Table 5.

Parameters of Model Fit and Complexity in Cox Proportional Hazards Models as a Marker of the Predictive Performance of KDRI and Donor Age for the Outcome of Allograft Survival After Adjustment for Recipient Factors Only (Model 1), Model 1 and US KDRI (Model 2), Model 1 and Donor Age (Model 3), and Model 1 Plus Both US KDRI and Donor Age (Model 4).

Model	Degrees of freedom (complexity)	AIC	-2 Log L (Generalized R2)
Recipient factors only	17	1404.667	1370.667
Recipient + KDRI quintiles	21	1394.423	1352.423 (0.127)
Recipient + Donor age quintiles	21	1395.512	1353.512 (0.126)
Recipient + KDRI + Donor age quintiles	25	1399.773	1349.773

Note. The table displays a summary of model goodness of fit and complexity from 4 Cox proportional hazards models examining the predictive ability of KDRI and donor age. In models 2 and 3, which included recipient factors plus KDRI alone or donor age alone, Nagelkerke’s R² and the AIC were similar, suggesting that the additional predictive value of KDRI over donor age is limited. Model 4, incorporating both donor age and KDRI, was marginally inferior to the model with donor age alone due to an increase in model complexity with limited improvement in model fit. Recipient factors: Age, sex, race, cause of ESRD diabetes, BMI, peak PRA %, duration of pretransplant dialysis, HLA mismatch, and cold ischemia time. KDRI = Kidney Donor Risk Index; HLA = human leukocyte antigen; PRA = panel reactive antibody; AIC = Akaike information criterion.