Performance of the iBox Prognostication System in African American Kidney Transplant Recipients

Background: The 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. Methods: We conducted a multicenter study including 3,866 kidney transplant recipients from North America, of whom 1,040 (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. Results: Performance metrics for the prediction of graft loss were similar in both subgroups in terms of discrimination (c-index 0.80 [95% CI: 0.77-0.83] in African American recipients and 0.83 [95% CI: 0.81-0.85] in non-African American recipients, p=0.07), and observed/expected ratios (1.08 [95% CI: 0.95-1.23] and 0.99 [95% CI: 0.88-1.10], respectively, p=0.28). No significant interaction between iBox score values and race was found in multivariable analysis stratified by transplant center (p=0.29 for the interaction term). Results were consistent between subgroups regardless of the equation used to estimate glomerular filtration rate (Kidney Recipient Specific [KRS], CKD-EPI, or MDRD), with small variations in calibration across equations. Conclusions: The iBox prognostication system showed accurate discrimination, overall fit, and clinical utility up to 7 years post-risk evaluation in African American and non-African American kidney transplant recipients, supporting its robustness in this population.

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Journal
Journal of the American Society of Nephrology
Published
2026-09-10
DOI
https://doi.org/10.1681/asn.0000001247
Primary Topic
Renal Transplantation Outcomes and Treatments
Type
article
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article

Performance of the iBox Prognostication System in African American Kidney Transplant Recipients

Brad C. Astor, Olivier Aubert, Arthur J. Matas, Didier A. Mandelbrot et al.
Journal of the American Society of Nephrology
Renal Transplantation Outcomes and Treatments
article

Performance of the iBox Prognostication System in African American Kidney Transplant Recipients

Brad C. Astor, Olivier Aubert, Arthur J. Matas, Didier A. Mandelbrot, Agathe Truchot, John J. Friedewald, Dorry Lidor Segev, Edmund Huang, Kenneth A. Newell, Miklos Zsolt Molnar, Gillian Divard, Geeta M. Karadkhele, Marc Raynaud, Andrew Bentall, William E. Fitzsimmons, Roslyn B. Mannon, Alexandre Loupy, Christian P. Larsen, Mark D. Stegall, Gaurav Gupta, Sandesh Parajuli, Enver Akalin, Babak John Orandi, Junji Yamauchi, Yannis Lombardi, Stanley C. Jordan, Katalin Fornadi, Thibaut Thalamas
article en

Abstract

Background: The 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. Methods: We conducted a multicenter study including 3,866 kidney transplant recipients from North America, of whom 1,040 (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. Results: Performance metrics for the prediction of graft loss were similar in both subgroups in terms of discrimination (c-index 0.80 [95% CI: 0.77-0.83] in African American recipients and 0.83 [95% CI: 0.81-0.85] in non-African American recipients, p=0.07), and observed/expected ratios (1.08 [95% CI: 0.95-1.23] and 0.99 [95% CI: 0.88-1.10], respectively, p=0.28). No significant interaction between iBox score values and race was found in multivariable analysis stratified by transplant center (p=0.29 for the interaction term). Results were consistent between subgroups regardless of the equation used to estimate glomerular filtration rate (Kidney Recipient Specific [KRS], CKD-EPI, or MDRD), with small variations in calibration across equations. Conclusions: The iBox prognostication system showed accurate discrimination, overall fit, and clinical utility up to 7 years post-risk evaluation in African American and non-African American kidney transplant recipients, supporting its robustness in this population.

Journal of the American Society of Nephrology
Northwestern University (US), Cedars-Sinai Medical Center (US), Albert Einstein College of Medicine (US), University of Minnesota (US), Montefiore Medical Center (US), University of Wisconsin–Madison (US), Emory University (US), Inserm (FR), Virginia Commonwealth University (US), Université Paris Cité (FR), University of Utah (US), Saint Louis University Hospital (US), University of Rochester Medical Center (US), University of Illinois Chicago (US), Sorbonne Université (FR), NYU Langone Health (US), Assistance Publique – Hôpitaux de Paris (FR), Paris Cardiovascular Research Center (FR), Hôpital Saint-Louis (FR), Mayo Clinic in Florida (US), Hôpital Tenon (FR), New York University (US), University of Nebraska Medical Center (US)
Reduced inequalities, Peace, Justice and strong institutions
Openalex Percentile: Top 8%
Renal Transplantation Outcomes and Treatments
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