Abstract
Background:
Chronic Kidney Disease (CKD) Epidemiology Collaboration eGFR 2021 formula removed Black race from the 2009 equation. Unintended consequences may lead to reclassifying Black living kidney donors as having more advanced CKD, exacerbating racial disparities in living donation.
Methods:
We used national data to quantify CKD stage reclassification based on eGFR for Black living donors both pre- and post-donation.
Results:
Among 6,365 Black living donors, 17.7% were reclassified as having a higher CKD stage pre-donation with the 2021 formula. Among 4,149 Black living donors with at least 2 creatinine measurements post-donation, 25.5% were reclassified as having a higher CKD stage post-donation with the 2021 formula.
Conclusion:
Eliminating race in the formula may inappropriately label Black potential donors with CKD. These data highlight the need for a validated eGFR formula for donors, use of measured and not eGFR, and education of non-transplant providers regarding interpretation of CKD staging in living donation.
INTRODUCTION
Recent changes to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula for estimated glomerular filtration rate (eGFR) (2021 CKD-EPI) removed Black race from the 2009 equation, with the goal of not disproportionately affecting one racial group.1 The 2021 formula has removed the 1.159 correction factor applied to Black patients that will systematically decrease their eGFR.2 These changes will lead to a greater proportion of Black patients labelled (sometimes mislabeled) as having CKD,1 facilitating access to specialists and earlier transplant referral.3 Unintended consequences of this change will lead to reclassifying potential Black living kidney donors as having more advanced CKD, potentially exacerbating existing disparities in living donation access,4,5 and classifying Black donors into a higher CKD stage post-donation. We sought to quantify the potential reclassification effect on living donors using U.S. national data.
METHODS
Using Scientific Registry of Transplant Recipients data, we identified adult living kidney-only donors from January 01, 2010 through March 03, 2021 with pre-donation eGFR≥60 ml/min—consistent with living donor guidelines6—to quantify the magnitude of CKD stage reclassification for Black and non-Black living kidney donors pre- and post-donation for the main analysis. We calculated pre-donation Kidney Disease: Improving Global Outcomes (KDIGO) CKD G-stage based on eGFR using the 2009 formula and the reclassification of CKD stage using the race-free 2021 formula. Transplant centers are required to obtain 6-, 12-, and 24-month post-donation laboratory testing. Post-donation follow-up CKD stage based on 2009 and 2021 formulas was selected from the higher of the two lowest eGFRs.7,8 Finally, because of controversy surrounding the implication of a lower GFR in people with more advanced ages (e.g., that lower GFR may just be a normal part of the aging process rather than evidence of disease), we estimated the discrepancy in presence versus absence of CKD based on eGFR between the two formulas using age-defined eGFR cutoffs (CKD defined by eGFR <75 ml/min/1.73 m2 for individuals <40 years of age; <60 ml/min/1.73 m2 for individuals 40–65 years of age; and <45 ml/min/1.73 m2 for individuals >65 years of age).9
Multiracial donors (n=554) were excluded because of an inability to determine which race to assign them to for the 2009 race-based formula. Chi-square and t-tests were used to compare between-group characteristics. To assess CKD stage agreement between formulas, we calculated Cohen’s kappa by race (Black/non-Black) and donation status (pre-/post-donation). This study was IRB-approved. Individual consent was not required as the data are de-identified and publicly-available.
RESULTS
Pre-donation
Among 63,246 donors, 11.2% (n=6,365) were Black and had a mean serum creatinine of 0.88 mg/dl (Table 1). Black donors’ eGFR was 109.7 ml/min/1.73m2 using the 2009 formula and 97.7 ml/min/1.73m2 using the 2021 formula. Among Black donors, based on 2009 versus 2021 formulas, CKD stage classification was 82.0% versus 65.2% for CKD stage 1, 18.0% versus 34.0% for CKD stage 2, 0.0% versus 0.9% for CKD stage 3, 0.0% versus 0.0% for CKD stage 4, and 0.0% versus 0.0% for CKD stage 5 (Cohen’s kappa 0.56; 95% CI: 0.54–0.58) (Table 2). Overall, 17.7% of Black donors were classified as having a higher CKD stage pre-donation with the 2021 formula.
Table 1.
Demographics and CKD stage for Black and non-Black kidney donors pre- and post-donation.
| Pre-donation | Post-donation | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Black donors (n=6,365) | Non-Black donors (n=56,881) | P-value | Black donors (n=4,149) | Non-Black donors (n=40,376) | P-value | |||||
| Mean age (SD) | 38.6 (11.3) | 43.3 (12.1) | <0.001 | 40.5 (11.4) | 45.2 (12.1) | <0.001 | ||||
| Female (%) | 3,859 (60.6%) | 36,022 (63.3%) | <0.001 | 2,610 (62.9%) | 26,053 (64.5%) | 0.04 | ||||
| Mean months since donation (SD) | -- | -- | -- | 12.8 (7.1) | 12.7 (7.1) | 0.6 | ||||
| Mean serum creatinine (mg/dl) | 0.88 (0.19) | 0.81 (0.16) | <0.001 | 1.24 (0.27) | 1.15 (0.23) | <0.001 | ||||
| eGFR formula | 2009 | 2021 | 2009 | 2021 | 2009 | 2021 | 2009 | 2021 | ||
| Mean eGFR (ml/min/1.73 m 2 ) (SD) | 109.69 (20.39) | 97.69 (17.12) | 97.90 (16.32) | 101.17 (15.52) | 73.22 (16.78) | 65.64 (14.52) | 66.60 (15.04) | 69.40 (15.02) | ||
| CKD Stage (%) | ||||||||||
| 1 | 5,217 (82.0%) | 4,147 (65.2%) | 38,378 (67.5%) | 42,443 (74.6%) | 590 (14.2%) | 235 (5.7%) | 2,956 (7.3%) | 3,772 (9.3%) | ||
| 2 | 1,148 (18.0%) | 2,161 (34.0%) | 18,503 (32.5%) | 14,438 (25.4%) | 2,663 (64.2%) | 2,313 (55.7%) | 22,609 (56.0%) | 25,078 (62.1%) | ||
| 3 | 0 (0.0%) | 57 (0.9%) | 0 (0.0%) | 0 (0.0%) | 896 (21.3%) | 1,600 (38.6%) | 14,808 (36.7%) | 11,524 (28.5%) | ||
| 4 | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 1 (0.0%) | 3 (0.0%) | 2 (0.0%) | ||
| 5 | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | ||
| Cohen’s kappa coefficient* (95% CI) | 0.56 (0.54 – 0.58) | 0.83 (0.82 – 0.83) | 0.54 (0.51 – 0.56) | 0.82 (0.81 – 0.82) | ||||||
SD – standard deviation, CI – confidence interval
The Cohen’s kappa coefficient is used to assess inter-rater (or in this case, inter-formula) agreement. Generally, coefficient values 0.40–0.59 suggest weak agreement and values 0.80–0.90 suggest strong agreement (McHugh ML. Interrater reliability: the kappa statistic. Biochem Med (Zagreb). 2012;22(3):276–82.).
Table 2.
Cross-tabulation of CKD stage based on eGFR as calculated by the 2009 and 2021 CKD-EPI formulas for Black donors pre- and post-donation.
| CKD Stage Based on 2021 CKD-EPI Formula | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Pre-Donation | Post-Donation | ||||||||||||
| 1 | 2 | 3 | 4 | 5 | 1 | 2 | 3 | 4 | 5 | ||||
| CKD Stage Based on 2009 CKD-EPI Formula | 1 | 4,147 | 1,070 | 0 | 0 | 0 | 5,217 (82.0%) | 235 | 355 | 0 | 0 | 0 | 590 (14.2%) |
| 2 | 0 | 1,091 | 57 | 0 | 0 | 1,148 (18.0%) | 0 | 1,958 | 705 | 0 | 0 | 2,663 (64.2%) | |
| 3 | 0 | 0 | 0 | 0 | 0 | 0 (0.0%) | 0 | 0 | 895 | 1 | 0 | 896 (21.6%) | |
| 4 | 0 | 0 | 0 | 0 | 0 | 0 (0.0%) | 0 | 0 | 0 | 0 | 0 | 0 (0.0%) | |
| 5 | 0 | 0 | 0 | 0 | 0 | 0 (0.0%) | 0 | 0 | 0 | 0 | 0 | 0 (0.0%) | |
| 4,147 (65.1%) | 2,161 (33.9%) | 57 (0.9%) | 0 (0.0%%) | 0 (0.0%) | 6,365 (100%) | 235 (5.7%) | 2,313 (55.7%) | 1,600 (38.6%) | 1 (0.0%) | 0 (0.0%) | 4,149 (100%) | ||
Pre-donation, among non-Black donors, 67.5% (n=38,378) were classified as having CKD stage 1 and 32.5% (n=18,503) as having CKD stage 2 based on the 2009 CKD-EPI formula; after applying the 2021 CKD-EPI formula, 74.6% (n=42,443) were classified as having CKD stage 1 and 25.4% (n=14,438) were classified as having CKD stage 2 (Cohen’s kappa 0.83; 95% CI: 0.82–0.83) (Table 3). Overall, 7.1% (n=4,065) of non-Black donors were reclassified as having a lower CKD stage pre-donation with the application of the 2021 CKD-EPI formula.
Table 3.
Cross-tabulation of CKD stage based on eGFR as calculated by the 2009 and 2021 CKD-EPI formulas for non-Black donors pre- and post-donation.
| CKD Stage Based on 2021 CKD-EPI Formula | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Pre-Donation | Post-Donation | ||||||||||||
| 1 | 2 | 3 | 4 | 5 | 1 | 2 | 3 | 4 | 5 | ||||
| CKD Stage Based on 2009 CKD-EPI Formula | 1 | 38,378 | 0 | 0 | 0 | 0 | 38,378 (67.5%) | 2,956 | 0 | 0 | 0 | 0 | 2,956 (7.3%) |
| 2 | 4065 | 14,438 | 0 | 0 | 0 | 18,503 (32.5%) | 816 | 21,793 | 0 | 0 | 0 | 22,609 (56.0%) | |
| 3 | 0 | 0 | 0 | 0 | 0 | 0 (0.0%%) | 0 | 3,285 | 11,523 | 0 | 0 | 14,808 (36.7%) | |
| 4 | 0 | 0 | 0 | 0 | 0 | 0 (0.0%%) | 0 | 0 | 1 | 2 | 0 | 3 (0.0%) | |
| 5 | 0 | 0 | 0 | 0 | 0 | 0 (0.0%%) | 0 | 0 | 0 | 0 | 0 | 0 (0.0%) | |
| 42,443 (74.6%) | 14,438 (25.4%) | 0 (0.0%%) | 0 (0.0%) | 0 (0.0%%) | 56,881 (100%) | 3,772 (9.3%) | 25,078 (62.1%) | 11,524 (28.5%) | 2 (0.0%) | 0 (0.0%) | 40,376 (100%) | ||
Post-donation
Among 44,525 donors with ≥2 creatinine measurements post-donation, 9.3% (n=4,149) were Black and had a mean serum creatinine of 1.24 mg/dl. Black donors’ mean eGFR was 73.2 ml/min using the 2009 formula and 65.6 ml/min/1.73m2 using the 2021 formula. Among Black donors, based on 2009 versus 2021 formulas, CKD stage classification was 14.2% versus 5.7% for CKD stage 1, 64.2% versus 55.7% for CKD stage 2, 21.6% versus 38.6% for CKD stage 3, 0.0% versus 0.0% for CKD stage 4, and 0.0% versus 0.0% for CKD stage 5 (Cohen’s kappa 0.54; 95% CI: 0.51–0.56). Overall, 25.5% of Black donors were classified as having a higher CKD stage post-donation with the 2021 formula.
Post-donation among non-Black donors, 7.3% (n=2,956) were classified as having CKD stage 1, 56.0% (n=22,609) as having CKD stage 2, 36.7% (n=14,808) as having CKD stage 3, and 0.0% (n=3) as having CKD stage 4 based on the 2009 CKD-EPI formula; after applying the 2021 CKD-EPI formula, 9.3% (n=3,772) of non-Black donors were classified as having CKD stage 1, 62.1% (n=25,078) as having CKD stage 2, 28.5% (n=11,524) as having CKD stage 3, and 0.0% (n=2) as having CKD stage 4 (Cohen’s kappa 0.82; 95% CI: 0.81–0.82). Overall, 10.1% (n=4,101) of non-Black donors were reclassified as having a lower CKD stage post-donation with the application of the 2021 CKD-EPI formula.
Age-defined CKD
Pre-donation, 3.1% (n=110), 1.4% (n=40), and 0.0% (n=0) of Black donors age<40, age 40–65, and age>65 would be classified as having CKD using age-defined thresholds with eGFR based on the 2021 CKD-EPI formula that would not have CKD based on the 2009 CKD-EPI formula (Table 4). Post-donation, 25.3% (n=512), 21.5% (n=446), and 12.8% (n=6) of Black donors age<40, age 40–65, and age>65 would be classified as having CKD using age-defined thresholds with eGFR based on the 2021 CKD-EPI formula that would not have CKD based on the 2009 CKD-EPI formula.
Table 4.
Presence of CKD based on age-specific eGFR cutoffs for Black donors both pre- and post-donation.
| Black Donors | ||||||||
|---|---|---|---|---|---|---|---|---|
| Age Range | CKD Based on 2021 CKD-EPI Formula | |||||||
| Pre-Donation | Post-Donation | |||||||
| No CKD | CKD | Total | No CKD | CKD | Total | |||
| CKD Based on 2009 CKD-EPI Formula | Age<40 | No CKD | 3346 | 110 | 3456 (98.8%) | 702 | 512 | 1214 (59.9%) |
| CKD | 0 | 41 | 41 (1.2%) | 0 | 812 | 812 (40.1%) | ||
| Total | 3346 (95.7%) | 151 (4.3%) | 3497 (100%) | 702 (34.6%) | 1324 (65.3%) | 2026 (100%) | ||
| Age 40–65 | No CKD | 2773 | 40 | 2813 (100%) | 893 | 446 | 1339 (64.5%) | |
| CKD | 0 | 0 | 0 (0%) | 0 | 737 | 737 (35.5%) | ||
| Total | 2773 (98.6%) | 40 (1.4%) | 2813 (100%) | 893 (43.0%) | 1183 (57.0%) | 2076 (100%) | ||
| Age>65 | No CKD | 55 | 0 | 55 (100%) | 34 | 6 | 40 (85.1%) | |
| CKD | 0 | 0 | 0 (0%) | 0 | 7 | 7 (14.9%) | ||
| Total | 55 (100%) | 0 (0%) | 55 (100%) | 34 (72.3%) | 13 (27.7%) | 47 (100%) | ||
CKD defined by eGFR <75 ml/min/1.73 m2 for individuals <40 years of age; <60 ml/min/1.73 m2 for individuals 40–65 years of age; and <45 ml/min/1.73 m2 for individuals >65 years of age.
Pre-donation, 0.7% (n=156), 0.0% (n=0), and 0.0% (n=0) of non-Black donors age<40, age 40–65, and age>65 would be classified as not having CKD using age-defined thresholds with eGFR based on the 2021 CKD-EPI formula that would have CKD based on the 2009 CKD-EPI formula (Table 5). Post-donation, 6.8% (n=942), 10.1% (n=2538), and 8.4% (n=136) of non-Black donors age<40, age 40–65, and age>65 would be classified as not having CKD using age-defined thresholds with eGFR based on the 2021 CKD-EPI formula that would have CKD based on the 2009 CKD-EPI formula.
Table 5.
Presence of CKD based on age-specific eGFR cutoffs for non-Black donors both pre- and post-donation.
| Non-Black Donors | ||||||||
|---|---|---|---|---|---|---|---|---|
| Age Range | CKD Based on 2021 CKD-EPI Formula | |||||||
| Pre-Donation | Post-Donation | |||||||
| No CKD | CKD | Total | No CKD | CKD | Total | |||
| CKD Based on 2009 CKD-EPI Formula | Age<40 | No CKD | 21867 | 0 | 21867 (97.6%) | 6734 | 0 | 6734 (49.0%) |
| CKD | 156 | 369 | 525 (2.3%) | 942 | 6056 | 6998 (51.0%) | ||
| Total | 22023 (98.3%) | 369 (1.6%) | 22392 (100%) | 7676 (55.9%) | 6056 (44.1%) | 13732 (100%) | ||
| Age 40–65 | No CKD | 32902 | 0 | 32902 (100%) | 13025 | 0 | 13025 (52.1%) | |
| CKD | 0 | 0 | 1587 (100%) | 2538 | 9456 | 11994 (47.9%) | ||
| Total | 32902 (100%) | 1587 (100%) | 32902 (100%) | 15563 (62.2%) | 9456 (37.8%) | 25019 (100%) | ||
| Age>65 | No CKD | 1587 | 0 | 1587 (100%) | 1339 | 0 | 1339 (82.4%) | |
| CKD | 0 | 0 | 0 (0.0%) | 136 | 150 | 286 (17.6%) | ||
| Total | 0 (0.0%) | 0 (0.0%) | 1587 (100%) | 1475 (90.8%) | 150 (9.2%) | 1625 (100%) | ||
CKD defined by eGFR <75 ml/min/1.73 m2 for individuals <40 years of age; <60 ml/min/1.73 m2 for individuals 40–65 years of age; and <45 ml/min/1.73 m2 for individuals >65 years of age.
DISCUSSION
In this nationwide study, we demonstrate that the new 2021 refitted, race-free eGFR formula had the effect of reclassifying 17.7% and 25.5% of Black donors pre- and post-donation as having a higher CKD stage. While eGFR formulas were not developed or intended for use in living donors, and some transplant centers do not use eGFR in screening, exclusion of race in the formula may exacerbate existing racial disparities in access to living kidney donation as most living donors and recipients are racially concordant.4 The disparity is further widened because more non-Black donors will be reclassified to a lower CKD stage; the disparity is similar when employing age-specific cutoffs for CKD.
While transplant centers can and should rely on measured GFR to evaluate donors, only 30% of transplant centers actually use iothalamate or iohexol GFR measurements on donor candidates.10 Importantly, potential donors may be less inclined to come forward for evaluation altogether if they are aware of having a label of CKD stage 2 or 3 prior to evaluation, thereby missing the opportunity to undergo actual GFR measrurement. Primary care providers may discourage donation based on that diagnosis as Black donors may have an increased risk of hypertension, diabetes, CKD, and ESKD post-donation.11,12 The actual clinical impact of these changes on potential donors is unknown and requires further study.
Post-donation, being labelled as having more advanced CKD can be problematic as most donors do not follow-up with their transplant center.13 Primary care providers for these donors may use eGFR to disproportionately label Black donors as having CKD, leading to distress for Black donors and guilt for their recipients, unnecessary therapies and dietary restrictions, as well as challenges in acquiring health and life insurance.
Retrospective study design precluded demonstrating causality between 2021 formula adoption and fewer Black kidney donors and/or adverse outcomes post-donation. Lack of data regarding renal parenchymal disease precluded the ability to accurately diagnose CKD stages 1 or 2 for patients with GFR ranges consistent with CKD stages 1 or 2; however, given widespread and potentially indiscriminate eGFR adoption in clinical use, it is worth considering unintended consequences such as mislabeling patients with a disease state, and particularly in populations for which the formulas have not been validated (e.g., living donors). These data highlight the need for: a validated eGFR formula for living donors, GFR measurement rather than estimation, and additional education of potential and actual donors and their care teams regarding CKD staging interpretation in this context.
Acknowledgements:
This study used data from the Scientific Registry of Transplant Recipients (SRTR). The SRTR data system includes data on all donor, wait-listed candidates, and transplant recipients in the US, submitted by the members of the Organ Procurement and Transplantation Network (OPTN). The Health Resources and Services Administration (HRSA), U.S. Department of Health and Human Services provides oversight to the activities of the OPTN and SRTR contractors. The data reported here have been supplied by the Hennepin Healthcare Research Institute (HHRI) as the contractor for the Scientific Registry of Transplant Recipients (SRTR). The interpretation and reporting of these data are the responsibility of the author(s) and in no way should be seen as an official policy of or interpretation by the SRTR or the U.S. Government.
Funding:
Drs. Reed, MacLennan, Shelton, and Locke are supported by the National Institute of Diabetes and Digestive and Kidney Diseases grant/award number: 5R01DK113980. The funder had no role in study design, data collection, analysis, reporting, or the decision to submit for publication.
Footnotes
Disclosures: None
Conflicts of interest:
The authors have no relevant financial disclosures to report.
Data sharing statement:
Data are available through the Scientific Registry of Transplant Recipients for bona fide research or analysis purposes per the Organ Procurement and Transplantation Network Final Rule section 121.11 and require the use of a signed data use agreement. https://www.srtr.org/requesting-srtr-data/data-requests/
References
- 1.Inker LA, Eneanya ND, Coresh J, et al. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race. N Engl J Med 2021;385:1737–49. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Delanaye P, Mariat C, Maillard N, Krzesinski JM, Cavalier E. Are the creatinine-based equations accurate to estimate glomerular filtration rate in African American populations? Clin J Am Soc Nephrol 2011;6:906–12. [DOI] [PubMed] [Google Scholar]
- 3.Diao JA, Wu GJ, Taylor HA, et al. Clinical Implications of Removing Race From Estimates of Kidney Function. JAMA 2021;325:184–6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Purnell TS, Luo X, Cooper LA, et al. Association of Race and Ethnicity With Live Donor Kidney Transplantation in the United States From 1995 to 2014. JAMA 2018;319:49–61. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Matas AJ, Ibrahim HN. The unjustified classification of kidney donors as patients with CKD: critique and recommendations. Clin J Am Soc Nephrol 2013;8:1406–13. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Lentine KL, Kasiske BL, Levey AS, et al. KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors. Transplantation 2017;101:S1–S109. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Vestergaard SV, Heide-Jorgensen U, Birn H, Christiansen CF. Effect of the Refitted Race-Free eGFR Formula on the CKD Prevalence and Mortality in the Danish Population. Clin J Am Soc Nephrol 2022. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group: KDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Inter Suppl: 1–150, 2013. Available at: https://kdigo.org/wp-content/uploads/2017/02/KDIGO_2012_CKD_GL.pdf. Accessed February 10, 2022. [Google Scholar]
- 9.Delanaye P, Jager KJ, Bokenkamp A, et al. CKD: A Call for an Age-Adapted Definition. J Am Soc Nephrol 2019;30:1785–805. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Garg N, Lentine KL, Inker LA, et al. The kidney evaluation of living kidney donor candidates: US practices in 2017. Am J Transplant 2020;20:3379–89. [DOI] [PubMed] [Google Scholar]
- 11.Muzaale AD, Massie AB, Wang MC, et al. Risk of end-stage renal disease following live kidney donation. JAMA 2014;311:579–86. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Lentine KL, Schnitzler MA, Xiao H, et al. Racial variation in medical outcomes among living kidney donors. N Engl J Med 2010;363:724–32. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Mandelbrot DA, Pavlakis M, Karp SJ, Johnson SR, Hanto DW, Rodrigue JR. Practices and barriers in long-term living kidney donor follow-up: a survey of U.S. transplant centers. Transplantation 2009;88:855–60. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
Data are available through the Scientific Registry of Transplant Recipients for bona fide research or analysis purposes per the Organ Procurement and Transplantation Network Final Rule section 121.11 and require the use of a signed data use agreement. https://www.srtr.org/requesting-srtr-data/data-requests/