Morbid Obesity Is Not an Independent Predictor of Graft Failure or Patient Mortality After Kidney Transplantation

ORIGINAL RESEARCH

Morbid Obesity Is Not an Independent Predictor of Graft Failure or Patient Mortality After Kidney Transplantation Daniel Pieloch, MS, RD,* Viktor Dombrovskiy, MD, PhD, MPH,† Adena J. Osband, MD,*,† Jonathan Lebowitz, MD,*,‡ and David A. Laskow, MD*,† Objective: Obesity is often an absolute contraindication to kidney transplant, but an internal analysis of our center’s recipients suggests that not all obese populations exhibit poor outcomes. We used national data to compare outcomes in select groups of morbidly obese and normal-weight recipients after kidney transplant. Design: This study was a retrospective analysis of the Organ Procurement and Transplant Network/United Network for Organ Sharing database. Subjects: The study sample consisted of 30,132 morbidly obese (body mass index [BMI] 35-40 kg/m2) and normal-weight (BMI 18.524.9 kg/m2) patients who underwent primary kidney-only transplantation between 2001 and 2006. Main Outcome Measure: Crude 3-year graft and patient survival rates of morbidly obese and normal-weight subgroups were evaluated. Logistic regression modeling compared 3-year graft failure and patient mortality in morbidly obese and normal-weight subgroups with opposite characteristics. Kaplan-Meier survival curves were created for 3-year graft and patient survival. Cox proportional hazard regression modeling was used to determine hazards for patient and graft mortality. Results: No differences in crude graft and patient survival rates were seen between normal weight and morbidly obese recipients who were African American, diabetic, and 50 to 80 years of age. Morbidly obese recipients who were nondialysis dependent, nondiabetic, had good functional status, and received living-donor transplants had significantly lower 3-year graft failure and patient mortality risk compared with normal-weight recipients who were dialysis dependent, diabetic, had poor functional status, and received a deceased-donor transplant, respectively (P , .01). Morbidly obese recipients have significantly lower graft and patient survival curves compared with normal-weight recipients; however, multivariate regression analysis reveals that morbid obesity is not an independent predictor of graft failure or patient mortality. Conclusions: Morbid obesity is not independently associated with graft failure or patient mortality; therefore, it should not be used as a contraindication to kidney transplantation. Ó 2014 by the National Kidney Foundation, Inc. All rights reserved.

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Introduction

IDNEY TRANSPLANTATION IS superior to long-term dialysis by improving quality of life and increasing survival among patients with end-stage renal disease.1 This benefit is also seen for obese recipients of deceased- and living-donor kidneys.2 However, 99% of all centers set absolute weight limits for transplant, with most using body mass index (BMI) greater than 35 kg/ *

The Transplant Center, Robert Wood Johnson University Hospital, New Brunswick, New Jersey † Department of Surgery, Robert Wood Johnson Medical School, New Brunswick, New Jersey ‡ Department of Medicine, Robert Wood Johnson Medical School, New Brunswick, New Jersey Financial Disclosure: The authors declare that they have no relevant financial interests. Address correspondence to Daniel Pieloch, MS, RD, Robert Wood Johnson University Hospital, The Transplant Center, 10 Plum Street, 7th Floor, New Brunswick, NJ 08901. E-mail: [email protected] Ó 2014 by the National Kidney Foundation, Inc. All rights reserved. 1051-2276/$36.00 http://dx.doi.org/10.1053/j.jrn.2013.07.001

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m2 as the criteria for noneligibility.3,4 This practice is prevalent because obesity is widely believed to be associated with greater patient and graft mortality, and centers are largely judged on these outcomes.5,6 Analysis of national databases show that obesity is associated with decreased patient and graft survival after kidney transplant.7,8 However, numerous studies from individual centers report no difference in outcome for their obese recipients.9-18 No universal guidelines exist for determining acceptable transplant candidates, with each center developing its own selection criteria.4 Centers weigh predictors of poor outcomes differently, and this may explain why some centers report better outcomes with their obese recipients. Characteristics such as advanced age,19 African-American race,20,21 poor functional status,22-24 diabetes,25 dialysis dependency,26 and deceased donor type27 are all known predictors of survival in transplant recipients; however, unlike obesity, they are rarely used as absolute contraindications. It is unclear why this bias exists, but an internal analysis at our center suggests that morbid obesity affects outcomes

Journal of Renal Nutrition, Vol 24, No 1 (January), 2014: pp 50-57

MORBID OBESITY AND KIDNEY TRANSPLANT OUTCOME

differently in various kidney transplant populations and that some subgroups of morbidly obese recipients have better graft and patient survival than many normal-weight recipients. To further investigate how graft failure and patient mortality rates compare in different populations of morbidly obese and normal-weight recipients, we performed a retrospective analysis of adult kidney transplant recipients from the Organ Procurement and Transplant Network (OPTN)/United Network for Organ Sharing (UNOS) database.

Methods Data for this study were derived from the UNOS/ Standard Transplant Analysis and Research files from 2001 to 2006. The study population consisted of all adult patients who underwent kidney transplantation from living and deceased donors. Patients with previous kidney transplantation and multiorgan transplantation were excluded. On the basis of height at registration and weight at transplantation, we calculated BMI for each patient. Following the National Institutes of Health guidelines, we selected two groups for this analysis: patients with normal weight (BMI 18.5-24.9 kg/m2) and those with morbid obesity (BMI 35-40 kg/m2). Sixteen different patient subgroups were identified and used to compare outcomes in morbidly obese and normal-weight recipients. Subgroups were selected based on common characteristics known to affect outcomes in kidney transplantation, including age, race/ethnicity, functional status, dialysis dependency, diabetes, and donor type. Age was subdivided into four groups (18-34 years, 35-49 years, 50-64 years, and 65-80 years), and race/ethnicity was divided into white, African American, Hispanic, and other. For functional status, most patients in the UNOS/ Standard Transplant Analysis and Research file before 2005 were characterized as no assistance, some assistance, or total assistance. Newer criteria based on percentages are seen after this date and were like-matched to one of the previous categories. Our primary outcomes were 3year graft failure and patient mortality. Graft failure was defined as a permanent return to dialysis or death with functioning graft. Patient subgroups were further analyzed with logistic regression modeling comparing 3-year graft failure and patient mortality in those who were morbidly obese with characteristics associated with positive outcomes to their normal-weight counterparts with the opposite characteristic. Morbidly obese recipients who were younger (18-34 years), nondiabetic, white, nondialysis dependent, needed no assistance with functional status, and those that received living-donor kidney transplants were compared with normal-weight recipients who were older (65-80 years), diabetic, African American, dialysis dependent, needed assistance with functional status, and received a deceased-donor kidney transplants, respectively.

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Statistical Analysis All statistical analyses were performed using the SAS software, version 9.2 (SAS Institute, Cary, NC), and a value of P , .05 was considered statistically significant. Patients’ 3-year crude survival rate in each study group was calculated by dividing the number of persons in the group who were still alive at 3 years after transplantation by the total number of persons in this group and expressed as a percentage. Likewise, 3-year crude graft failure rate was calculated by dividing the number of patients who permanently returned to dialysis or died with functioning graft at 3 years after transplantation by the total number of patients. To evaluate the difference between two groups, we used the c2 analysis for categorical variables and the Student’s t test for continuous variables. Logistic regression models were used to compare 3-year graft failure and patient mortality among the subgroups, each controlling for a different combination of the following factors: age, gender, race/ethnicity, functional status, dialysis dependency, diabetes, peripheral vascular disease (PVD), donor type, cold ischemia time, and the level of human leukocyte antigen (HLA) matching. Kaplan-Meier survival curves were used demonstrate 3year graft and patient survival. Cox proportional hazards regression models were created to determine hazards for 3-year graft failure and patient mortality, controlling for age, gender, race/ethnicity, functional status, dialysis dependency, diabetes, PVD, donor type, cold ischemia time, and the level of HLA matching. The study protocol was approved by the Institutional Review Board at the University of Medicine and Dentistry of New Jersey.

Results Those kidney transplant recipients who met the inclusion/exclusion criteria (n 5 30,132) were included in this study. Baseline characteristics for the study population are shown in Table 1. Morbidly obese recipients compared with normal-weight patients were older (50-80 years of age; P ,.001), more likely to require assistance for daily living (P ,.001), had a higher incidence of diabetes (P ,.001) and PVD (P , .001), were more often dialysis dependent (P 5 .002), and were more likely to receive a deceaseddonor kidney transplant (P , .001). Table 2 displays crude graft and patient 3-year survival rates in normal-weight and morbidly obese recipient subgroups. In most subgroups, graft survival was significantly lower in morbidly obese recipients compared with normal-weight recipients (P , .02). Patient survival was only significantly lower in morbidly obese recipients who were younger, Hispanic, dialysis dependent, needed no assistance in functional status, and received a living-donor transplant. Morbidly obese African Americans, diabetics, and those older than 50 years of age had similar graft and patient survival rates compared with those with of normal weight.

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Table 1. Characteristics of Study Sample Characteristics Number of recipients Age (mean 6 SD)* Age groups, n (%)* 18-34 y† 35-49 y† 50-64 y† 65-80 y† Gender, n (%) Male† Female† Race, n (%) White African American† Hispanic† Other† Functional status, n (%)* No assistance† Some assistance† Total assistance Comorbidity, n (%) Diabetes mellitus† PVD† Dialysis, n (%) Dependent† HLA mismatch, n (%) 0 mismatch Donor type, n (%) Deceased†

BMI 18.5-24.9 kg/m2

BMI 35-40 kg/m2

24,077 47.0 6 14.3

6,055 49.9 6 11.9

5,409 (22.5) 7,610 (31.6) 8,101 (33.7) 2,930 (12.2)

725 (12.0) 2,010 (33.2) 2,690 (44.4) 628 (10.4)

13,737 (57.1) 10,340 (42.9)

3,350 (55.3) 2,705 (44.7)

13,423 (55.8) 5,065 (21.0) 3,275 (13.6) 2,314 (9.6)

3,414 (56.4) 1,722 (28.4) 671 (11.1) 248 (4.1)

19,559 (87.6) 2,647 (11.9) 117 (0.5)

4,686 (83.8) 887 (15.9) 22 (0.4)

5,283 (22.0) 651 (2.9)

2,499 (41.3) 267 (4.7)

19,720 (82.0)

5,061 (83.6)

2,685 (11.2)

643 (10.7)

13,597 (56.5)

3,645 (60.2)

BMI, body mass index; HLA, human leukocyte antigen; PVD, peripheral vascular disease. *Some values in this category are missed. †P , .05.

Figure 1 displays logistic regression analysis that compares 3-year graft failure in morbidly obese subgroups that were younger, white, had good functional status, were nondiabetic, were nondialysis dependent, and those who received living-donor kidney transplants and compared them with normal-weight recipients that were older, African American, had poor functional status, were diabetic, were dialysis dependent, and those who received a deceased-donor kidney transplant, respectively. Morbidly obese subgroups that were nondialysis dependent (odds ratio [OR], 0.69; 95% confidence interval [CI], 0.54-0.87; P 5 .001), nondiabetic (OR, 0.86; 95% CI, 0.76-0.98; P , .001), white (OR, 0.83; 95% CI, 0.730.95; P 5 .007), received living-donor transplants (OR, 0.78; 95% CI, 0.66-0.89; P , .001), and needed no assistance with daily activities (OR, 0.80; 95% CI, 0.70-0.91; P 5 .001) had significantly lower 3-year graft failure when compared with normal-weight subgroups who were dialysis dependent, diabetic, African American, received deceased-donor transplants, and had functional status requiring assistance, respectively. There was no significant difference in 3-year graft failure between morbidly obese recipients aged 18 to 34 years (OR, 0.90; 95% CI, 0.70-1.16; P 5 .412) and normal-weight recipients aged 65 to 80 years. Logistic regression analysis comparing 3-year patient mortality in the same morbidly obese and normal-weight subgroups is displayed in Figure 2. Morbidly obese subgroups that were nondialysis dependent (OR, 0.44; 95% CI, 0.300.63; P , .001), nondiabetic (OR, 0.53; 95% CI, 0.440.63; P , .001), younger (OR, 0.24; 95% CI, 0.16-0.38;

Table 2. Crude Graft and Patient Survival Rates in Normal-Weight and Morbidly Obese Recipient Subgroups 3-y Graft Survival (%) Subgroups Age group 18-34 y 35-49 y 50-64 y 65-80 y Race/ethnicity White African American Hispanic Functional status No assistance Some assistance Total assistance Diabetes Nondiabetic Diabetic Dialysis dependency Nondialysis Dialysis Donor type Living donor Deceased donor

3-y Patient Survival (%)

Normal Weight

Morbidly Obese

P

Normal Weight

Morbidly Obese

P

87.76 88.28 83.77 78.12

83.59 83.23 83.46 76.91

.002 ,.001 .706 .507

97.80 95.72 89.47 82.56

96.69 94.18 90.00 83.44

.063 .004 .435 .597

86.58 78.74 88.70

83.92 78.46 85.10

,.00 .80 .009

92.16 90.90 94.78

91.33 91.06 92.40

.109 .843 .015

86.28 80.09 70.94

83.65 77.23 63.64

,.001 .068 .494

93.19 88.02 83.76

92.36 86.70 77.27

.044 .298 .822

86.47 81.70

84.09 80.75

,.001 .318

94.00 86.96

94.01 87.92

.985 .237

91.92 84.00

89.45 81.33

.014 ,.001

96.07 91.71

95.52 90.67

.444 .019

90.32 81.58

86.76 80.00

,.001 .030

95.61 90.03

93.94 89.85

,.001 .751

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Figure 1. Comparing 3-year graft failure of morbidly obese versus normal-weight kidney transplant recipients with opposite characteristics using logistic regression analysis. *Adjusted for age, race, functional status, donor type, HLA mismatch, and diabetes. †Adjusted for age, race, dialysis dependency, functional status, HLA mismatch, cold ischemic time, PVD, and diabetes. ‡Adjusted for age, race, functional status, dialysis dependency, donor type, and HLA mismatch. §Adjusted for age, functional status, donor type, HLA mismatch, cold ischemic time, and PVD. kAdjusted for age, race, dialysis dependency, donor type, HLA mismatch, cold ischemic time, PVD, and diabetes. {Adjusted for race, functional status, dialysis dependency, donor type, HLA mismatch, cold ischemic time, PVD, and diabetes. Normal weight 5 body mass index 18.5-24.9 kg/m2. Morbidly obese 5 body mass index 35-40 kg/m2. HLA, human leukocyte antigen; PVD, peripheral vascular disease.

P ,.001), received living-donor transplant (OR, 0.59; 95% CI, 0.48-0.72; P ,.001), and needed no assistance with daily activities (OR, 0.61; 95% CI, 0.51-0.72; P ,.001) had significantly lower 3-year patient mortality compared with normal weight subgroups who were dialysis dependent, diabetic, older, received deceased-donor transplants, and had functional status requiring assistance, respectively. A trend was seen for improved 3-year patient mortality between white morbidly obese recipients aged 18 to 34 years (OR, 0.90; 95% CI, 0.70-1.16; P 5 .412) and normal-weight AfricanAmerican recipients. Figures 3 and 4 display Kaplan-Meier curves for graft and patient survival during the first 3 years after kidney trans-

plantation in normal-weight and morbidly obese kidney transplant recipients. Morbidly obese recipients have significantly lower graft and patient survival compared with normal-weight recipients (P , .002). Figures 5 and 6 display the results of the Cox proportional hazards regression modeling and demonstrate hazard ratios (HRs) for 3-year graft failure and patient mortality, controlling for morbid obesity, age, gender, race, functional status, diabetes, PVD, dialysis dependency, the level of HLA matching, cold ischemia time, and donor type. As shown in these figures, morbid obesity did not significantly affect graft failure (HR, 1.04; 95% CI, 0.98-1.11; P 5.209) or patient mortality (HR, 1.03; 95% CI, 0.96-1.12; P 5 .360). Figure 2. Comparing 3-year patient of morbidly of morbidly obese versus normalweight kidney transplant recipients with opposite characteristics using logistic regression analysis. *Adjusted for age, race, functional status, donor type, HLA mismatch, PVD, and diabetes. †Adjusted for age, race, functional status, dialysis dependency, HLA mismatch, cold ischemic time, PVD, and diabetes. ‡Adjusted for age, race, functional status, dialysis dependency, donor type, and PVD. §Adjusted for age, functional status, donor type, dialysis dependency, HLA mismatch, PVD, and diabetes. kAdjusted for age, dialysis dependency, donor type, PVD, and diabetes. {Adjusted for race, functional status, dialysis dependency, donor type, HLA mismatch, PVD, and diabetes. Normal weight 5 body mass index 18.5-24.9 kg/m2. Morbidly obese 5 body mass index 35-40 kg/m2. HLA, human leukocyte antigen; PVD, peripheral vascular disease.

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Figure 3. Three-year graft survival of normal weight and morbidly obese kidney transplant recipients.

Predictors of graft failure and patient mortality were diabetes, cold ischemia time greater than 24 hours, any HLA mismatch, deceased-donor type, dialysis dependency, poor functional status requiring some and total assistance with daily activities, African-American race, male gender, and age over 65 years (P , .025).

Discussion Although our study of 30,132 kidney transplant recipients with 3-year follow-up showed that morbidly obese recipients have lower graft and patient survival curves than normal-weight recipients, some morbidly obese subgroups demonstrated lower risk of graft failure and patient mortality than many normal-weight recipients when adjusting for other risk factors. Also, morbid obesity was not an independent predictor of higher graft failure or patient mortality rates. Because obesity is widely used as an absolute contraindication for kidney transplant, these findings may have major clinical impact, particularly in providing greater access to transplant for those who are obese. Although numerous studies have looked at outcomes of obese transplant recipients, subgroup analysis of this population has been largely unexplored. To the best of our knowledge, of the characteristics we identified, only donor type and age have been previously studied in obese recipi-

Figure 4. Three-year patient survival of normal-weight and morbidly obese kidney transplant recipients.

ents with respect to graft and patient survival. Using U.S. Renal Data System data from 1995 to 1999, Glanton and colleagues showed lower survival rates in deceased- and living-donor recipients who are obese compared with deceased- and living-donor recipients with normal weight.2 However, obese living-donor recipients had better survival rates than nonobese deceased-donor recipients: 1.9 deaths/ 100 patient years compared with 2.8 deaths per 100 patient years, respectively.2 Our findings were similar except for morbidly obese recipients of deceased-donor recipients, in which we saw no difference in mortality compared with similar recipients with normal weight. Hatamizadeh and colleagues studied transplanted recipients between 2001 and 2007 using the OPTN/UNOS database and showed that obesity (BMI . 30 kg/m2) was associated with a 19% higher risk of graft failure in those aged 65 to more than 70 years when graft failure was defined as reinitiation of dialysis or retransplantation; however, when conventional death censored graft survival analysis was performed, obesity was not associated with graft failure in this same age group.28 Obesity was an independent predictor of all-cause mortality in those older than 75 years of age but not for those aged between 65 and 75 years.28 Although in our study morbid obesity was shown not to affect outcome in African Americans, diabetics, and those aged 50 years and older, it is unclear why, particularly for graft survival, there is a strong association in many of the other subgroups. Being African American, diabetic and elderly are all associated with worse outcomes after transplantation and may just overshadow the effect of being morbidly obese. Our findings may help explain the disparity of why morbidly obese transplant recipients display worse graft and patient survival in large analyses but multiple individual centers report no difference in outcome.9-18 Centers that transplant higher rates of morbidly obese subgroups that are younger, nondiabetic, nondialysis dependent, white, have good functional status, and who receive livingdonor transplants may show above-average positive results for this population. For example, in our study, these subgroups had better graft and patient survival than normalweight deceased donor recipients, who account for over 50% of all normal-weight transplants performed. These centers may have also transplanted less morbidly obese subgroups that portend poor outcomes. It is difficult to make direct comparisons to these studies because most of them incompletely characterize their morbidly obese population and often do not provide their guidelines for recipient eligibility. It is unclear if these subgroups of morbidly obese recipients would also display better rates of postoperative wound and graft complications such as infection, delayed graft function, and rejection, which are more often seen in obese transplant recipients.8

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Figure 5. Hazard ratios: 3-year graft failure. BMI, body mass index; HLA, human leukocyte antigen.

Another important finding from our study is that morbid obesity is not independently associated with increased graft failure or patient mortality. Similar to our findings, a 2011 study by Streja and colleagues demonstrated that morbid obesity did not influence patient survival after 6 years; however, a nonsignificant trend was seen toward higher graft loss in 10,090 maintenance dialysis patients who underwent kidney transplantation.29 In contrast, an analysis of the U.S. Renal Data System demonstrated that morbid obesity is a strong independent risk factor for patient mortality and graft failure in 51,927 dialysis patients who underwent kidney transplant from 1988 to 1997.8 Differences in immunosuppressive protocols may make comparisons to our study difficult. These studies involve recipients from national dialysis registries, and although dialysis patients make up most Figure 6. Hazard ratios: 3-year patient failure. BMI, body mass index; HLA, human leukocyte antigen.

of those who undergo kidney transplantation, 14.4% of kidney transplants are preemptive.30 Gore and colleagues identified 27,377 kidney transplant recipients with follow-up through 2004 from the OPTN/ UNOS database and demonstrated that morbid obesity was an independent risk factor for graft failure and was associated with a 22% increased risk of graft loss compared with normal-weight recipients after 5 years.8 Of note, we classified morbid obesity as a BMI of 35 to 40 kg/m2 whereas Gore and colleagues included in their analysis the most extreme of morbidly obese recipients (BMI . 40 kg/m2). Unlike morbid obesity, factors such as donor type, age, race, functional status, dialysis dependency, and diabetes are rarely used as absolute contraindications to transplant,

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but our findings suggest that these characteristics serve as better predictors of graft failure and patient mortality. Gore and colleagues’ multivariate analysis for graft failure risk shows similar findings for donor type and race, but no significant difference in risk between morbid obesity and diabetes.8 It is unclear why such strong emphasis is placed on obesity for kidney transplant eligibility whereas other factors that predict poor outcomes are not emphasized. One may argue it is due to obesity being a modifiable risk factor; however, other modifiable risk factors such as smoking and lack of exercise rarely preclude patients from kidney transplant. Although never studied in the transplant community, the stigma of obesity may play a role in this bias.31 Health-care professionals frequently report negative attitudes about obesity, which is thought to affect patient care.32-35 Segev and colleagues showed that morbidly obese patients are 28% to 44% less likely to receive a kidney transplant, even after adjusting for comorbidities that might affect eligibility.36 Likewise, morbidly obese recipients had a 4% to 23% higher likelihood of being bypassed when an organ became available compared with normal-weight recipients.36 Some centers may avoid transplanting obese recipients because of added expense and increased resource utilization as a result of anticipated surgical complications, including increased wound and surgical site infections, higher nerve injury rates, and urinary tract infections.37,38 Centers may also primarily avoid transplanting morbidly obese recipients because of their higher rates of delayed graft function, increased length of stay, and higher incidence of acute rejection and early graft loss.8 It is also recognized that BMI is an imperfect tool to measure obesity. Some patients may have a normal BMI in the setting of high fat mass and low muscle mass, whereas others with a BMI greater than 35 kg/m2 may have high muscle mass but minimal fat mass. Measures of fat distribution such as waist circumference and degree of lean body mass, measured by serum creatinine, have been proven to be better predictors of patient and graft survival than BMI alone in kidney transplant recipients.29,39 Our study has several limitations, some common to all retrospective database analysis, including selection bias, misclassification errors, and/or missing values. Cardiovascular disease was not included in our multivariate analysis because it was difficult for us to extract from the OPTN/ UNOS database. Subgroup analysis was performed for our morbidly obese and normal-weight subgroups, but it was not adjusted for other factors such as demographic or comorbid conditions. However, a large sample size was a strong point of the study. We looked only at morbidly obese recipients with a BMI between 35 and 40 kg/m2. We considered recipients with a BMI greater than 40 kg/m2 extreme cases; therefore, they were not included in our analysis. It can be argued that morbidly obese pa-

tients who receive kidney transplants are likely selected for better than average health or undergo transplant at specialized centers. To help account for this, we chose the time frame before the 2007 Centers for Medicare and Medicaid Services rule changes that led to an increase in oversight of transplant programs. Morbid obesity was less commonly used as a contraindication to kidney transplantation before these rule changes. It is also important to note that our findings may not apply to less obese recipients in the group with the BMI range of 30 to 34.9 kg/m2 that was not studied.

Conclusion Morbid obesity does not independently predict higher rates of graft failure or patient mortality at 3 years after kidney transplant and may not influence graft and patient survival in certain subsets of morbidly obese subgroups, including African Americans, diabetics, and older recipients. Morbidly obese recipients who are nondiabetic, nondialysis dependent, have good functional status, and receive living-donor transplants have lower risk of 3-year graft failure and patient mortality than many normal-weight recipients. On the basis of these results, the practice of denying patients access to transplant because of morbid obesity alone should be abandoned, particularly in those subgroups that demonstrated better outcomes compared with normal-weight recipients.

Practical Application Morbid obesity is often used as an absolute contraindication to kidney transplantation. However, other risk factors that are associated with higher rates of graft failure and patient mortality compared with morbid obesity are rarely used as absolute contraindications, such as being diabetic, dialysis dependent, or elderly. In general, obesity should be treated as one of multiple risk factors in determining transplant candidacy.

References 1. 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;341:1725-1730. 2. Glanton CW, Kao TC, Cruess D, et al. Impact of renal transplantation on survival in end-stage renal disease patients with elevated body mass index. Kidney Int. 2003;63:647-653. 3. Pondrom S. The AJT Report: News and issues that affect organ and tissue transplantation. Am J Transplant. 2012;12:1663-1664. 4. Kramer HJ, Saranathan A, Luke A, et al. Increasing body mass index in the incident ESRD population. J Am Soc Nephrol. 2006;17:1453-1459. 5. Johnson KL. Obesity and body composition for transplant wait-list candidacy-challenging or maintaining the BMI limits? J Ren Nutr. 2013;23:207. 6. Srinivas TR, Meier-Kriesche HU. Obesity and kidney transplantation. Semin Nephrol. 2013;33:34-44. 7. Potluri K, Hou S. Obesity in kidney transplant recipients and candidates. Am J Kidney Dis. 2010;56:143-156. 8. Gore JL, Pham PT, Danovitch GM, et al. Obesity and outcome following renal transplantation. Am J Transplant. 2006;6:357-363.

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