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Obese kidney transplant recipients have good outcomes
Obese Kidney Transplant Recipients Have Good Outcomes R.J. Howard, V.B. Thai, P.R. Patton, A.W. Hemming, A.I. Reed, W.J. Van der Werf, S. Fujita, J.L. Karlix, and J.C. Scornik
O
BESE kidney transplant recipients have increased delayed graft function,1– 4 increased immunologic graft loss,5 decreased graft survival,1–3,5–7 decreased patient survival,1,6,8 and increased posttransplant complications.1,2,6,8 Obesity is frequently determined using the bodymass index (BMI) (weight in kilograms/height in meters2). We formerly required obese patients to lose weight before being put on the kidney waiting list. A subsequent study showed that only 10% actually lost weight and only 5% lost enough weight to be listed. PATIENTS AND METHODS Between January 1, 1990, and December 31, 1999, we performed 833 first kidney transplants in patients older than 18 years at the University of Florida. Patients were divided into three groups for analysis: group 1, BMI ⬍25 (normal); group 2, BMI ⱖ25 and ⬍30 (overweight); and group 3, BMI ⱖ30 (obese). The BMIs for the patients in this study ranged from 14 to 42. The numbers of patients in the groups were: group 1, 457; group 2, 278; and group 3, 98. Patients were compared for graft and patient survival and for posttransplant complications. We used prednisone, azathioprine, and cyclosporine (Neoral) for immunosuppression. We did not use induction therapy. Actuarial survival was calculated by the Kaplan-Meier method. Survival curves were compared with the log-rank test. The chisquare test was used to compare nonparametric data among the groups. A P value of ⬍.05 was considered significant.
RESULTS
There were no differences in patient demographic variables with respect to age, number of patients with diabetes mellitus, or organ source. There were more male patients in the mildly obese group (P ⬍ .05), and more AfricanAmericans in the obese group (P ⬍ .001). One year after transplantation, cadaveric graft survival was 90% for group 1, 92% for group 2, and 88% for group 3 (Table 1) (P ⬎ .05). Delayed graft function (DGF) was defined as the need for dialysis in the first week following transplantation. Among cadaveric donors, the incidence of DGF was 26.7% for group 1, 31.0% for group 2, and 36.1% for group 3 (P ⬎ .05). Death with function was the most common cause of graft loss. Death with function was significantly less common in group 3 (obese patients) than patients in groups 1 or 2.
Table 1. Graft and Patient Survival Percent Survival (%) ⬍25 (n ⫽ 457)
BMI
Cadaver donor Graft survival 1 year 5 years Patient survival 1 year 5 years Living donors Graft survival 1 year 5 years Patient survival 1 year 5 years
ⱖ25 and ⬍30 (n ⫽ 278)
ⱖ30 (n ⫽ 98)
P
90 74
92 78
88 75
NS NS
95 85
94 83
95 81
NS NS
97 85
96 89
100 86
NS NS
100 96
98 91
100 100
NS NS
Abbreviations: BMI, body mass index; NS, not significant.
There were no differences in the other causes of graft loss among the three groups. There were no differences in the causes of death among the three groups. The most common causes of death were cardiac disease, infection, cancer, and stroke. Significantly more patients in group 3 developed posttransplant diabetes mellitus than in groups 1 or 2 (P ⬍ .001). DISCUSSION
Unlike several previous reports,1– 8 our results show little difference in the outcomes of renal transplant recipients based on BMI. Obesity does not seem to impose an undue risk for kidney transplantation. That it is difficult for obese patients with end-stage renal disease to lose weight by decreasing energy intake or increasing energy expenditure helps to explain why so few From the Department of Surgery, University of Florida College of Medicine, Gainesville, Florida. Address reprint requests to Richard J. Howard, MD, PhD, Department of Surgery, University of Florida College of Medicine, PO Box 100286, Gainesville, FL 32610-0286.
0041-1345/01/$–see front matter PII S0041-1345(01)02474-5
© 2001 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
3420
Transplantation Proceedings, 33, 3420–3421 (2001)
OBESE KIDNEY TX RECIPIENTS
patients become transplant candidates if they are expected to lose weight first. We were disturbed when we found that patients who were required to lose weight before transplantation seldom lost weight, and even if they did lose some weight they almost never lost enough to be transplanted with the stringent weight limits we formerly used. Because so few patients were able to lose weight so they could get transplanted, we increased our weight limit to a BMI of 35. This limit, too, was somewhat arbitrary. But it was also based on reports showing obese patients did not do as well as nonobese patients. Despite our own stated limit of a BMI of 35, nevertheless, 12 patients had a BMI ⬎35. Even if obese patients do have a somewhat poorer outcome (something we did not find), perhaps they should be considered high-risk patients. We believe the results in obese patients are comparable to those in nonobese patients and that weight alone should not be a barrier to transplantation.
3421
REFERENCES 1. Holley JL, Shapiro R, Lopatin WB, et al: Transplantation 49:387, 1990 2. Pirsch JD, Armbrust MJ, Knechtle SJ, et al: Transplantation 59:631, 1995 3. Feldman HI, Faxio I, Roth D, et al: J Am Soc Nephrol 7:151, 1996 4. Drafts HH, Anjum MR, Wynn JJ, et al: Clin Transplant 11:493, 1887 5. Gill IS, Hodge EE, Novick AC, et al: Transplant Proc 25:1047, 1993 6. Meier-Kriesche HU, Vaghela M, Thambuganipalle R, et al: Transplantation 68:1294, 1999 7. Blu ¨mke M, Keller E, Eble F, et al: Transplant Proc 25:2618, 1993 8. Modlin CS, Flechner SM, Goormastic M, et al: Transplantation 64:599, 1997
O
BESE kidney transplant recipients have increased delayed graft function,1– 4 increased immunologic graft loss,5 decreased graft survival,1–3,5–7 decreased patient survival,1,6,8 and increased posttransplant complications.1,2,6,8 Obesity is frequently determined using the bodymass index (BMI) (weight in kilograms/height in meters2). We formerly required obese patients to lose weight before being put on the kidney waiting list. A subsequent study showed that only 10% actually lost weight and only 5% lost enough weight to be listed. PATIENTS AND METHODS Between January 1, 1990, and December 31, 1999, we performed 833 first kidney transplants in patients older than 18 years at the University of Florida. Patients were divided into three groups for analysis: group 1, BMI ⬍25 (normal); group 2, BMI ⱖ25 and ⬍30 (overweight); and group 3, BMI ⱖ30 (obese). The BMIs for the patients in this study ranged from 14 to 42. The numbers of patients in the groups were: group 1, 457; group 2, 278; and group 3, 98. Patients were compared for graft and patient survival and for posttransplant complications. We used prednisone, azathioprine, and cyclosporine (Neoral) for immunosuppression. We did not use induction therapy. Actuarial survival was calculated by the Kaplan-Meier method. Survival curves were compared with the log-rank test. The chisquare test was used to compare nonparametric data among the groups. A P value of ⬍.05 was considered significant.
RESULTS
There were no differences in patient demographic variables with respect to age, number of patients with diabetes mellitus, or organ source. There were more male patients in the mildly obese group (P ⬍ .05), and more AfricanAmericans in the obese group (P ⬍ .001). One year after transplantation, cadaveric graft survival was 90% for group 1, 92% for group 2, and 88% for group 3 (Table 1) (P ⬎ .05). Delayed graft function (DGF) was defined as the need for dialysis in the first week following transplantation. Among cadaveric donors, the incidence of DGF was 26.7% for group 1, 31.0% for group 2, and 36.1% for group 3 (P ⬎ .05). Death with function was the most common cause of graft loss. Death with function was significantly less common in group 3 (obese patients) than patients in groups 1 or 2.
Table 1. Graft and Patient Survival Percent Survival (%) ⬍25 (n ⫽ 457)
BMI
Cadaver donor Graft survival 1 year 5 years Patient survival 1 year 5 years Living donors Graft survival 1 year 5 years Patient survival 1 year 5 years
ⱖ25 and ⬍30 (n ⫽ 278)
ⱖ30 (n ⫽ 98)
P
90 74
92 78
88 75
NS NS
95 85
94 83
95 81
NS NS
97 85
96 89
100 86
NS NS
100 96
98 91
100 100
NS NS
Abbreviations: BMI, body mass index; NS, not significant.
There were no differences in the other causes of graft loss among the three groups. There were no differences in the causes of death among the three groups. The most common causes of death were cardiac disease, infection, cancer, and stroke. Significantly more patients in group 3 developed posttransplant diabetes mellitus than in groups 1 or 2 (P ⬍ .001). DISCUSSION
Unlike several previous reports,1– 8 our results show little difference in the outcomes of renal transplant recipients based on BMI. Obesity does not seem to impose an undue risk for kidney transplantation. That it is difficult for obese patients with end-stage renal disease to lose weight by decreasing energy intake or increasing energy expenditure helps to explain why so few From the Department of Surgery, University of Florida College of Medicine, Gainesville, Florida. Address reprint requests to Richard J. Howard, MD, PhD, Department of Surgery, University of Florida College of Medicine, PO Box 100286, Gainesville, FL 32610-0286.
0041-1345/01/$–see front matter PII S0041-1345(01)02474-5
© 2001 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
3420
Transplantation Proceedings, 33, 3420–3421 (2001)
OBESE KIDNEY TX RECIPIENTS
patients become transplant candidates if they are expected to lose weight first. We were disturbed when we found that patients who were required to lose weight before transplantation seldom lost weight, and even if they did lose some weight they almost never lost enough to be transplanted with the stringent weight limits we formerly used. Because so few patients were able to lose weight so they could get transplanted, we increased our weight limit to a BMI of 35. This limit, too, was somewhat arbitrary. But it was also based on reports showing obese patients did not do as well as nonobese patients. Despite our own stated limit of a BMI of 35, nevertheless, 12 patients had a BMI ⬎35. Even if obese patients do have a somewhat poorer outcome (something we did not find), perhaps they should be considered high-risk patients. We believe the results in obese patients are comparable to those in nonobese patients and that weight alone should not be a barrier to transplantation.
3421
REFERENCES 1. Holley JL, Shapiro R, Lopatin WB, et al: Transplantation 49:387, 1990 2. Pirsch JD, Armbrust MJ, Knechtle SJ, et al: Transplantation 59:631, 1995 3. Feldman HI, Faxio I, Roth D, et al: J Am Soc Nephrol 7:151, 1996 4. Drafts HH, Anjum MR, Wynn JJ, et al: Clin Transplant 11:493, 1887 5. Gill IS, Hodge EE, Novick AC, et al: Transplant Proc 25:1047, 1993 6. Meier-Kriesche HU, Vaghela M, Thambuganipalle R, et al: Transplantation 68:1294, 1999 7. Blu ¨mke M, Keller E, Eble F, et al: Transplant Proc 25:2618, 1993 8. Modlin CS, Flechner SM, Goormastic M, et al: Transplantation 64:599, 1997