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Keywords:

  • Black;
  • deceased donor;
  • dialysis;
  • donor;
  • elderly;
  • end-stage renal disease;
  • expanded criteria donor;
  • hepatitis C;
  • kidney transplant;
  • survival;
  • USRDS;
  • wait list

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Whether transplantation of deceased donor kidney allografts from donors with antibodies against hepatitis C virus (HCV) confers a survival advantage compared with remaining on the kidney transplant waiting list is not yet known. We studied 38,270 USRDS Medicare beneficiaries awaiting kidney transplantation who presented with end-stage renal disease from April 1, 1995 to July 31, 2000. Cox regression was used to compare the adjusted hazard ratios for death among recipients of kidneys from deceased donors, and donors with antibodies against hepatitis C (DHCV+), controlling for demographics and comorbidities. In comparison to staying on the waiting list, transplantation from DHCV+ was associated with improved survival among all patients (adjusted hazard ratio for death 0.76, 95% CI 0.60, 0.96). Of patients receiving DHCV+ kidneys, 52% were themselves hepatitis C antibody positive (HCV+), so outcomes associated with use of these grafts may have particular implications for HCV+ transplant candidates. Recommendations for use of DHCV+ kidneys may require analysis of data not currently collected from either dialysis or transplant patients. However, transplantation of DHCV+ kidneys is associated with improved patient survival compared to remaining wait-listed and dialysis dependent.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Transplantation of kidneys from deceased donors who are antibody positive for hepatitis C virus (DHCV+) is associated with greater recipient mortality than occurs with kidneys transplanted from deceased donors who are antibody negative for hepatitis C virus (DHCV−) (1,2). While use of DHCV+ kidneys for recipients who are themselves hepatitis C antibody positive (HCV+) is associated with an increased risk in late mortality compared to use of DHCV− kidneys (2,3), no previous analyses have compared survival after transplantation of DHCV+ kidneys with survival of wait-listed patients who remain on dialysis.

More than half of DHCV+ kidneys are transplanted in HCV+ recipients in the United States; risk factors associated with DHCV+ kidney transplantation include advanced donor and recipient age, African American race, and the possibility of a high rate of dialysis access complications (1,2,4). In addition, DHCV+ kidneys may be used with substantial variation between or within transplant centers depending on circumstances impossible to capture in reviewing single- or multi-center experiences. In order to determine any comparative trend in patient survival with DHCV+ kidney transplantation, we conducted a retrospective cohort study of the United States Renal Data System (USRDS). Our objective was to determine whether transplantation of DHCV+ kidneys was associated with a survival advantage or disadvantage for chronic dialysis patients receiving such a transplant compared to wait-listed patients remaining on dialysis.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Patients

We analyzed Medicare-eligible participants in the USRDS using a retrospective cohort design. Information on demographics, comorbidity, and laboratory data as available at the time of first treatment for end-stage renal disease (ESRD) was obtained from the Center for Medicare and Medicaid Studies Medical Evidence Form (CMS 2728), which has been used previously in clinical research (5). Specific files were merged as previously described (6). The USRDS researcher's agreement specifically prohibits patient contact or chart review.

Patients who initiated ESRD therapy from April 1,1995 to July 31, 2000 were included if they were later placed on the kidney transplant waiting list. Patients who were transplanted on or after May 31, 2001 (i.e. within 6 months of the end of the study) were censored at the date of transplant to avoid potential lags in reporting of outcomes. The United Network for Organ Sharing (UNOS) and the USRDS collect data with certain limitations regarding both donor and recipient (2). Recipients of organs other than kidneys were excluded. Hepatitis C virus (HCV) status is both determined and reported at the time of transplant for donor kidneys (presumably by ELISA for deceased donor kidneys due to current time constraints), and is reported but not necessarily performed at the time of transplant for recipients (reporting refers to any prior positive HCV testing). Information on HCV status is not routinely collected for patients on chronic maintenance dialysis through the USRDS database. Therefore, as a surrogate for HCV antibody status or infection prior to transplant, we used Medicare claims for the diagnosis and management of conditions related to HCV (acute hepatitis C with or without hepatic coma, International Classification of Diseases Code 9th edition (ICD-9), 070.41 or 070.51, or asymptomatic HCV carrier, code V026 or V026.2, respectively). For purposes of the study, we defined HCV seropositivity for all patients on the renal transplant waiting list as claims reported within 14 days of the date of listing for renal transplant (to allow for potential lagging of reporting) or at any time previously. Patients who did not have evidence of Medicare as primary payer after 14 days of the study start were excluded. Therefore, we limited the sample to patients enrolled on the kidney transplant waiting list on or after April 1, 1995 who had evidence of Medicare as primary payer 14 days after the date of listing or any time before. This determination of payer status was made using the PAYHIST files, based on Medicare billing records, introduced into the USRDS standard analysis files in 2002.

Outcomes

Our primary outcome measure was patient death from any cause. Other data from UNOS included donor type, recipient and donor age, race, gender, year of first dialysis session, recipient body mass index (BMI) at the date of first dialysis, diabetes and hypertension as comorbidities distinct from causes of ESRD, cardiovascular disease history, serum hematocrit and serum albumin at the time of first dialysis, and transplant center. We also analyzed Medicare billing records for claims related to dialysis access complications (Medicare Institutional Claims with ICD-9 codes 996.6x or 996.1x, occurring within 14 days of the date of listing as for HCV claims above). We collected outcomes and covariate data among recipients of expanded donor criteria kidneys (extended criteria donor, as defined by UNOS) (7) transplanted during the study period for use as an additional comparison group.

Survival Times

Time to death was defined as the time from the date of transplant listing until death, censored for loss to follow-up, the end of the study period, or receipt of any kidney transplant other than a solitary DHCV+ kidney. For comparison with all deceased donor kidneys, censoring was performed for receipt of living donor kidneys; for comparison with extended criteria donor kidneys, censoring was performed for receipt of any kidney other than from an extended criteria donor.

Statistical Analysis

All analyses were performed using SPSS 12.0™ (SPSS, Inc., Chicago, IL), with additional validation performed in Stata 8 (Intercooled version, College Station, TX). Files were merged and converted to SPSS files using DBMS/Copy (Conceptual Software, Houston, TX). Statistical significance was defined as p < 0.05. Univariate analysis was performed with χ2 testing for categorical variables and Student's t-test for continuous variables. Variables with p < 0.10 (rather than 0.05, to allow for possible negative confounding) in univariate analysis for a relationship with mortality were entered into multivariable analysis as covariates. Continuous variables were examined for outliers, and values thought to be clinically implausible were removed from analysis.

Cox regression non-proportional hazards analysis modeled the association between kidney transplantation as a discrete time-dependent variable (designated as 0 for all times prior to transplant, 1 for all times after transplant) with all-cause mortality, controlling for variables entered into the model as above. We did not remove patients from the category of listing for transplant if they were removed from this category at a later time, nor did we remove patients from the category of kidney transplant recipient if they later experienced graft loss, in intention-to-treat fashion. No interactions higher than two-way interactions were assessed.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Of 454,447 patients in the USRDS database who initiated ESRD therapy from April 1, 1995 to July 31, 2000, 53,369 were subsequently entered on the kidney transplant waiting list on or after April 1, 1995 and before August 1, 2000. Of these, 38,360 had evidence of Medicare as primary payer as defined. An additional 90 patients did not have information on survival status, leaving 38,270 patients in the study group. The mean date of first ESRD service was June 16, 1997. The mean date of listing for transplant was June 13, 1998, and the mean date of transplant was March 24, 1999. Characteristics of the study cohort including patients not transplanted as well as recipients of deceased donor kidneys and deceased donor DHCV+ kidneys, respectively, are shown in Table 1.

Table 1.  Characteristics of patients with ESRD with Medicare as primary payer when placed on the kidney transplant waiting list, who presented to ESRD from April 1, 1995—to July 31 20001
  All wait-listed patients Patients not transplanted P valueDeceased donor transplant recipients P valueDeceased donor DHCV+ transplant recipients P value
  1. Data given as the % of total (counts) or mean ± standard deviation.

  2. ESRD = End-stage renal disease; NOS = not otherwise specified.HCV = hepatitis C virus.

  3. DHCV+= donor hepatitis C virus antibody positive donor.

  4. 1Exclusions criteria as per methods: patients transplanted without preceding dialysis, or organs other than kidneys were excluded from analysis.

  5. 2history of condition or value at initiation of treatment for end stage renal disease

  6. 3For hepatitis C, defined as the date of the first of two ore more physician supplier claims or the first institutional claim for hepatitis C disease, either active or asymptomatic carrier, as defined in the Methods section, at or before the date of listing for transplant. For access complications, defined as the date of the first institutional claim for access complications, at or before the date of listing for transplant.

  7. P values are in comparison to all patients on the transplant waiting list, χ2 for categorical variables and Student's t-test for continuous variables, respectively.

N38,27017,044 16,495 389 
Male61.3% (23,443)59.9% (10,211)<0.00162.9% (10,437)<0.00175.3% (293)<0.001
African American30.4% (11,632)37.7% (6429)<0.00125.8 (4280)<0.00158.4% (227)<0.001
Diabetes as cause of ESRD35.3% (13,521)40% (6826)<0.00133.8 (5614)<0.00129.8% (116)0.002
Age (years)47.6 ± 13.850.1 ± 12.7<0.00146.3 ± 14.0<0.00151.2 ± 11.3<0.001
Variables from the Medical Evidence Form2
Body mass index (kg/m2)26.7 ± 6.227.3 ± 6.4<0.00126.2 ± 5.9<0.00126.0 ± 5.50.003
Serum albumin (gm/dL)3.4 ± 0.73.3 ± 0.70.033.4 ± 0.70.213.2 ± 0.70.66
Hematocrit (%)27.9 ± 5.727.7 ± 5.60.0927.9 ± 5.70.9628.2 ± 5.80.32
Hypertension73.9% (27,852)74.3 (12,670)<0.00173.2% (11,904)0.00677.0% (295)0.16
Congestive heart failure13.8% (5186)16.5% (2820)<0.00111.9% (1930)<0.00115.9% (61)0.22
Ischemic heart disease8.9% (3334)10.7% (1824)<0.0017.5% (1212)<0.0019.7% (37)0.58
 
Smoking history (Y/N)5.3% (1982)5.4% (918)0.125.4% (871)0.58.4% (32)*0.007
Hemodialysis (vs. peritoneal dialysis)80.5% (30,955)84.4% (14,378)*<0.00177.4% (12,834)<0.00186.1% (335)*<0.001
Peripheral vascular disease5.3% (1983)6.4% (1099)*<0.0014.6% (747)*<0.0014.4% (17)0.46
Medicare claims for HCV at the time of listing30.5% (180)0.5% (92)0.070.5% (80)0.755.4% (21)*<0.001
Recipient serology positive for HCV by UNOS (kidney transplant recipients only)NANANA4.3% (709)NA51.7% (201)* 
Medicare claims for access14.2% (5432)16.9% (2886)<0.00113.5% (2234)*0.00117.7% (69)0.042
 

Death rates for the study population stratified according to transplantation status, donor source (DHCV+ vs DHCV−), and recipient age disclose that unadjusted death rates were much higher for recipients of DHCV+ kidneys than for recipients of deceased donor kidneys generally (Table 2). However, among the entire study cohort, receipt of a DHCV+ kidney was independently associated with improved survival compared with remaining on the renal transplant waiting list, (adjusted hazard ratio 0.76, 95% CI, 0.60–0.96) when Cox regression analysis of factors associated with patient mortality was carried out, analyzing solitary deceased donor kidney transplantation as a discrete time-dependent variable (adjusted for age, race, cause of ESRD, year of first dialysis, presence of congestive heart failure, ischemic heart disease, peripheral vascular disease, serum albumin level, and Medicare Claims for access-related complications and HCV, Table 3). Transplantation of all deceased donor kidneys was also associated with a survival advantage after adjustment for multiple covariates, (adjusted hazard ratio 0.47, 95% CI 0.44–0.50). Among patients aged 65 years and older, transplant of deceased donor kidneys was also associated with a significant survival advantage, although magnitude of benefit was somewhat smaller (adjusted hazard ratio 0.59, 95% CI 0.51–0.68).

Table 2.  Patient death rates in patients with ESRD with Medicare as primary payer when placed on the kidney transplant waiting list, who presented to ESRD from April 1, 1995 –to July 31, 2000, followed through September 30, 2001
Categories N Deaths Follow-up time (years)Death rate per 100 Patient years at risk (95% CI)
  1. *Exclusions criteria as per Methods: patients transplanted without preceding dialysis, or organs other than kidneys were excluded from analysis. Patients who were transplanted in the last 6 months of the study were censored on the date of transplant.

Total cohort
All patients on the kidney transplant waiting list38,2706716116,3315.77 (5.63–5.91)
Patients not transplanted17,094475340,86111.63 (11.31–11.96)
Deceased donor recipients*16,595168959,4062.84 (2.71–2.98)
Deceased donor recipients of DHCV+ kidneys*3897212485.76 (4.57–7.26)
All patients on the kidney transplant waiting list age 65 years or older37201131983411.50 (10.85–12.19)
 
Deceased donor recipients age 65 years or older144329445756.43 (5.73–7.20)
Deceased donor recipients of DHCV+ kidneys* aged 65 years or older582515715.91 (10.75–23.54)
All patients on the kidney transplant waiting list with Medicare claims for HCV at the time of listing180344257.99 (5.71–11.12)
Table 3.  Cox regression analysis of the association of DHCV+ deceased donor kidney transplantation with mortality among patients placed on the kidney transplant waiting list with Medicare as primary payer, who presented with ESRD from April 1, 1995—to July 31, 2000
 P ValueAHR (95% CI)
  1. Multivariable analysis (by Cox non-proportional hazards regression) of factors associated with hospitalizations for obesity in patients placed on the kidney transplant waiting list, April 1, 1995 to July 31, 2000.

  2. 1Analysis for CR: censored living donor recipients at the time of transplant.

  3. 2The time-dependent covariate, for CR: 1 if deceased donor recipients from a donor antibody positive for hepatitis C (DHCV+), 0 else.

  4. 3Each type of donor kidney was evaluated in separate models.

  5. 4Defined as patients with multiple (more than one) Medicare claim for hepatitis C or access complications (as defined in the Methods section) after enrollment on the renal transplant waiting list.

  6. Only variables significant in the final model (p < 0.05 by Cox regression analysis) are shown. All models fit demographic variables (age, race, sex, year of listing) as well as a stepwise fit of all variables shown to be significantly associated with survival in previous studies. In addition, we also fitted access complications and claims for HCV at the time of listing. As shown above, access complications were significantly associated with mortality, while HCV claims at the time of listing were not (adjusted hazard ratio of 1.25 as shown above, but p value of 0.2).

  7. AHR = adjusted hazard ratio for mortality, CHF = congestive heart failure.

  8. 95% CI = 95% confidence intervals.

  9. ESRD = End-stage renal disease, CHF = cardiac failure, PVD = peripheral vascular disease listed as a comorbidity on form 2728, BMI = body mass index.

Type of donor kidney1
 Kidney transplantation from a DHCV+ donor2 (vs. remaining on dialysis, censoring for all other transplants)0.0250.76 (0.60–0.96)
 Kidney transplantation from a deceased donor3 (vs. remaining on dialysis, censoring for all other transplants)<0.0010.47 (0.44–0.50)
Other factors
 Age (per increase in year)<0.00011.03 (1.02–1.04)
 Year of listing (per more recent year)<0.00010.84 (0.82–0.86)
 Diabetes as cause of ESRD (vs. non-diabetics)<0.00011.98 (1.89–2.07)
 African American recipient (vs. all other races)<0.00010.71 (0.68–0.75)
 Years of dialysis prior to transplant (per year)<0.0011.12 (1.09–1.14)
Variables from Medical Evidence Form 2728
 PVD (vs. absent)<0.00011.21 (1.12–1.30)
 CHF (vs. absent)<0.00011.21 (1.15–1.28)
 Quartiles of serum albumin (per higher quartile)<0.00010.87 (0.81–0.93)
 BMI (per kg/m2)0.0030.99 (0.98–0.99)
 Smoking (vs. absent)<0.00011.34 (1.22–1.46)
 Access complications at the time of listing4<0.00011.22 (1.14–1.31)
 HCV claims at time of listing40.201.25 (0.89–1.76)
 N in model36,717 

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

The present analysis of Medicare beneficiaries enrolled on the kidney transplant waiting list indicates that transplantation from a hepatitis C positive donor (DHCV+) was associated with improved survival compared to remaining on dialysis. The benefit of transplantation with a DHCV+ kidney was not as substantial as transplantation with all deceased donor kidneys, adjusted for other factors known to be associated with survival. This benefit of DHCV+ kidneys was shown only in adjusted, not unadjusted analysis, because of the confounding of allocation of DHCV+ kidneys by several factors, most notably older recipient age, as well as unknown factors that may relate to subsequent survival. Unfortunately, we could not confirm this effect in HCV+ recipients, the subgroup analysis of greatest interest, due to the very small numbers of dialysis patients who had Medicare claims for HCV at the time of listing. Among dialysis patients, HCV testing is voluntary and is not the subject of routine surveillance, in contrast to HIV and hepatitis B viruses (8).

Use of Medicare claims for HCV filed at the time of listing preserved the temporal relationships necessary for valid survival analysis, but does not account for the large proportion of dialysis patients who develop positive HCV serology while on dialysis. According to the recent DOPPS (a prospective observational) study, the prevalence of HCV among American dialysis patients at the start of dialysis was 7.3%, while the prevalence of HCV among those who had been on dialysis for 10 years of more was 22.5%, and was 39% for those who had been on dialysis for 15 years or more (9). Comparable trends have also been reported from European regional studies (10). While such increases in HCV positivity may reflect period effects as well as duration effects (i.e. patients on dialysis 10 years ago were much more likely to receive blood transfusions or be exposed to other HCV risk factors than patients are currently), long-term dialysis care is significantly associated with higher rates of HCV seroconversion.

It has been generally thought that DHCV+ kidneys are safe to use in HCV+ and elderly recipients, due to latency of clinical liver disease after transmission of HCV infection as well as the diminished life expectancy of elderly recipients (11). Receipt of a DHCV+ kidney by elderly wait-listed patients offered no survival benefit compared to remaining on dialysis in this study, and was associated with higher mortality than DHCV− kidneys. Current recommendations discourage use of DHCV+ kidneys in elderly recipients who are HCV negative (12), and the present study cannot address this specific issue. However, dialysis patients with a negative result for HCV testing at one point in time may not be retested later, even before a renal transplant. On the other hand, the development of HCV seroconversion, even many years after listing, may affect whether a patient is offered a DHCV+ kidney. Therefore, for the data sources we used, true recipient HCV status may be insensitive, and it may not be possible to fully define the impact of DHCV+ kidneys on survival of HCV+ dialysis patients.

The present study has several limitations in addition to those of recipient HCV status. A key to the validity of the present analysis is whether the comparison group of patients who did not receive DHCV+ kidneys is a reasonably equivalent group. The methods we have used are the same other investigators have used previously in assessing the relative survival of transplantation compared with remaining on the waiting list (13). The report of Wolfe et al. (13) adjusted only for age, race, gender, transplant center, and cause of renal disease, and assumed that patients who were listed for transplant were otherwise equivalent. However, these assumptions may not be accurate in terms of selection of patients to receive a DHCV+ kidney. Therefore, we also adjusted for comorbid conditions in CMS Form 2728 as well as access-related complications. This is an additional step that, to our knowledge, others have not considered (6). In addition, the relative survival benefit of transplantation with DHCV+ kidneys could be either overestimated or underestimated in this analysis due to patient selection factors not captured in data reporting. Those factors associated with DHCV+ transplantation and the high mortality associated with DHCV+ transplantation in unadjusted analysis (Table 2, equivalent to mortality of all wait-listed patients) emphasize that patients' selection for DHCV+ kidneys is quite different than for recipients of DHCV− kidney transplants, and such differences may be impossible to define in any analysis. Details on the use of antiviral therapy, treatment response rates and results of more definitive diagnostic tests such as PCR, RNA, or liver biopsy results, were simply not available. These findings should be verified with more cases in the future, especially for HCV+ recipients, and also with longer follow-up, given the relatively short follow-up post-transplant in the present study.

In conclusion, while the use of DHCV+ kidneys is associated with an increased risk of mortality compared to use of DHCV− kidneys (1,2), the present study found that use of DHCV+ kidneys is associated with improved survival compared with remaining on dialysis. Since most DHCV+ kidneys are given to recipients who are themselves HCV+, these implications may primarily apply to HCV+ recipients. The present study's findings are thus consistent with current recommendations that DHCV+ kidneys can be used for HCV+ recipients, but probably should be avoided for HCV− recipients (12). However, allocation of DHCV+ kidneys is presently center-specific and guidelines for using these organs may require more information than is presently reported to UNOS, CMS or the USRDS. Clearly, some patients benefit from transplantation of DHCV+ kidneys, yet it may not be timely to suggest that such organs should be given to non-selected groups of patients.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Supported in part by a grant from the National Institute of Diabetes, Digestive, and Kidney, Diseases K25-DK-02916-01, Mark A. Schnitzler, Ph.D., P. I.

Funding Sources: Dr. Lentine is a recipient of the 2004 Clinical Scientist in Nephrology Award from the American kidney fund.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References
  • 1
    Bucci JR, Matsumoto CS, Swanson SJ et al. Donor hepatitis C seropositivity: Clinical correlates and effect on early graft and patient survival in adult cadaveric donor kidney transplantation. J Am Soc Nephrol 2002; 13: 29742982.
  • 2
    Abbott KC, Bucci JR, Matsumoto CS et al. Hepatitis C and kidney transplantation in the era of modern immunosuppression. J Am Soc Nephrol 2003; 14: 29082918.
  • 3
    Woodside KJ, Ishihara K, Theisen JE et al. Use of kidneys from hepatitis C seropositive donors shortens waitlist time but does not alter one-yr outcome. Clin Transplant 2003; 17: 433437.
  • 4
    Ojo AO, Hanson JA, Meier-Kriesche H et al. Survival in recipients of marginal cadaveric donor kidneys compared with other recipients and wait-listed transplant candidates. J Am Soc Nephrol 2001; 12: 589597.
  • 5
    Longenecker JC, Coresh J, Klag MJ et al. Validation of comorbid conditions on the end-stage kidneydisease medical evidence report: the CHOICE study. Choices for healthy outcomes in caring for ESRD. J Am Soc Nephrol 2000; 11: 520529.
  • 6
    Glanton CW, Kao TC, Cruess D, Agodoa LY, Abbott KC. Impact of renal transplantation on survival in end-stage renal disease patients with elevated body mass index. Kidney Int 2003; 63: 647653.
  • 7
    Hepatitis and the Renal Transplant Recipient, Brian J. Pereira, MD, from http://www.unos.org/shareddownloadables/ExpandedCriteriaDonorKidneyPolicyBrochureProf10072002Final.pdf accessed 11/01/2003.
  • 8
    Natov SN, Pereira BJ. Routine serologic testing for hepatitis C virus infection should be instituted among dialysis patients. Semin Dial 2000; 13: 3938.
  • 9
    Fissell RB, Bragg-Gresham JL, Woods JD et al. Patterns of hepatitis C prevalence and seroconversion in hemodialysis units from three continents: The DOPPS. Kidney Int 2004; 65: 23352342.
  • 10
    Espinosa M, Martn-Malo A, Ojeda R et al. Marked reduction in the prevalence of hepatitis C virus infection in hemodialysis patients: Causes and consequences. Am J Kidney Dis 2004; 43: 6859.
  • 11
    Ojo AO, Hanson JA, Meier-Kriesche H et al. Survival in recipients of marginal cadaveric donor kidneys compared with other recipients and wait-listed transplant candidates. J Am Soc Nephrol 2001; 12: 589597.
  • 12
  • 13
    Wolfe RA, Ashby VB, Milford EL et al. Comparison of mortality in all patients on dialysis, patients on dialysis awaiting transplantation, and recipients of a first cadaveric transplant. N Engl J Med 1999; 341: 17251730.