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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2014  |  Volume : 25  |  Issue : 2  |  Page : 303-308
Obesity and urologic complications after renal transplantation

1 Research Center, Department of Internal Medicine, Iran University of Medical Sciences, Tehran, Iran
2 Department of Urology, Hasheminejad Hospital, Iran University of Medical Sciences, Tehran, Iran
3 Division of Nephrology, Department of Internal Medicine, Saint Louis University School of Medicine, Saint Louis, USA

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Date of Web Publication11-Mar-2014


Although obesity has been associated with improved survival on dialysis, its short-and long-term effects on renal transplantation outcomes remain unclear. Herein, we evaluate the short-term and intermediate long-term effects of obesity on first-time renal transplant patients. A retrospective analysis was performed on 180 consecutive renal transplant recipients from living unrelated donors during 2006-2008 in a major transplantation center in Tehran, Iran. Among these, 34 (18%) patients were found to be obese (body mass index ≥30 kg/m 2 ). Obese patients were more likely to develop post-transplant renal artery stenosis (RAS) (17.6% vs. 2.8%, P <0.001), hematoma (47.9% vs. 17.6, P = 0.009), surgical wound complications (64.7% vs. 9.6%, P <0.001) and renal vein thrombosis (2% vs. 0%, P <0.001). However, the incidence of delayed graft function, lymphocele, urologic complications of ureterovesical junction stenosis or urinary leakage, surgical complications of excessive bleeding or renal artery thrombosis and duration of hospitalization were similar between the two groups. The two-year patient and graft survival were also statistically not different. Renal transplantation in obese recipients is associated with a higher incidence of post-transplant RAS, hematoma, surgical wound complications and renal vein thrombosis, but similar two-year patient and graft survival.

How to cite this article:
Behzadi AH, Kamali K, Zargar M, Abbasi MA, Piran P, Bastani B. Obesity and urologic complications after renal transplantation. Saudi J Kidney Dis Transpl 2014;25:303-8

How to cite this URL:
Behzadi AH, Kamali K, Zargar M, Abbasi MA, Piran P, Bastani B. Obesity and urologic complications after renal transplantation. Saudi J Kidney Dis Transpl [serial online] 2014 [cited 2020 Jun 4];25:303-8. Available from: http://www.sjkdt.org/text.asp?2014/25/2/303/128516

   Introduction Top

Obesity is considered a nutritional epidemic; 65% of the adult population in the US in 2002 were overweight [body mass index (BMI) = 25-29.9 kg/m 2 ]or obese (BMI ≥30 kg/m²), of which 30.4% were obese and 4.9% were extremely obese (BMI ≥40 kg/m²). [1] The prevalence of obesity in patients with end-stage renal disease (ESRD) has also increased rapidly. [2],[3] In 2001, 60% of the renal transplant candidates in the United States were either obese or overweight, and between 1987 and 2001, the proportion of obese renal transplant recipients had increased by 116%. [4] Kidney transplantation not only improves the quality of life but also significantly improves patients' survival as compared with the dialysis patients who remain on the waiting list. This survival advantage has been apparent for recipients of live and deceased (ideal or marginal kidneys) donors as well as in the obese recipients. [5],[6] Although obesity has been associated with improved survival on dialysis, its effects on renal transplant outcomes remain unclear. Some authors have reported an inferior outcome for obese kidney transplant recipients, [7],[8],[9],[10],[11],[12] whereas others report no difference in outcomes. [13],[14],[15],[16],[17] This may be related in part to the selection of the study populations, as most reports do not differentiate between obese patients (BMI between 30 and 35 kg/m²) and morbidly obese patients (BMI 35 kg/m²). The aim of this study was to compare surgical complications and intermediate-term patients and graft survival rates after renal transplantation among obese and non-obese recipients of living unrelated donors.

   Patients and Methods Top

We retrospectively reviewed the charts of all patients over 15 years of age who had undergone living unrelated donor kidney transplantation between April 2006 and January 2008 at Hasheminejad Hospital, Tehran, Iran. Exclusion criteria were multi-organ transplantation or a history of prior renal transplantation and recipient age <15 years. A total of 180 patients were included in the study. End-to-end arterial anastomosis was performed between renal transplant artery and internal iliac artery. The transplant renal vein was anastomosed to the external iliac vein with an end-to-side anastomosis. The ureter was anastomosed with the anterior Lich technique and ureter stent was placed in all patients, which were removed after two weeks. A triple immunosuppressive protocol therapy including cyclosporin, mycophenolate mofetil and prednisolone was administered for all recipients.

The patients had a minimum of two years of follow-up. Information regarding recipient age and sex, donor age and sex, vascular complications, lymphocele, hemorrhage, urinary leakage and ureteral stenosis, wound complications (infection and dehiscence), delayed graft function (DGF), defined as the need for dialysis in the first week after renal transplantation) and BMI at the time of transplantation was retrieved from the renal transplant database.

   Statistical Analysis Top

Data are shown as means ± SD. Graft survival was evaluated by the Kaplan-Meier method. Univariate comparison between Kaplan- Meier curves of the two groups was evaluated by Breslow statistics and log rank analysis. The statistical significance of differences was determined by chi-square analysis with Yates correction. Statistical significance was defined as P <0.05.

   Results Top

During the two-year period between April 2006 and January 2008, 180 patients underwent transplantation, 34 (18%) were obese (BMI ≥30 kg/m²) and 146 (82%) were non-obese (BMI <30 kg/m 2 ). There were no morbidly obese (BMI >35 kg/m²) patients in this retrospective cohort. There were 70 (39%) women and 110 (61%) men. The mean age of the recipients and donors was 39.8 ± 14.9 (range, 15-77) and 29.3 ± 6.2 (range, 21-34) years, respectively. Some demographic characteristics of obese and non-obese patients are shown in [Table 1]. There were no major differences between the two groups with regard to gender, age and prevalence of hypertension or diabetes.
Table 1: Baseline characteristics of obese (BMI >30kg/ m2) and non-obese renal transplant recipients.

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Obese patients were more likely to develop renal artery stenosis (RAS) (17.6% vs. 2.8%, P <0.001), hematoma (47.9% vs. 17.6%, P = 0.009), surgical wound complications (64.7% vs. 9.6%, P <0.001) and renal vein thrombosis (2% vs. 0%, P <0.05) as compared with non-obese recipients [Table 2]. There were no significant differences between the two groups with respect to delyed graft function (DGF), lymphocele, uretero-pelvic obstruction, uretero-vesical junction(UVJ) obstruction, surgical wound bleeding, urinary leakage, renal artery thrombosis and duration of hospitalization [Table 2]. A total of ten patients had developed transplant RAS, six in the obese and four in the non-obese group. Of the six patients in the obese group, two were treated medically, two had undergone percutaneous angioplasty and two had undergone surgical endarterectomy. Of the four patients in the non-obese group, two were treated medically, one had undergone percutaneous angioplasty and one had undergone surgical endarterectomy. The two-year graft survival rate in the obese patients was similar to the non-obese recipients (94.1% vs. 96.7%, P = 0.42, respectively). The two-year patient survival rate was 100% in both groups.
Table 2: Univariate analysis of recipient BMI and post-operative graft complications.

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   Discussion Top

During the last two decades, the prevalence of obese patients undergoing renal transplantation has more than doubled and, currently, about 60% of patients on the waiting list for a transplant are either overweight or obese. [4]

The impact of recipient obesity on patient and graft survival is controversial. Some reports describe B MI as a putative independent risk factor for patient mortality and death-censored graft failure rate after renal transplantation. [18] However, others have found no association between obesity and adverse graft survival, despite the increased risk among obese recipients for wound infections and DGF. [13],[14],[15],[16],[17] In a recent analysis of the UNOS data base of 27,377 kidney-only transplantations between 1997 and 1999, morbid obesity (BMI 35 kg/ m 2 ) was independently associated with an increased risk of DGF, prolonged hospitalization, acute rejection and decreased overall graft survival. [19] Moreover, a recent report on 11,836 hemodialysis patients in the Scientific Registry of Transplant Recipients (SRTR) showed that pre-transplant overweight, obesity and morbid obesity were associated with incrementally higher risk of DGF. [20] However, registry studies suggest that patients with high BMI receive a benefit from transplantation on mortality [6] and cardiovascular complications as compared with those remaining on the waiting list. [21],[22] Moreover, a recent report from the Netherlands shows that the one-year post-transplant BMI and BMI change were more strongly associated with death and graft failure than pre-transplantation BMI. [23] They found that BMI >30 kg/m² had a 20-40% higher risk of death-censored graft failure rate at one year. [23]

We observed a significantly higher incidence of post-transplant vascular complications, such as RAS, renal vein thrombosis and hematoma and surgical wound complications in our obese renal transplant recipients as compared with the non-obese recipients. However, obesity was not associated with short-term or intermediate- long-term post-transplant complications such as DGF, lymphocele, ureter, ureteropelvic or UVJ obstruction, ureteric dehiscence/urine leakage, excessive surgical site bleeding, renal artery thrombosis or increase in hospitalization time. We also found similar two-year patient and graft survival between the obese and non-obese recipients. Similar to our findings, Singh et al detected no association between obesity and major short-term or long-term post-transplant complications; however, obese patients had significantly longer operating time, more wound infections, lymphocele, perinephric hematomas and longer hospitalization after transplantation. [24]

Our results are in accordance with the report by Johnson et al, who showed that obese patients were more likely to develop surgical wound complications, but no significant difference with respect to duration of surgery, post-operation complications, DGF, length of hospitalization or acute rejection rate. [13] More­over, their five-year patient and graft survival rates were similar between the obese and non-obese recipients. [13] Similar to our results, Merion et al [15] found a greater incidence of surgical wound complication, in the form of wound infection, in obese recipients while other parameters including three-year patient and graft survival rates were the same. Drafts et al have also reported similar results of increased incidence of wound infection and DGF, but no discernible impact on transplant outcome. [16] On the other hand, some authors have shown an association between obesity and post-transplant complications, including graft failure and patient death, [18] or urological complication and DGF. [25] This disparity might have been caused by improvement in patient management and transplant outcomes over the time.

In the present study we did not have recipients with morbid obesity (BMI >35 kg/m 2 ). According to Marks et al, kidney transplantation can be safely performed in morbidly obese patients with three-year patient and graft survivals similar to non-obese recipients, but with significantly longer hospital stays, higher readmission rates and higher wound infection rates. [26] Moreover, in an elegant study by Streja et al, there were no statistically significant differences in the adjusted risk for graft loss or post-transplant patient mortality in patients with BMI >25; however the three-month average pre-transplant serum creatinine <4 mg/dL was associated with a 2.2-fold higher risk of combined death or graft failure, whereas creatinine >14 mg/dL exhibited 22% better graft and patient survival. [27] Thus, while pre-transplant obesity did not appear to be associated with poor post-transplant outcome, larger pre-transplant muscle mass, as reflected by higher pre-transplant serum creatinine, was associated with better post-transplant graft and patient survival. [27] Finally, Kovesdy et al have recently reported that higher BMI was associated with lower mortality after adjustment for waist circumference, and that higher waist circumference was more strongly associated with higher mortality after adjustment for BMI; thus, waist circumference appears to be a better marker for obesity than BMI. [28]

The high incidence of transplant RAS in our obese group could be due to recipient vessel atheromatosis, which has been shown to be an important risk factor for both vascular thrombosis and transplant RAS. [29] Because of the retrospective nature of our study, we cannot substantiate on this possibility.

Obesity should not be considered as a contraindication for renal transplantation. Renal transplantation can be performed with acceptable urologic complications in obese patients with similar patient and graft survival as compared with non-obese patients.

Conflict of interest: None

   References Top

1.Hedley AA, Ogden CL, Johnson CL, Carroll MD, Curtin LR, Flrgal KM. Prevalence of overweight and obesity among U.S. children, adolescents, and adults, 1999-2002. JAMA 2004;291:2847-50.  Back to cited text no. 1
2.Aalten J, Christiaans MH, de Fijter H, et al. The influence of obesity on short- and long-term graft and patient survival after renal transplantation. Transpl Int 2006;19:901-7.  Back to cited text no. 2
3.Kramer HJ, Saranathan A, Luke A, et al. Increasing body mass index and obesity in the incident ESRD population. J Am Soc Nephrol 2006;17:1453-9.  Back to cited text no. 3
4.Friedman AN, Miskulin DC, Rosenberg IH, Levey AS. Demographics and trends in overweight and obesity in patients at the time of kidney transplantation. Am J Kidney Dis 2003; 41:480-7.  Back to cited text no. 4
5.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;12:589-97.  Back to cited text no. 5
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;63:647-53.  Back to cited text no. 6
7.Modlin CS, Flechner SM, Goormastic M, et al. Should obese patients lose weight before receiving a kidney transplant? Transplantation 1997;64:599-604.  Back to cited text no. 7
8.Meier-Kriesche HU, Vaghela M, Thambuganipalle R, Friedman G, Jacobs M, Kaplan B. The effect of body mass index on long-term renal allograft survival. Transplantation 1999;68:1294-7.  Back to cited text no. 8
9.Kasiske BL, Cangro CB, Hariharan S, et al. The evaluation of renal transplantation candidates: Clinical practice guidelines. Am J Transplant 2002;2:1-95.  Back to cited text no. 9
10.Johnson CP, Kuhn EM, Hariharan S, Hartz AJ, Roza AM, Adams MB. Pre-transplant identification of risk factors that adversely affect length of stay and charges for renal transplantation. Clin Transplantation 1999;13:168-75.  Back to cited text no. 10
11.Burdick RA, Leichtman AB, Bragg JL, et al. Obesity is associated with poorer outcomes in cadaveric renal transplant recipients (CRTx) but not in cadaveric liver transplant recipients (CLTx). Am Transplant Congress 2001, proceedings AST abstract 966.  Back to cited text no. 11
12.Yamamoto S, Hanley E, Hahn AB, et al. The impact of obesity in renal transplantation: An analysis of paired cadaver kidneys. Clin Transplant 2002;16:252-6.  Back to cited text no. 12
13.Johnson DW, Isbel NM, Brown AM, et al. The effect of obesity on renal transplant outcomes. Transplantation 2002;74:675-80.  Back to cited text no. 13
14.Howard RJ, Thai VB, Patton PR, et al. Obesity does not portend a bad outcome for kidney transplant recipients. Transplantation 2002;73: 53-5.  Back to cited text no. 14
15.Merion RM, Twork AM, Rosenberg L, et al. Obesity and renal transplantation. Surg Gynecol Obstet 1991;172:367-76.  Back to cited text no. 15
16.Drafts HH, Anjum MR, Wynn JJ, Mulloy LL, Bowley JN, Humphries AL. The impact of pre-transplant obesity on renal transplant outcomes. Clin Transplant 1997;11:493-6.  Back to cited text no. 16
17.Howard RJ, Thai VB, Patton PR, et al. Obese kidney transplant recipients have good outcomes. Transplant Proc 2001;33:3420-1.  Back to cited text no. 17
18.Meier-Kriesche HU, Arndorfer JA, Kaplan B. The impact of body mass index on renal transplant outcomes: A significant independent risk factor for graft failure and patient death. Transplantation 2002;73:70-4.  Back to cited text no. 18
19.Gore JL, Pham PT, Danovitch GM, et al. Obesity and outcome following transplantation. Am J Transplantation 2006;6:357-63.  Back to cited text no. 19
20.Molnar MZ, Kovesdy CP, Mucsi I, et al. Higher recipient body mass index is associated with post-transplant delayed kidney graft function. Kidney Int 2011;80:218-24.  Back to cited text no. 20
21.Lentine KL, Xiao H, Brennan DC, et al. The impact of kidney transplantation on heart failure risk varies with candidate body mass index. Am Heart J 2009;158:972-82.  Back to cited text no. 21
22.Meier-Kriesche HU, Schold JD, Srinivas TR, Reed A, Kaplan B. Kidney transplantation halts cardiovascular disease progression in patients with end-stage renal disease. Am J Transplant 2004;4:1662-8.  Back to cited text no. 22
23.Hoogeveen EK, Aalten J, Rothman KJ, et al. Effect of obesity on the outcome of kidney transplantation: A 20-year follow-up. Transplantation 2011;91:869-74.  Back to cited text no. 23
24.Singh D, Lawen J, Alkhudair W. Does Pre-transplant Obesity Affect the Outcome in Kidney Transplant Recipients? Transplant Proc 2005;37:717-20.  Back to cited text no. 24
25.Pirsch JD, Armbrust MJ, Knechtle SJ, et al. Obesity as a risk factor following renal transplantation. Transplantation 1995;59:631-3.  Back to cited text no. 25
26.Marks WH, Florence LS, Chapman PH, Precht AF, Perkinson DT. Morbid obesity is not a contraindication to kidney transplantation. Am J Surg 2004;187:635-8.  Back to cited text no. 26
27.Streja E, Molnar MZ, Kovesdy CP, et al. Associations of pretransplant weight and muscle mass with mortality in renal transplant recipients. Clin J Am Soc Nephrol 2011;6:1463-73.  Back to cited text no. 27
28.Kovesdy CP, Czira ME, Rudas A, et al. Body mass index, waist circumference and mortality in kidney transplant recipients. Am J Transplant 2010;10:2644-51.  Back to cited text no. 28
29.Galazka Z, Szmidt J, Nazarewski S, et al. Long term results of kidney transplantation in recipients with atherosclerotic iliac arteries. 2002;26:754-64.  Back to cited text no. 29

Correspondence Address:
Bahar Bastani
Division of Nephrology, Department of Internal Medicine, Saint Louis University School of Medicine, Saint Louis, MO
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DOI: 10.4103/1319-2442.128516

PMID: 24625995

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