Helgeson, Erika S.

Background. Delayed graft function (DGF) of a kidney transplant results in increased cost and complexity of management. For clinical care or a DGF trial, it would be ideal to accurately predict individual DGF risk and provide preemptive treatment. A calculator developed by Irish et al has been useful for predicting population but not individual risk. Methods. We analyzed the Irish calculator (IC) in the DeKAF prospective cohort (incidence of DGF = 20.4%) and investigated potential improvements. Results. We found that the predictive performance of the calculator in those meeting Irish inclusion criteria was comparable with that reported by Irish et al. For cohorts excluded by Irish: (a) in pump-perfused kidneys, the IC overestimated DGF risk; (b) in simultaneous pancreas kidney transplants, the DGF risk was exceptionally low. For all 3 cohorts, there was considerable overlap in IC scores between those with and those without DGF. Using a modified definition of DGF—excluding those with single dialysis in the first 24 h posttransplant—we found that the calculator had similar performance as with the traditional DGF definition. Studying whether DGF prediction could be improved, we found that recipient cardiovascular disease was strongly associated with DGF even after accounting for IC-predicted risk. Conclusions. The IC can be a useful population guide for predicting DGF in the population for which it was intended but has limited scope in expanded populations (SPK, pump) and for individual risk prediction. DGF risk prediction can be improved by inclusion of recipient cardiovascular disease.

Background. Glomerular size in renal allografts is impacted by donor–recipient factors and response to injury. In serial biopsies of patients with well-functioning grafts, increased glomerular size correlates with better survival. However, no previous study has addressed the association of glomerular size at the time of a for-cause biopsy and clinical/histopathologic markers of injury, or effect on long-term graft outcome. Methods. Two cohorts of kidney transplant recipients enrolled in the Deterioration of Kidney Allograft Function study were evaluated. The prospective cohort (PC, n = 581): patients undergoing first for-cause kidney biopsy 1.7 ± 1.4 (mean ± SD) y posttransplant; and the cross-sectional cohort (CSC, n = 446): patients developing new-onset renal function deterioration 7.7 ± 5.6 y posttransplant. Glomerular planar surface area and diameter were measured on all glomeruli containing a vascular pole. Kidney biopsy was read centrally in a blinded fashion according to the Banff criteria. Results. Glomerular area was significantly higher in the CSC than the PC; time from transplant to indication biopsy was associated with glomerular area in both cohorts (P values ≤ 0.001). Glomerular area was associated with indices of microvascular inflammation (glomerulitis, peritubular capillary infiltrates; P values ≤ 0.001) and segmental glomerulosclerosis (P value < 0.0001). In the CSC, higher glomerular area was associated with higher estimated glomerular filtration rate (P value ≤ 0.001) and increased graft survival after accounting for microvascular inflammation (adjusted hazard ratio = 0.967; 95% confidence interval: 0.948-0.986; hazard ratio in biopsies without evidence of diabetes or antibody mediated rejection = 0.919, 95% confidence interval: 0.856-0.987). Conclusions. Glomerular size is associated with histopathologic features present at the time of indication biopsy and with increased graft survival in the CSC.