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Effect of Pretransplantation Body Mass Index on Allograft Function and Patient Survival After Renal Transplantation
Effect of Pretransplantation Body Mass Index on Allograft Function and Patient Survival After Renal Transplantation M.M. Abou-Jaoude, N. Nawfal, R. Najm, M. Honeidi, J. Shaheen, and W.Y. Almawi ABSTRACT We evaluated the effects of pretransplantation recipient body mass index (BMI) on allograft survival and on kidney function. Kidney transplant recipients were grouped according to their pretransplantation BMIs: Group I (BMI ⬍18.5 kg/m2; n ⫽ 10); Group II (BMI 18.5–24.9 kg/m2; n ⫽ 62); Group III (BMI 25.0 –29.9 kg/m2; n ⫽ 47); and Group IV (BMI ⬎30.0 kg/m2; n ⫽ 16). Excellent 1-year patient and graft survival rates were observed in all groups. Increased BMI was associated with increased hypertension and longer hospital stays. The incidence of acute rejection episodes, slow graft function, and delayed graft function, as well as the need for antithymocyte globulin Fresenius (ATG-F) rescue therapy were comparable between the 4 patient groups. The 1-year glomerular filtration rate was markedly different between the 4 patient groups. The 1-year posttransplantation glucose level was higher among obese patients compared with the other groups. A multivariate regression analysis confirmed the association of a higher 1-year GFR with obesity (BMI ⬎30.0 kg/m2). Overweight and obese recipients showed excellent long-term patient and graft survival rates. Accordingly, denying patients renal transplantation because of obesity may not be justified. ROGRESSIVE improvements in renal transplantation have been due to the introduction of newer immunosuppressive regimens and to better donor selection criteria. Increased body mass index (BMI) has been documented to be a significant risk factor for morbidity and mortality1 among end-stage renal disease patients.2 It is associated with more severe complications and worse outcomes compared with nonobese patients.3 The effect of obesity in kidney allograft survival remains controversial. An association between increased BMI and reduced patient and allograft survival in kidney transplant recipients has been suggested by some4 – 6 but not all7,8 studies. Effects of obesity have been suggested on delayed graft function (DGF),9 delayed wound healing,10 and longer hospital stay.11 Some members have questioned the significance of obesity and whether it should be considered when selecting recipients.7,11 Herein we have investigated the effect of pretransplantation BMI on patient and allograft survival rates among 137 kidney transplant recipients.
P
SUBJECTS AND METHODS Between December 1998 and December 2007, 137 adult kidney transplant recipients were subgrouped into Group I (BMI ⬍18.5; n ⫽ 10), Group II (BMI 18.5–24.9; n ⫽ 62), Group III (BMI 25.0 –29.9; n ⫽ 47), and Group IV (BMI ⬎30.0; n ⫽ 16). Recipient mean age, © 2010 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710 Transplantation Proceedings, 42, 785–788 (2010)
recipient gender, and donor- recipient blood groups (identical/ compatible) were significantly different between the four patient groups (P ⬍ .001). Donor age, donor gender, donor-recipient relationship, duration of pretransplantation dialysis, HLA AB-DR matching, presensitization, and indications for kidney transplantation (chronic glomerulonephritis, chronic pyelonephritis, polycystic kidney disease, retransplantation, focal segmental glomerulosclerosis, arterial hypertension, Berger disease, interstitial nephritis, diabetes, and others) were similar among the 4 patient groups. Induction therapy was instituted for 6 patients (60.0%) in Group I, 53 patients (85.4%) in Group II, 39 patients (83.0%) in Group III, and 14 patients (87.5%) in Group IV. It consisted of Daclizumab, which was administered as 2 doses (0/2/1/0) or 1 dose (3/21/16/6), or antithymocyte globulin Fresenius (ATG-F) given as a bolus (3/18/ 16/6) or as an extended regimen (0/11/6/2) in Group I/Group II/Group III/Group IV patients, respectively (P ⫽ not significant [NS]). MainFrom the Department of Surgery (M.M.A.-J., N.N., J.S.), Sacre’Coeur Hospital, Baabda-Hazmieh, Lebanon; Department of Surgery (R.N., M.H.), Lebanese Hospital, Beirut, Lebanon; and Department of Medical Biochemistry (W.Y.A.), College of Medicine & Medical Sciences, Arabian Gulf University, Manama, Bahrain. Address reprint requests to Wassim Y. Almawi, PhD, Department of Medical Biochemistry, College of Medicine & Medical Sciences, Arabian Gulf University, PO Box 22979, Manama, Bahrain. E-mail: [email protected] 0041-1345/10/$–see front matter doi:10.1016/j.transproceed.2010.03.026 785
786
ABOU-JAOUDE, NAWFAL, NAJM ET AL Table 1. Main Outcomes Outcome
Group I (n ⫽ 10) (BMI ⬍18.5)
Group II (n ⫽ 62) (BMI 18.5–24.9)
Group III (n ⫽ 47) (BMI 25.0–29.9)
Group IV (n ⫽ 16) (BMI ⬎ 30.0)
P*
10 (100.0) 10 (100.0) 0 (0.0) 0 (0.0) 1 (10.0) 1 (10.0) 9.8 ⫾ 2.7 6 (9)§ 3 (3) 4 (6) 1 (10.0) 2 (20.0)
61 (98.4) 62 (100.0) 4 (6.5) 1 (1.6) 15 (24.2) 8 (12.9) 12.1 ⫾ 3.6 30 (38) 20 (23) 11 (15) 35 (56.4) 33 (53.2)
44 (93.6) 45 (95.7) 5 (10.6) 5 (10.6) 13 (27.7) 6 (12.8) 14.4 ⫾ 7.7 25 (50) 20 (27) 12 (23) 33 (70.2) 28 (59.5)
16 (100.0) 16 (100.0) 1 (6.3) 2 (12.5) 5 (31.3) 0 (0.0) 13.1 ⫾ 3.2 8 (17) 3 (3) 6 (14) 10 (62.5) 10 (62.5)
NS‡ NS NS NS NS NS .041 NS NS NS .005 .042
†
Graft survival Patient survival† Slow graft function† Delayed graft function† Acute Rejection† Surgical Complication† Hospital Stay (d) Infection Episodes (all)§ In-Hospital Infections§ Out-of-Hospital Infections§ Hypertension: pretransplant† Hypertension: posttransplant†
*Two-Tailed t-test for continuous variables; Fisher Exact Test for categorical variables. † Number of subjects (percent of total). ‡ NS, Not significant. § Number of patients (Number of infection episodes).
tenance immunosuppression used consisted of Neoral (Novartis, East Hanover, NJ) or Prograf/tacrolimus (Astellas Pharma Ltd, Middlesex, UK) combined with an anti-metabolite (MMF; Roche, Nutley, NJ) or Azathioprine (GlaxoSmithKline, Middlesex, UK), Prednisone, or Rapamune (Wyeth, Madison, NJ). The type and frequency of maintenance immunosuppression regimens were comparable between the 4 groups (P ⫽ NS). Statistical analysis was performed using SPSS v. 15.0 software (SPSS, Chicago, Ill, United States). Quantitative data are described as mean values ⫾ SD, whereas categorical data are presented as percentages. The end points of the study were the rate and severity of acute rejection episodes, as well as graft survival and function. Continuous variables were compared between the groups using two-tailed unpaired Student t test. Analysis of variance (ANOVA) was used to assess the significance between the 4 patient groups.
RESULTS Main Outcomes
Excellent 1-year actuarial patient and graft survival-rates were observed in all 4 groups (Table 1); the cases of death
in Group III were not related to graft dysfunction or allograft rejection on univariate analysis. A progressive increase in the prevalence of pretransplantation and posttransplantation hypertension was noted according to the increased BMI (Table 1). Longer hospital stays (days) were recorded for overweight and obese patients compared with underweight or normal-weight patients (P ⫽ .041). The number of surgical complications and in-hospital and outof-hospital infection rates were similar between the 4 patient groups; the majority of the infections were bacterial. An acute rejection episode occurred in 1 patient in Group I, 15 patients in Group II, 13 patients in Group III, and 5 patients in Group IV (P ⫽ NS; Table 1). The timing of the episode and the need for ATG-F therapy were comparable between the 4 groups. The incidence of slow graft function (SGF) or of DGF was comparable among the 4 groups (P ⫽ NS). A marked increase in 1-, 3-, 6-, and 12-month postdischarge GFR was observed among the 4 patient groups (P ⬍ .001; Table 2).
Table 2. Metabolic Profile Characteristic
GFR (mL/min)†
Fasting glucose† Cholesterol (mg/dL) Triglycerides (mg/dL) Hemoglobin levels‡ *Two-tailed t test. † Concentration in mg/dL. ‡ Concentration in g/dL.
Category
Group I (n ⫽ 10) (BMI ⬍18.5)
Group II (n ⫽ 62) (BMI 18.5–24.9)
Group III (n ⫽ 47) (BMI 25.0–29.9)
Group IV (n ⫽ 16) (BMI ⬎ 30.0)
Upon discharge Postdischarge: 1 mo Postdischarge: 3 mo Postdischarge: 6 mo At 1 y Pretransplant Posttransplant: 1y Pretransplant Posttransplant: 1y Pretransplant Posttransplant: 1y Pretransplant Posttransplant
60.3 ⫾ 14.9 69.1 ⫾ 16.7 70.0 ⫾ 18.3 67.9 ⫾ 19.3 69.4 ⫾ 18.7 83.0 ⫾ 9.7 82.5 ⫾ 9.2 189.5 ⫾ 48.9 202.8 ⫾ 46.6 175.4 ⫾ 61.6 200.7 ⫾ 102.7 10.4 ⫾ 1.3 7.1 ⫾ 2.1
69.9 ⫾ 26.4 68.5 ⫾ 23.1 71.3 ⫾ 25.0 75.3 ⫾ 24.7 76.63 ⫾ 20.6 90.7 ⫾ 19.2 99.9 ⫾ 29.5 179.8 ⫾ 52.8 212.7 ⫾ 52.9 175.1 ⫾ 99.0 210.6 ⫾ 118.5 10.7 ⫾ 1.5 7.2 ⫾ 1.7
63.2 ⫾ 24.2 63.4 ⫾ 17.3 70.2 ⫾ 18.0 75.5 ⫾ 19.5 76.9 ⫾ 21.5 91.0 ⫾ 12.7 99.2 ⫾ 17.9 197.7 ⫾ 49.7 205.4 ⫾ 47.6 224.4 ⫾ 121.0 198.7 ⫾ 98.4 10.8 ⫾ 1.9 7.5 ⫾ 1.9
92.9 ⫾ 27.0 88.8 ⫾ 19.7 102.0 ⫾ 34.1 111.6 ⫾ 35.5 111.8 ⫾ 31.2 105.1 ⫾ 53.4 123.0 ⫾ 65.6 181.7 ⫾ 45.3 188.4 ⫾ 35.4 211.0 ⫾ 112.9 165.2 ⫾ 75.9 10.4 ⫾ 1.6 7.1 ⫾ 1.6
P*
⬍.001
NS .018 NS NS NS NS NS NS
PRETRANSPLANTATION BMI
787 Table 3. Regression Analysis Group IV (BMI ⬎ 30.0)
Group III (BMI 25.0–29.9) Factor
P
OR (95% CI)
P
OR (95% CI)
Hospital Stay Pre-transplant hypertension Post-transplant hypertension Post-transplant hyperglycemia GFR: On discharge At 1 mo At 3 mo At 6 mo At 1 y
0.168 0.305 0.432 0.754 0.510 0.265 0.247 0.596 0.669
1.06 (0.98–1.16) 1.63 (0.64–4.14) 1.43 (0.58–3.52) 1.00 (0.98–1.02) 0.99 (0.96–1.02) 0.98 (0.94–1.02) 1.03 (0.98–1.08) 1.01 (0.97–1.06) 0.99 (0.96–1.03)
0.965 0.983 0.732 0.968 0.081 0.429 0.875 0.986 0.047
1.01 (0.82–1.24) 0.98 (0.20–4.83) 0.77 (0.17–3.47) 1.00 (0.98–1.02) 1.03 (1.00–1.07) 0.98 (0.92–1.04) 1.00 (0.93–1.06) 1.00 (0.94–1.06) 1.06 (1.00–1.13)
Metabolic Profile
Pretransplantation and 12-month posttransplantation hemoglobin levels and the need for transfusions were similar between the 4 patient groups (Table 2). While the 1-year posttransplantation cholesterol and triglyceride levels were higher compared with posttransplantation levels, there were no significant differences in either pretransplantation or 1-year posttransplantation cholesterol and triglyceride levels among the 4 groups (P ⫽ NS). Furthermore, 1-year posttransplantation glucose levels were higher in obese patients compared with other patient groups (Table 2). Regression Analysis
The effect of pretransplantation recipient BMI on kidney allograft survival and function was examined using multivariate regression analysis. Taking normal BMI group as a reference, multivariate analysis demonstrated no association between hospital stay, pretransplantation and posttransplantation hypertension, posttransplantation hyperglycemia, and changes in GFR among overweight (BMI ⬎25 kg/m2 ⬍ 30 kg/m2) patients. Among obese patients (BMI ⬎30 kg/m2), multivariate regression analysis showed a positive association with an increased 1-year GFR (P ⫽ .047; odds ratio [OR; 95% confidence interval (CI)] ⫽ 1.06 [1.01–1.13]) (Table 3). DISCUSSION
The impact of increased BMI on kidney transplant outcomes has previously been inconsistently reported as reduced allograft survival3,4,6 and increased mortality,5 or no effect.7,8,11 But obesity is linked to mild postoperative complications, including delayed hospital discharge,11 delayed wound healing,10 and DGF.8 In this study, overweight and obesity were associated with longer hospital stays, in agreement with an earlier study of 247 kidney transplant recipients.11 Recipient BMI did not affect posttransplantation kidney function because SGF and DGF rates were comparable between the 4 patient groups. This observation agreed with some7,8,11 but not all studies.4,6,9,12 The conflicting findings might be attributed to differences in sample size,12 patient stratification,4,12 or length of follow-up.6,9,12
Our results showed significant progressive improvements in 1-year posttransplantation GFR among the 4 patient groups, which was confirmed using regression analysis. This observation agrees with a recent study that demonstrated that higher BMI was independently associated with greater 1-year posttransplantation GFR.13 It is in apparent disagreement with other studies that claimed that obesity was linked to poor kidney function,4,6,7 which was likely due to the inclusion of patients with a large BMI (and greater muscle mass), which resulted in higher serum creatinine levels (GFR). Our findings were reminiscent of those of Sancho et al, namely, posttransplantation hyperglycemia and hypertension were more frequent among obese patients.14 There were a few important differences between our study and that of Sancho et al, namely, the serum lipid profile was comparable for all BMI categories in our study. It should be noted that in their study overweight patients were older than normal-weight patients, had a greater number of cardiovascular risk factors, and showed a higher incidence of acute tubular necrosis without higher rates of acute rejection episodes.14 In conclusion, pretransplantation BMI does not constitute a significant determinant of posttransplantation patient and allograft survivals. The only significant adverse effect of increased BMI on kidney transplant outcomes was an increased hospital stay, together with an increased prevalence of hypertension and hyperglycemia, all of which were manageable and thus of minor consequence. However, multivariate analysis confirmed the association of only higher 1-year posttransplantation GFR among obese patients. Accordingly, overweight and obese recipients can have excellent long-term patient and graft survivals comparable with those of normal-weight patients. Thus, denying patients renal transplantation because of obesity may not be justified. The effect of obesity on associated clinical outcomes should be evaluated in a larger prospective study.
REFERENCES 1. Calle EE, Thun MJ, Petrelli JM, et al: Body-mass index and mortality in a prospective cohort of U.S. adults. N Engl J Med 341:1097, 1999
788 2. Ogden CL, Carroll MD, Curtin LR, et al: Prevalence of overweight and obesity in the United States, 1999 –2004. JAMA 295:1549, 2006 3. Gore JL, Pham PT, Danovitch GM, et al: Obesity and outcome following renal transplantation. Am J Transplant 6:357, 2006 4. Meier-Kriesche H, 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 73:70, 2002 5. McDonald SP, Collins JF, Johnson DW: Obesity is associated with worse peritoneal dialysis outcomes in the Australia and New Zealand patient populations. J Am Soc Nephrol 14:2894, 2003 6. Raiss-Jalali GA, Mehdizadeh AR, Razmkon A, et al: Effect of body mass index at time of transplantation and weight gain after transplantation on allograft function in kidney transplant recipients in Shiraz. Transplant Proc 37:2998, 2005 7. Chang SH, Coates PT, McDonald SP: Effects of body mass index at transplant on outcomes of kidney transplantation. Transplantation 84:981, 2007
ABOU-JAOUDE, NAWFAL, NAJM ET AL 8. Massarweh NN, Clayton JL, Mangum CA, et al: High body mass index and short and long term renal allograft survival in adults. Transplantation 80:1430, 2005 9. Reese PP, Feldman HI, Asch DA, et al: Short-term outcomes for obese live kidney donors and their recipients. Transplantation 88:662, 2009 10. Johnson DW, Isbel NM, Brown AM, et al: The effect of obesity on renal transplant outcomes. Transplantation 74:675, 2002 11. Marks WH, Florence LS, Chapman PH, et al: Morbid obesity is not a contraindication to kidney transplantation. Am J Surg 187:635, 2004 12. Cacciola RA, Pujar K, Ilham MA, et al: Effect of degree of obesity on renal transplant outcome. Transplant Proc 40:3408, 2008 13. Bosma RJ, Kwakernaak AJ, van der Heide JJ, et al: Body mass index and glomerular hyperfiltration in renal transplant recipients: cross-sectional analysis and long- term impact. Am J Transplant 7:645, 2007 14. Sancho A, Avila A, Gavela E, et al: Effect of overweight on kidney transplantation outcome. Transplant Proc 39:2202, 2007
P
SUBJECTS AND METHODS Between December 1998 and December 2007, 137 adult kidney transplant recipients were subgrouped into Group I (BMI ⬍18.5; n ⫽ 10), Group II (BMI 18.5–24.9; n ⫽ 62), Group III (BMI 25.0 –29.9; n ⫽ 47), and Group IV (BMI ⬎30.0; n ⫽ 16). Recipient mean age, © 2010 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710 Transplantation Proceedings, 42, 785–788 (2010)
recipient gender, and donor- recipient blood groups (identical/ compatible) were significantly different between the four patient groups (P ⬍ .001). Donor age, donor gender, donor-recipient relationship, duration of pretransplantation dialysis, HLA AB-DR matching, presensitization, and indications for kidney transplantation (chronic glomerulonephritis, chronic pyelonephritis, polycystic kidney disease, retransplantation, focal segmental glomerulosclerosis, arterial hypertension, Berger disease, interstitial nephritis, diabetes, and others) were similar among the 4 patient groups. Induction therapy was instituted for 6 patients (60.0%) in Group I, 53 patients (85.4%) in Group II, 39 patients (83.0%) in Group III, and 14 patients (87.5%) in Group IV. It consisted of Daclizumab, which was administered as 2 doses (0/2/1/0) or 1 dose (3/21/16/6), or antithymocyte globulin Fresenius (ATG-F) given as a bolus (3/18/ 16/6) or as an extended regimen (0/11/6/2) in Group I/Group II/Group III/Group IV patients, respectively (P ⫽ not significant [NS]). MainFrom the Department of Surgery (M.M.A.-J., N.N., J.S.), Sacre’Coeur Hospital, Baabda-Hazmieh, Lebanon; Department of Surgery (R.N., M.H.), Lebanese Hospital, Beirut, Lebanon; and Department of Medical Biochemistry (W.Y.A.), College of Medicine & Medical Sciences, Arabian Gulf University, Manama, Bahrain. Address reprint requests to Wassim Y. Almawi, PhD, Department of Medical Biochemistry, College of Medicine & Medical Sciences, Arabian Gulf University, PO Box 22979, Manama, Bahrain. E-mail: [email protected] 0041-1345/10/$–see front matter doi:10.1016/j.transproceed.2010.03.026 785
786
ABOU-JAOUDE, NAWFAL, NAJM ET AL Table 1. Main Outcomes Outcome
Group I (n ⫽ 10) (BMI ⬍18.5)
Group II (n ⫽ 62) (BMI 18.5–24.9)
Group III (n ⫽ 47) (BMI 25.0–29.9)
Group IV (n ⫽ 16) (BMI ⬎ 30.0)
P*
10 (100.0) 10 (100.0) 0 (0.0) 0 (0.0) 1 (10.0) 1 (10.0) 9.8 ⫾ 2.7 6 (9)§ 3 (3) 4 (6) 1 (10.0) 2 (20.0)
61 (98.4) 62 (100.0) 4 (6.5) 1 (1.6) 15 (24.2) 8 (12.9) 12.1 ⫾ 3.6 30 (38) 20 (23) 11 (15) 35 (56.4) 33 (53.2)
44 (93.6) 45 (95.7) 5 (10.6) 5 (10.6) 13 (27.7) 6 (12.8) 14.4 ⫾ 7.7 25 (50) 20 (27) 12 (23) 33 (70.2) 28 (59.5)
16 (100.0) 16 (100.0) 1 (6.3) 2 (12.5) 5 (31.3) 0 (0.0) 13.1 ⫾ 3.2 8 (17) 3 (3) 6 (14) 10 (62.5) 10 (62.5)
NS‡ NS NS NS NS NS .041 NS NS NS .005 .042
†
Graft survival Patient survival† Slow graft function† Delayed graft function† Acute Rejection† Surgical Complication† Hospital Stay (d) Infection Episodes (all)§ In-Hospital Infections§ Out-of-Hospital Infections§ Hypertension: pretransplant† Hypertension: posttransplant†
*Two-Tailed t-test for continuous variables; Fisher Exact Test for categorical variables. † Number of subjects (percent of total). ‡ NS, Not significant. § Number of patients (Number of infection episodes).
tenance immunosuppression used consisted of Neoral (Novartis, East Hanover, NJ) or Prograf/tacrolimus (Astellas Pharma Ltd, Middlesex, UK) combined with an anti-metabolite (MMF; Roche, Nutley, NJ) or Azathioprine (GlaxoSmithKline, Middlesex, UK), Prednisone, or Rapamune (Wyeth, Madison, NJ). The type and frequency of maintenance immunosuppression regimens were comparable between the 4 groups (P ⫽ NS). Statistical analysis was performed using SPSS v. 15.0 software (SPSS, Chicago, Ill, United States). Quantitative data are described as mean values ⫾ SD, whereas categorical data are presented as percentages. The end points of the study were the rate and severity of acute rejection episodes, as well as graft survival and function. Continuous variables were compared between the groups using two-tailed unpaired Student t test. Analysis of variance (ANOVA) was used to assess the significance between the 4 patient groups.
RESULTS Main Outcomes
Excellent 1-year actuarial patient and graft survival-rates were observed in all 4 groups (Table 1); the cases of death
in Group III were not related to graft dysfunction or allograft rejection on univariate analysis. A progressive increase in the prevalence of pretransplantation and posttransplantation hypertension was noted according to the increased BMI (Table 1). Longer hospital stays (days) were recorded for overweight and obese patients compared with underweight or normal-weight patients (P ⫽ .041). The number of surgical complications and in-hospital and outof-hospital infection rates were similar between the 4 patient groups; the majority of the infections were bacterial. An acute rejection episode occurred in 1 patient in Group I, 15 patients in Group II, 13 patients in Group III, and 5 patients in Group IV (P ⫽ NS; Table 1). The timing of the episode and the need for ATG-F therapy were comparable between the 4 groups. The incidence of slow graft function (SGF) or of DGF was comparable among the 4 groups (P ⫽ NS). A marked increase in 1-, 3-, 6-, and 12-month postdischarge GFR was observed among the 4 patient groups (P ⬍ .001; Table 2).
Table 2. Metabolic Profile Characteristic
GFR (mL/min)†
Fasting glucose† Cholesterol (mg/dL) Triglycerides (mg/dL) Hemoglobin levels‡ *Two-tailed t test. † Concentration in mg/dL. ‡ Concentration in g/dL.
Category
Group I (n ⫽ 10) (BMI ⬍18.5)
Group II (n ⫽ 62) (BMI 18.5–24.9)
Group III (n ⫽ 47) (BMI 25.0–29.9)
Group IV (n ⫽ 16) (BMI ⬎ 30.0)
Upon discharge Postdischarge: 1 mo Postdischarge: 3 mo Postdischarge: 6 mo At 1 y Pretransplant Posttransplant: 1y Pretransplant Posttransplant: 1y Pretransplant Posttransplant: 1y Pretransplant Posttransplant
60.3 ⫾ 14.9 69.1 ⫾ 16.7 70.0 ⫾ 18.3 67.9 ⫾ 19.3 69.4 ⫾ 18.7 83.0 ⫾ 9.7 82.5 ⫾ 9.2 189.5 ⫾ 48.9 202.8 ⫾ 46.6 175.4 ⫾ 61.6 200.7 ⫾ 102.7 10.4 ⫾ 1.3 7.1 ⫾ 2.1
69.9 ⫾ 26.4 68.5 ⫾ 23.1 71.3 ⫾ 25.0 75.3 ⫾ 24.7 76.63 ⫾ 20.6 90.7 ⫾ 19.2 99.9 ⫾ 29.5 179.8 ⫾ 52.8 212.7 ⫾ 52.9 175.1 ⫾ 99.0 210.6 ⫾ 118.5 10.7 ⫾ 1.5 7.2 ⫾ 1.7
63.2 ⫾ 24.2 63.4 ⫾ 17.3 70.2 ⫾ 18.0 75.5 ⫾ 19.5 76.9 ⫾ 21.5 91.0 ⫾ 12.7 99.2 ⫾ 17.9 197.7 ⫾ 49.7 205.4 ⫾ 47.6 224.4 ⫾ 121.0 198.7 ⫾ 98.4 10.8 ⫾ 1.9 7.5 ⫾ 1.9
92.9 ⫾ 27.0 88.8 ⫾ 19.7 102.0 ⫾ 34.1 111.6 ⫾ 35.5 111.8 ⫾ 31.2 105.1 ⫾ 53.4 123.0 ⫾ 65.6 181.7 ⫾ 45.3 188.4 ⫾ 35.4 211.0 ⫾ 112.9 165.2 ⫾ 75.9 10.4 ⫾ 1.6 7.1 ⫾ 1.6
P*
⬍.001
NS .018 NS NS NS NS NS NS
PRETRANSPLANTATION BMI
787 Table 3. Regression Analysis Group IV (BMI ⬎ 30.0)
Group III (BMI 25.0–29.9) Factor
P
OR (95% CI)
P
OR (95% CI)
Hospital Stay Pre-transplant hypertension Post-transplant hypertension Post-transplant hyperglycemia GFR: On discharge At 1 mo At 3 mo At 6 mo At 1 y
0.168 0.305 0.432 0.754 0.510 0.265 0.247 0.596 0.669
1.06 (0.98–1.16) 1.63 (0.64–4.14) 1.43 (0.58–3.52) 1.00 (0.98–1.02) 0.99 (0.96–1.02) 0.98 (0.94–1.02) 1.03 (0.98–1.08) 1.01 (0.97–1.06) 0.99 (0.96–1.03)
0.965 0.983 0.732 0.968 0.081 0.429 0.875 0.986 0.047
1.01 (0.82–1.24) 0.98 (0.20–4.83) 0.77 (0.17–3.47) 1.00 (0.98–1.02) 1.03 (1.00–1.07) 0.98 (0.92–1.04) 1.00 (0.93–1.06) 1.00 (0.94–1.06) 1.06 (1.00–1.13)
Metabolic Profile
Pretransplantation and 12-month posttransplantation hemoglobin levels and the need for transfusions were similar between the 4 patient groups (Table 2). While the 1-year posttransplantation cholesterol and triglyceride levels were higher compared with posttransplantation levels, there were no significant differences in either pretransplantation or 1-year posttransplantation cholesterol and triglyceride levels among the 4 groups (P ⫽ NS). Furthermore, 1-year posttransplantation glucose levels were higher in obese patients compared with other patient groups (Table 2). Regression Analysis
The effect of pretransplantation recipient BMI on kidney allograft survival and function was examined using multivariate regression analysis. Taking normal BMI group as a reference, multivariate analysis demonstrated no association between hospital stay, pretransplantation and posttransplantation hypertension, posttransplantation hyperglycemia, and changes in GFR among overweight (BMI ⬎25 kg/m2 ⬍ 30 kg/m2) patients. Among obese patients (BMI ⬎30 kg/m2), multivariate regression analysis showed a positive association with an increased 1-year GFR (P ⫽ .047; odds ratio [OR; 95% confidence interval (CI)] ⫽ 1.06 [1.01–1.13]) (Table 3). DISCUSSION
The impact of increased BMI on kidney transplant outcomes has previously been inconsistently reported as reduced allograft survival3,4,6 and increased mortality,5 or no effect.7,8,11 But obesity is linked to mild postoperative complications, including delayed hospital discharge,11 delayed wound healing,10 and DGF.8 In this study, overweight and obesity were associated with longer hospital stays, in agreement with an earlier study of 247 kidney transplant recipients.11 Recipient BMI did not affect posttransplantation kidney function because SGF and DGF rates were comparable between the 4 patient groups. This observation agreed with some7,8,11 but not all studies.4,6,9,12 The conflicting findings might be attributed to differences in sample size,12 patient stratification,4,12 or length of follow-up.6,9,12
Our results showed significant progressive improvements in 1-year posttransplantation GFR among the 4 patient groups, which was confirmed using regression analysis. This observation agrees with a recent study that demonstrated that higher BMI was independently associated with greater 1-year posttransplantation GFR.13 It is in apparent disagreement with other studies that claimed that obesity was linked to poor kidney function,4,6,7 which was likely due to the inclusion of patients with a large BMI (and greater muscle mass), which resulted in higher serum creatinine levels (GFR). Our findings were reminiscent of those of Sancho et al, namely, posttransplantation hyperglycemia and hypertension were more frequent among obese patients.14 There were a few important differences between our study and that of Sancho et al, namely, the serum lipid profile was comparable for all BMI categories in our study. It should be noted that in their study overweight patients were older than normal-weight patients, had a greater number of cardiovascular risk factors, and showed a higher incidence of acute tubular necrosis without higher rates of acute rejection episodes.14 In conclusion, pretransplantation BMI does not constitute a significant determinant of posttransplantation patient and allograft survivals. The only significant adverse effect of increased BMI on kidney transplant outcomes was an increased hospital stay, together with an increased prevalence of hypertension and hyperglycemia, all of which were manageable and thus of minor consequence. However, multivariate analysis confirmed the association of only higher 1-year posttransplantation GFR among obese patients. Accordingly, overweight and obese recipients can have excellent long-term patient and graft survivals comparable with those of normal-weight patients. Thus, denying patients renal transplantation because of obesity may not be justified. The effect of obesity on associated clinical outcomes should be evaluated in a larger prospective study.
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