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Correction to Hariharan et al., N Engl J Med 342(9):605-612 March 2, 2000.

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Volume 342:1837-1838 June 15, 2000 Number 24
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Improved Graft Survival after Renal Transplantation in the United States, 1988 to 1996

 

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To the Editor: It was heartening to learn that the outcome of kidney transplantation has improved since 1988, as reported by Hariharan and colleagues (March 2 issue).1 When one discusses treatment options with a patient, however, it is frequently helpful to estimate the chance that a kidney graft will be functioning 5 or 10 years after surgery. With other diseases, such as cancer and heart disease, data on survival at five years, determined from the date of the intervention, are widely available. Although appropriate scientifically, the approach that Hariharan and colleagues used — analysis of graft survival at one year and then derivation of the half-life of the graft, with events during the first year excluded — does not readily provide such information.

On the basis of the data before censoring, reported by Hariharan and colleagues in Table 2 of their article, we estimate that the survival rate at five years for cadaveric grafts transplanted in 1988 was approximately 56 percent. In contrast, the projected five-year survival rate for cadaveric grafts transplanted in 1995 was approximately 74 percent. Thus, the modest improvement in long-term graft survival (approximately 6 percent at five years) shown in Figure 2 of the article translates into a large improvement in long-term survival (an absolute difference of 18 percent), when differences during the first year are factored into the analysis.


Chirag Parikh, M.D.
David H. Ellison, M.D.
University of Colorado Health Sciences Center
Denver, CO 80220

References

  1. Hariharan S, Johnson CP, Bresnahan BA, Taranto SE, McIntosh MJ, Stablein D. Improved graft survival after renal transplantation in the United States, 1988 to 1996. N Engl J Med 2000;342:605-612. [Free Full Text]
 
To the Editor: We were pleased to see that long-term renal graft survival increased from 1988 to 1996 in the United States. However, a few points in the report by Hariharan et al. need clarification. It would have been useful if they had stated the percentage of patients who were receiving cyclosporine each year. Without this information, it is difficult to attribute any improvement in short-term or long-term graft survival to treatment with cyclosporine, since the drug was being used even in 1988. Second, there was a substantial decrease in the mean value for serum panel-reactive antibody in the recipients during the study period. Was the decrease due to a decreased rate of blood transfusion, and to what extent does the decrease explain the improvement in long-term graft survival? Third, the authors state, "The projected half-life for transplants in nonblack recipients increased from 9.1 years to 13.3 years from 1988 to 1995, an increase of 46 percent. The corresponding values for transplants in blacks were 5.1 years and 7.2 years, an increase of 41 percent." However, according to Table 2 of the article, the overall projected half-life of grafts from living donors (i.e., in blacks and nonblacks) transplanted in 1995 was 21.6 years, and the overall half-life of cadaveric grafts was 13.8 years. Even if only patients with cadaveric transplants are considered, how could the projected half-life in 1995 be 13.3 years for whites and 7.2 years for blacks but 13.8 years overall?


Ramin Sam, M.D.
David J. Leehey, M.D.
Loyola University Medical Center
Maywood, IL 60153

 
The authors reply:

To the Editor: Parikh and Ellison correctly note that from the patient's perspective, improvement in the short-term and long-term survival of renal transplants is additive and directly affects the prognosis.

We found that there has been steady improvement in the survival of renal transplants since the introduction of cyclosporine in the 1980s. Over 90 percent of the 1988 cohort received cyclosporine, and therefore the improved outcomes in later cohorts could be related to changes in doses or timing.1 However, the improvement is probably not related to cyclosporine alone. The causes of this improvement cannot be pinpointed, but they include a reduction in episodes of acute rejection and improvements in the control of hypertension and in the prevention and management of infections. The decrease in panel-reactive antibodies is probably due to a reduction in the transfusion rate (15 percent with more than 10 prior transfusions in 1988 vs. less than 4 percent after 1992), a decrease that is correlated with the introduction of erythropoietin.

Sam and Leehey raise a question about discrepancies between the text and Table 2 of our article with respect to the improvement in the projected half-life of transplants in blacks, nonblacks, and all recipients. The projected half-life values given in the text (7.2 years for blacks and 13.3 years for nonblacks) were for 1994, not 1995; the value of 11.0 years for all recipients of cadaveric transplants, shown in Table 2, is correct.


Sundaram Hariharan, M.D.
Medical College of Wisconsin
Milwaukee, WI 53226


Donald Stablein, Ph.D.
EMMES Corporation
Potomac, MD 20854

References

  1. Tejani A, Sullivan EK. Higher maintenance cyclosporine dose decreases the risk of graft failure in North American children: a report of the North American Pediatric Renal Transplant Cooperative Study. J Am Soc Nephrol 1996;7:550-555. [Abstract]
 


 

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