPDI and histological scores show moderate concordance. The utility of both scores as combined tools it has to be determined. 2) KDPI score, and especially KDRI score, are valid for estimating graft survival and combined with the biopsy can help to individualized decision making in the expanded criteria donors pool.