Performance of the Integrative Box (iBox) Prognostication System in African American Kidney Transplant Recipients

The integrative box showed accurate discrimination, overall fit, and clinical utility in 3866 kidney transplant recipients from North America. Predictive performance was maintained in African American and non-African American kidney transplant recipients. These results support the robustness of the integrative box as a risk prediction tool.

The integrative box (iBox) is a validated prognostication system that predicts long-term death-censored graft loss in kidney transplant recipients, but its performance in the specific population of African American recipients has not been fully studied.

We conducted a multicenter study including 3866 kidney transplant recipients from North America, of whom 1040 (27%) were African American, to assess the impact of race on the iBox's performance in predicting graft loss. Discrimination, calibration, overall fit, and clinical utility were evaluated in the whole cohort and in African American and non-African American recipients.

Performance metrics for the prediction of graft loss were similar in both subgroups in discrimination (C-index 0.80 [95% confidence interval (CI), 0.77 to 0.83] in African American recipients and 0.83 [95% CI, 0.81 to 0.85] in non-African American recipients, P = 0.07) and observed/expected ratios (1.08 [95% CI, 0.95 to 1.23] and 0.99 [95% CI, 0.88 to 1.10], respectively, P = 0.28). No significant interaction between iBox score values and race was found in multivariable analysis stratified by transplant center ( P = 0.24 for the interaction term). The results were consistent between the subgroups regardless of the equation used to estimate eGFR (Kidney Recipient Specific, CKD-Epidemiology Collaboration, or Modification of Diet in Renal Disease), but with variations in calibration across equations.

The iBox prognostication system showed accurate discrimination, overall fit, and clinical utility up to 7 years after risk evaluation in African American and non-African American kidney transplant recipients, supporting its robustness in this population.

ClinicalTrials.gov, NCT03474003 .