Assessing the predictive ability of the living kidney donor profile index for graft survival: a single-center study of over 1200 living donor kidney transplants

BACKGROUND: The living kidney donor profile index quantifies living donor kidney quality. Multiple studies, however, have found that the living kidney donor profile index has limited predictive performance for allograft outcomes. METHODS: We applied the living kidney donor profile index to 1232 living donor kidney transplant recipients from our center. In order to test whether the predictive ability could be improved, we evaluated the impact of adding absolute kidney function measures, urine albumin-to-creatinine ratio, and HLA-DQ matching. RESULTS: The living kidney donor profile index was normally distributed with a mean of 20.4 ± 21.8. Each 10-point higher living kidney donor profile index was associated with a 14% higher risk of all-cause graft loss (P < .001; c-statistic = 0.5578). After adjustment for living kidney donor profile index, each 10 mL/min higher creatinine clearance (CrCl) was associated with a 4% lower risk of graft loss (hazard ratio [HR] 0.96, P = .02), improving the c-statistic by 0.0128 (P = .05). Including HLA-A mismatches improved the c-statistic by 0.0110 (P = .01), while including urine albumin-to-creatinine ratio ≥10 mg/g vs. < 10 mg/g, DQ mismatches and diastolic blood pressure (BP) did not significantly increase the c-statistic. CONCLUSIONS: The performance of the living kidney donor profile index in predicting graft loss was modest. Adding absolute donor kidney function and HLA-matching led to marginal improvements in the predictive accuracy of the living kidney donor profile index. This may be because recipient characteristics are a major determinant of recipient outcomes, and even a very healthy living donor kidney will have shorter graft life in an older recipient with multiple comorbidities Further research is needed to guide how best to use the living kidney donor profile index in selecting donors, especially when there are multiple options available, as in kidney paired donation programs.