SEARCH

SEARCH BY CITATION

Opelz and colleagues were among the first to recognize that black Americans receiving kidney transplants fared worse than other racial groups (1). Since then, the relationship between ethnicity and renal transplantation has been accepted as a worthy subject for scholarly inquiry in the United States. Despite the inherent difficulties in defining such indistinct, ambiguous designations as race and ethnicity (indeed, for the purposes of this editorial, these words will be used interchangeably), substantial data exist (2,3). Worldwide statistics regarding these issues are less accessible, at least in part reflecting variability in data collection (4). Most studies have addressed race as an immutable demographic characteristic, much like age, gender, or degree of presensitization. As summarized in a recent review, these data indicate that African Americans are at enhanced risk for end-stage renal disease (ESRD), with limited access to and lowered expectations for successful transplantation when compared to other ethnic groups (5,6). These discrepancies do not appear to be the result of intentional discrimination, but rather reflect a complex interplay of genetic, cultural, and socioeconomic variables. Notwithstanding their origin, the accumulated data seem sufficient to warrant the next step: implementing remedies where they can be applied, particularly regarding access to transplantation.

Unfortunately, seeking to reduce ethnic disparities may raise new questions. First, while it may be reasonable to utilize racial categories in analyzing statistics, applying these same categories to implement solutions is potentially more hazardous. Granting specific preferences to members of a specific ethnic group requires precision in defining race beyond what is currently available. Crafting policy to determine who qualifies for preference, and who does not, may be neither scientifically possible nor socially desirable, and may implicitly foster ongoing discord (7,8). Second, while we know a great deal about black Americans with kidney disease, the face of minorities in America is rapidly changing. Granted, blacks comprise by far the largest identifiable ethnic minority in the ESRD population (3). But, native Americans are also at increased risk of ESRD relative to Caucasians, and face many of the same problems with transplantation as blacks. In addition, our knowledge regarding hypertension, renal disease and access to transplantation for the most rapidly growing minority population (those of Hispanic ethnicity) is in its infancy. Any proposed solution must be fair, unbiased, and broadly applicable.

Given these competing demands and a rapidly changing environment, how are we as transplant professionals to respond creatively to questions of equal access? While ethnic discrepancies become evident very early in the transplant process (9), our impact on referral practices is likely to be somewhat limited. Nonetheless, Department of Health and Human Services regulations mandating evaluation of ESRD patients for transplantation provide a strong legal underpinning for equity in the process. Additional improvement will require earlier identification and referral of those with chronic kidney disease to knowledgeable nephrologists, along with better education of potential donors and recipients regarding the benefits of transplantation. Once an evaluated patient is deemed to be a suitable candidate, however, he or she must be assured of an equitable opportunity to receive a kidney transplant in a timely fashion, limited only by the evolving boundaries of medical necessity.

Under the current United Network for Organ Sharing (UNOS) allocation system, black (and native American) transplant candidates are significantly less likely to receive a cadaveric kidney than Caucasians, while waiting twice as long for transplantation (6). At least some of this discrepancy is due to unalterable factors that adversely impact the success of a transplant (e.g. blacks are more likely to be presensitized). However, even nonsensitized African Americans are disadvantaged by the current system, a fact attributable at least in part to variables that play a major role in allocation despite a rapidly diminishing impact on transplant outcomes.

Most blacks with ESRD are ABO types O and B, attributes that define candidates destined to wait significantly longer for cadaveric kidneys (6,10). As noted by Nelson and colleagues in this issue of AJT, it is now possible to better characterize blood groups, such that A2 and A2B organs might be made available for B candidates, 65% of whom are African American (2,11). In the Midwest Transplant Network, utilization of an allocation algorithm incorporating this approach increased transplantation among B candidates by a third, did not significantly reduce access for those with ABO type A, and resulted in excellent allograft survival. While technically a bit more demanding (with comprehensive screening of donors and surveillance of potential recipients for anti-A titers), expanding the Kansas City variance nationally is a race-neutral remedy that increases equity within the system by diminishing differences in waiting time among blood groups.

Since its inception, HLA typing has been used to define similarity between donor and recipient. The first national allocation system, an outgrowth of the National Organ Transplant Act of 1984, reflected the importance of HLA matching in those days of relatively ineffective immunosuppression (12). However, recent dramatic advances in transplantation therapeutics, while not eliminating the impact of HLA on outcome, have greatly reduced its importance relative to other variables (13). In cadaveric transplantation, it now appears that only the complete absence of HLA mismatches confers a significant survival benefit (14). Currently, the impact of an HLA-based allocation system is to offer rapid transplantation to those with common antigens, while reducing access for ESRD patients with uncommon HLA specificities (notably minorities). An extensive UNOS study confirms these findings: by virtue of inheriting HLA antigens dissimilar to those of the donor pool, black transplant candidates seeking cadaveric kidneys wait longer and receive fewer transplants than Caucasians, regardless of their place of residence. (Figure 1) (15). It seems reasonable to assume that other less identifiable patients with uncommon HLA specificities might be equally disadvantaged.

image

Figure 1. Comparison of percentages of transplant candidates receiving cadaveric kidneys, by ethnicity and individual organ procurement organization (OPO), at 1 and 3 years after wait listing. All kidney registrations were added to the waiting list between 1994 and 99. Diamonds represent individual OPOs; the open circles represent the nation as a whole. (Data from United Network for Organ Sharing, Richmond, VA) (Reference 13, Exhibit J).

Download figure to PowerPoint

  • Given the remarkably improved outcomes and unprecedented expansion of the kidney waiting list, it is no longer possible to justify the disparity fostered by HLA-based allocation with its relatively meager benefit in immunologic graft survival. A study of kidney allocation in Texas revealed that elimination of HLA-based local allocation reduced racial differences in access and waiting time (16). A recently published national model indicated that reducing reliance on ABO identity and HLA matching might increase minority access to transplantation by as much as 15% (5). In August, after extensive study, the UNOS kidney/pancreas and minority affairs committees jointly proposed amending the current algorithm by deleting HLA criteria from local allocation. This proposal, which would maintain national sharing of HLA-matched kidneys, is currently available for public comment at the UNOS website (http://www.unos.org) (15). These proposed changes in the allocation process seem another reasonable, race-neutral approach that recognizes the changing empiricism of renal transplantation, is unlikely to threaten medical efficiency (in terms of graft survival), and moves toward more equitable access for all.

With current data documenting the overwhelming benefits of kidney transplantation relative to chronic dialysis, our responsibility as a community is to ensure that every suitable transplant candidate has a reasonable chance to receive a life-sustaining kidney. The best solution, to which we must remain thoroughly committed, is to increase the supply of kidneys available for transplantation. In the meantime, though addressing minority issues in transplantation policies may require delving into uncomfortable scientific and social controversies, to do otherwise is to betray the trust given us by patients and society.

References

  1. Top of page
  2. References
  • 1
    Opelz G, Mickey MR, Terasaki PI. Influence of race on kidney transplant survival. Transplant Proc 1977; 9: 137142.
  • 2
    United Network for Organ Sharing. 2000 Annual Report of the U.S. Scientific Registry of Transplant Recipients and the Organ Procurement and Transplantation Network. UNOS, Richmond, VA, USA; 2001.
  • 3
    United States Renal Data System. Excerpts from the USRDS 2000 Annual Data Report. Am J Kidney Dis 2000; 36 (Suppl. 2): S15S181.
  • 4
    ANON. ESRD throughout the world. morbidity, mortality, and quality of life. Kidney Int 2000; 57 (Suppl. 74): S1S143.
  • 5
    Wolfe RA, Ashby VB, Milford EL, Bloembergen WE, Agodoa LYC, Held PJ et al. Differences in access to cadaveric renal transplantation in the United States. Am J Kidney Dis 2000; 36: 10251033.
  • 6
    Young CJ, Gaston RS. Renal transplantation in black Americans. N Engl J Med 2000; 343: 15451552.
  • 7
    Omi MA. The changing meaning of race. In: Smelser N, Wilson WJ, Mitchell F, editors. America Becoming: Racial Trends, Their Consequences. Washington D.C.: National Academy Press; 2001. p. 243263.
  • 8
    Oppenheimer GM. Paradigm lost. race, ethnicity, and the search for a new population taxonomy. Am J Public Health 2001; 91: 10491055.
  • 9
    Epstein AM, Ayanian JZ, Keogh JH, Noonan SJ, Armistead N, Cleary PD et al. Racial disparities in access to renal transplantation: clinically appropriate or due to underuse or overuse? N Engl J Med 2000; 343: 15371544.
  • 10
    Kallich JD, Adams JL, Barton PL, Spritzer KL. Access to cadaveric kidney transplantation. Los Angeles: Rand/UCLA/Harvard Center for Health Care Financing Policy Research; 1993.
  • 11
    Nelson PW, Shield CF, Muruve NA, Murillo D, Warady BA, Aeder MI et al. Increased access to transplantation for blood group B cadaveric waiting list candidates by using A2 kidneys: time for a new national system? Am J Transplantation 2001; 2: 9499.
  • 12
    Institute of Medicine (US). Kidney Failure and the Federal Government. Washington, DC: National Academy Press; 1991.
  • 13
    Zenios SA, Wein LM, Chertow GM. Evidence-based organ allocation. Am J Med 1999; 107: 5261.
  • 14
    Takemoto SK, Terasaki PI, Gjertson DW, Cecka JM. Twelve years' experience with national sharing of HLA-matched cadaveric kidneys for transplantation. N Engl J Med 2000; 343: 10781084.
  • 15
    United Network for Organ Sharing. Proposed Amended UNOS Policy 3.5.9.2 (Quality of Antigen Mismatch), Richmond, VA, USA; 20018/17/01.
  • 16
    Van Buren CT, Shafer T. Does kidney allocation based on HLA matching adversely affect minority access to transplantation? (Abstract). Am J Transplantation 2001; 1 (Suppl. 1): 357.