Obesity in kidney transplant recipients: association with decline in glomerular filtration rate

Effect of Recipient Body Mass Index on Kidney Transplantation Outcomes: A Systematic Review and Meta-analysis by the Transplant Committee from the French Association of Urology

CONTEXT

The impact of recipient obesity on kidney transplantation (KT) outcomes remains unclear.

OBJECTIVE

The aim of this study was to perform a systematic review and meta-analysis to appraise all available evidence on the outcomes of KT in obese patients (body mass index [BMI] ≥30 kg/m2) versus nonobese patients (BMI <30 kg/m2).

EVIDENCE ACQUISITION

A systematic review and meta-analysis was performed. Search was conducted in the MEDLINE OvidSP, Web of Science, Google Scholar, Embase, and Cochrane databases to identify all studies reporting the outcomes of KT in obese versus nonobese recipients.

EVIDENCE SYNTHESIS

Fifty-two articles met the inclusion criteria. Delayed graft function and surgical complications were significantly higher in obese recipients (delayed graft function: relative risk [RR]: 1.44, 95% confidence interval [CI]: 1.32-1.57, p < 0.01; surgical complications: RR: 1.74, 95% CI: 1.36-2.22, p < 0.0001). Five-year patient survival (RR: 0.96, 95% CI: 0.92-1.00, p = 0.01), 10-yr patient survival (RR: 0.90, 95% CI: 0.84-0.97, p = 0.006), and 10-yr graft survival (RR: 0.87, 95% CI: 0.79-0.96, p = 0.01) were significantly inferior in the obese group.

CONCLUSIONS

KT in obese recipients was associated with lower patient and graft survival, and higher delayed graft function, acute rejection, and medical and surgical complications than nonobese recipients. In the current situation of organ shortage and increasing prevalence of obesity, ways to optimize KT in this setting should be investigated.

PATIENT SUMMARY

Compared with nonobese population, kidney transplantation in obese recipients has inferior patient and graft survival, and higher medical and surgical complications.

Effect of Pre-Transplant Recipient Underweight on the Postoperative Outcome and Graft Survival in Primary Kidney Transplantation

BACKGROUND

The objective of this study was to evaluate the influence of recipient underweight on the short- and long-term outcomes of patients undergoing primary kidney transplantation (KT).

PATIENTS AND METHODS

Three hundred thirty-three patients receiving primary KT in our department between 1993 and 2017 were included in the study. Patients were divided according to their body mass index (BMI) into underweight (BMI <18.5 kg/m2; N = 29) and normal weight (BMI 18.5-24.9 kg/m2; N = 304) groups. Clinicopathological characteristics, postoperative outcomes, and graft and patient survival were analyzed retrospectively.

RESULTS

The postoperative rate of surgical complications and renal function were comparable between the groups. One year and 3 years after KT, 70% and 92.9%, respectively, of the pre-transplant underweight patients reached a normal BMI (≥18.5 kg/m2). The mean death-censored graft survival was significantly lower in pre-transplant underweight patients than in pre-transplant normal-weight patients (11.5 ± 1.6 years vs 16.3 ± 0.6 years, respectively; P = .045). Especially KT recipients with a moderate or severe pre-transplant underweight (BMI <17 kg/m2; N = 8) showed an increased rate of graft loss (5- and 10-year graft survival: 21.4% each). No statistical difference could be observed between the 2 groups regarding causes of graft loss. In multivariate analysis, recipient underweight (P = .024) remained an independent prognostic factor for graft survival.

CONCLUSION

Being underweight did not affect the early postoperative outcome after primary KT. However, underweight, and especially moderate and severe thinness, is associated with reduced long-term kidney graft survival, and therefore this group of patients should be monitored with special attention.

Recipient obesity as a risk factor in kidney transplantation

BACKGROUND

The aim of the study was to investigate the effect of recipient obesity on the short- and long-term outcomes of patients undergoing primary kidney transplantation (KT).

PATIENTS AND METHODS

A total of 578 patients receiving primary KT in our department between 1993 and 2017 were included in the study. Patients were divided according to their body mass index (BMI) into normal weight (BMI 18.5-24.9 kg/m2; N = 304), overweight (BMI 25-29.9 kg/m2; N = 205) and obese (BMI ≥ 30 kg/m2; N = 69) groups. Their clinicopathological characteristics, outcomes, and survival rates were analyzed retrospectively.

RESULTS

Obesity was associated with an increased rate of surgical complications such as wound infection (P < 0.001), fascial dehiscence (P = 0.023), and lymphoceles (P = 0.010). Furthermore, the hospital stay duration was significantly longer in the groups with obese patients compared to normal weight and overweight patients (normal weight: 22 days, overweight: 25 days, and obese: 33 days, respectively; P < 0.001). Multivariate analysis showed that recipient obesity (BMI ≥ 30) was an independent prognostic factor for delayed graft function (DGF) (OR 2.400; 95% CI, 1.365-4.219; P = 0.002) and postoperative surgical complications (OR 2.514; 95% CI, 1.230-5.136; P = 0.011). The mean death-censored graft survival was significantly lower in obese patients (normal weight: 16.3 ± 0.6 years, overweight: 16.3 ± 0.8 years, obese 10.8 ± 1.5 years, respectively; P = 0.001). However, when using the Cox proportional hazards model, the association between recipient obesity and death-censored renal graft failure disappeared, after adjustment for important covariates, whereas the principal independent predictors of graft loss were recipient diabetes mellitus and hypertension and kidneys from donors with expanded donor criteria.

CONCLUSION

In conclusion, obesity increases the risk of DGF and post-operative surgical complications after primary KT. Appropriate risk-adapted information concerning this must be provided to such patients before KT. Furthermore, obesity-typical concomitant diseases seem to negatively influence graft survival and need to be considered after the transplantation of obese patients.

Nonlinear relationship between body mass index and clinical outcomes after kidney transplantation: A dose-response meta-analysis of 50 observational studies

BACKGROUND

Exact dose-response relationship between body mass index at transplantation and clinical outcomes after kidney transplantation remained unclear, and no specific body mass index threshold and pretransplant weight loss aim were recommended for kidney transplantation candidates among transplant centers.

METHODS

PubMed, Embase, Web of Science, and Cochrane Library were searched for literature published up to December 31, 2019. The two-stage, random effect meta-analysis was performed to estimate the dose-response relationship between body mass index and clinical outcomes after kidney transplantation.

RESULTS

Ninety-four studies were included for qualitative assessment and 50 for dose-response meta-analyses. There was a U-shaped relationship between graft loss, patient death, and body mass index. Body mass index with the lowest risk of graft loss was 25.2 kg/m², and preferred body mass index range was 22-28 kg/m². Referring to a body mass index of 22 kg/m², the risk of graft loss was 1.088, 0.981, 1.003, and 1.685 for a body mass index of 18, 24, 28, and 40 kg/m², respectively. Body mass index with the lowest risk of patient death was 24.7 kg/m², and preferred body mass index range was 22-27 kg/m². Referring to a body mass index of 22 kg/m², the patient death risk was 1.115, 0.981, 1.032, and 2.634 for a body mass index of 18, 24, 28, and 40 kg/m², respectively. J-shaped relationships were observed between body mass index and acute rejection, delayed graft function, primary graft nonfunction, and de novo diabetes. Pair-wise comparisons showed that higher body mass index was also a risk factor for cardiovascular diseases, hypertension, infection, longer length of hospital stay, and lower estimated glomerular filtration rate level.

CONCLUSION

Underweight and severe obesity at transplantation are associated with a significantly increased risk of graft loss and patient death. A target body mass index at kidney transplantation is 22-27 kg/m².

Incidence and Risk Factors of Obesity in Childhood Solid-Organ Transplant Recipients

BACKGROUND

Obesity is a significant public health concern; however, the incidence post solid-organ transplantation is not well reported.

METHODS

This study determined the incidence and risk factors of obesity among pediatric solid-organ transplant recipients (heart, lung, liver, kidney, multiorgan) at The Hospital for Sick Children (2002-2011), excluding prevalent obesity. Follow-up occurred from transplantation until development of obesity, last follow-up, or end of study. Incidence of obesity was determined overall, by baseline body mass index, and organ group. Risk factors were assessed using Cox proportional-hazards regression.

RESULTS

Among 410 (55% male) children, median transplant age was 8.9 (interquartile range [IQR]: 1.0-14.5) years. Median follow-up time was 3.6 (IQR: 1.5-6.4) years. Incidence of obesity was 65.2 (95% confidence interval [CI]: 52.7-80.4) per 1000 person-years. Overweight recipients had a higher incidence, 190.4 (95% CI: 114.8-315.8) per 1000 person-years, than nonoverweight recipients, 56.1 (95% CI: 44.3-71.1). Cumulative incidence of obesity 5-years posttransplant was 24.1%. Kidney relative to heart recipients had the highest risk (3.13 adjusted hazard ratio [aHR]; 95% CI: 1.53-6.40) for obesity. Lung and liver recipients had similar rates to heart recipients. Those with higher baseline body mass index (z-score; 1.72 aHR; 95% CI: 1.39-2.14), overweight status (2.63 HR; 95% CI: 1.71-4.04), and younger transplant age (y; 1.18 aHR; 95% CI: 1.12-1.25) were at highest risk of obesity. Higher cumulative steroid dosage (per 10 mg/kg) was associated with increased risk of obesity after adjustment.

CONCLUSIONS

Among all transplanted children at The Hospital for Sick Children, 25% developed obesity within 5-years posttransplant. Kidney recipients, younger children, those overweight at transplant, and those with higher cumulative steroid use (per 10 mg/kg) were at greatest risk. Early screening and intervention for obesity are important preventative strategies.

Prediabetes and older age increase the risk of post-transplantation diabetes mellitus: Qatar experience

Post-transplantation diabetes mellitus (PTDM) is a major complication in kidney transplant recipients leading to reduced allograft and patient survival. Given the high prevalence of diabetes in Qatar, which is twice the global average, we were interested in determining the incidence of PTDM, identifying risk factors, and comparing clinical outcomes in kidney transplant recipients with and without diabetes. We retrospectively followed up 191 adult kidney allograft recipients transplanted between January 1, 2012, and December 31, 2016, for a median of 41 months. A total of 76 patients (40%) had pre-existing diabetes. A total of 39 patients developed PTDM during follow-up; they represent 34% of patients who did not have diabetes prior to transplantation. Two thirds of PTDM occurred within 3-6 months post-transplantation. Prediabetes before transplant [OR = 6.07 (1.24-29.74), P = .026] older recipient's age at the time of transplantation [OR = 1.10 (1.00-1.20), P = .039] and average fasting blood sugar during 3-6 months post-transplant [OR = 1.06 (1.01-1.11), P = .010] were independently associated with PTDM. Patient and kidney allograft survival rates exceeded 97% in all groups. The incidence of PTDM in kidney transplant recipients living in Qatar is high. Older age and prediabetes are independent risk factors for developing PTDM.

Sleeve Gastrectomy Compared with Gastric Bypass for Morbidly Obese Patients with End Stage Renal Disease: a Decision Analysis

INTRODUCTION

The use of bariatric surgery has increased for morbidly obese patients with end stage renal disease (ESRD) for whom listing on the waitlist is often restricted until a certain BMI threshold is achieved. Effective weight loss for this population improves access to life-saving renal transplantation. However, it is unclear whether sleeve gastrectomy (SG) vs Roux-en-Y gastric bypass (RYGB) is a more effective therapy for these patients.

METHODS

A decision analytic Markov state transition model was created to simulate the life of morbidly obese patients with ESRD who were deemed ineligible to be waitlisted for renal transplantation unless they achieved a BMI less than 35 kg/m². Life expectancy following weight management (MWM), RYGB, and SG were estimated. Base case patients were defined as having a pre-intervention BMI of 45 kg/m². Sensitivity analysis of initial BMI was performed. Markov parameters were extracted from literature review.

RESULTS

RYGB improved survival compared with SG and MWM. RYGB patients had higher rates of transplantation, leading to improved mean long-term survival. Base case patients who underwent RYGB gained 1.3 additional years of life compared with patient's who underwent SG and 2.6 additional years of life compared with MWM.

CONCLUSIONS

RYGB improves access to renal transplantation and thereby increases long-term survival compared with SG and MWM. The use of SG may be incongruent with the goal of improving access to renal transplantation for morbidly obese patients.

Effects of body weight variation in obese kidney recipients: a retrospective cohort study

Background

Obese kidney allograft recipients have worse results in kidney transplantation (KT). However, there is lack of information regarding the effect of body mass index (BMI) variation after KT. The objective of the study was to evaluate the effects of body weight changes in obese kidney transplant recipients.

Methods

In this study we used data from the Catalan Renal Registry that included KT recipients from 1990 to 2011 (n = 5607). The annual change in post-transplantation BMI was calculated. The main outcome variables were delayed graft function (DGF), estimated glomerular filtration rate (eGFR) and patient and graft survival.

Results

Obesity was observed in 609 patients (10.9%) at the time of transplantation. The incidence of DGF was significantly higher in obese patients (40.4% versus 28.3%; P < 0.001). Baseline obesity was significantly associated with worse short- and long-term graft survival (P < 0.05) and worse graft function during the follow-up (P < 0.005). BMI variations in obese patients did not improve eGFR or graft or patient survival.

Conclusions

Our conclusion is that in obese patients, decreasing body weight after KT does not improve either short-term graft outcomes or long-term renal function.

Effect of Changes in Body Mass Index on Cardiovascular Outcomes in Kidney Transplant Recipients

BACKGROUND

A higher body mass index (BMI) before kidney transplantation (KT) is associated with increased mortality and allograft loss in kidney transplant recipients (KTRs). However, the effect of changes in BMI after KT on these outcomes remains uncertain. The aim of this study was to investigate the effect of baseline BMI and changes in BMI on clinical outcomes in KTRs.

METHODS

A total of 869 KTRs were enrolled from a multicenter observational cohort study from 2012 to 2015. Patients were divided into low and high BMI groups before KT based on a BMI cutoff point of 23 kg/m². Differences in acute rejection and cardiovascular disease (CVD) between the 2 groups were analyzed. In addition, clinical outcomes across the 4 BMI groups divided by BMI change 1 year after KT were compared. Associations between BMI change and laboratory findings were also evaluated.

RESULTS

Patients with a higher BMI before KT showed significantly increased CVD after KT (P = .027) compared with patients with a lower BMI. However, among the KTRs with a higher baseline BMI, only persistently higher BMI was associated with increased CVD during the follow-up period (P = .003). Patients with persistently higher BMI had significantly decreased high-density lipoprotein cholesterol and increased hemoglobin, triglyceride, and hemoglobin A1c levels. Baseline BMI and post-transplantation change in BMI were not related to acute rejection in KTRs.

CONCLUSIONS

BMI in the 1st year after KT as well as baseline BMI were associated with CVD in KTRs. More careful monitoring of obese KTRs who do not undergo a reduction in BMI after KT is required.

Association Between Overweight and Renal Transplant Outcomes: A Meta-Analysis

OBJECTIVES

As the demand for kidney transplant allografts has increased, many centers are expanding the upper limit of acceptable body mass index for kidney donors. However, obesity is a risk factor for developing renal disease. Our goal was to quantify body mass index trends in donor nephrectomy patients and to institute nutrition counseling to promote sustainable weight loss to reduce the risk of metabolic syndrome-derived renal dysfunction.

MATERIALS AND METHODS

Ninety patients who underwent donor nephrectomy between 2007 and 2012 consented to having height and weight data collected at multiple time points. After data collection, each patient underwent a standardized nutrition counseling session. One year later, body mass index was reassessed.

RESULTS

Preoperatively, 52% of the patients were overweight or obese. The percentage of overweight and obese patients remained stable for 2 years after surgery. However, at 3, 4, and 5 years after surgery, these rates increased to 59%, 69%, and 91%. Each patient was counseled about obesity-related comorbidities and provided information about lifestyle modification. One year later, 94% of previously overweight patients and 82% of previously obese patients had a decrease in mean body mass index from 27.2 ± 4.0 kg/m2 to 25.1 ± 3.6 kg/m2.

CONCLUSIONS

Living-donor nephrectomy patients are at risk of developing obesity, similar to the adult population. Nutrition counseling may be beneficial to help normalize body mass index in patients who have become overweight or obese to potentially prevent obesity-related comorbidities. All patients were evaluated by a nutrition specialist after surgery to review our donor nephrectomy nutrition brochure. Body mass index monitoring and primary care follow-up appear to be appropriate surveillance methods.

Understanding Trends in Kidney Function 1 Year after Kidney Transplant in the United States

Lower eGFR 1 year after kidney transplant is associated with shorter allograft and patient survival. We examined how practice changes in the past decade correlated with time trends in average eGFR at 1 year after kidney transplant in the United States in a cohort of 189,944 patients who received a kidney transplant between 2001 and 2013. We calculated the average eGFR at 1 year after transplant for the recipient cohort of each year using the appropriate Modification of Diet in Renal Disease equation depending on the prevailing methodology of creatinine measurement, and used linear regression to model the effects of practice changes on the national post-transplant eGFR trend. Between the 2001-2005 period and the 2011-2013 period, average 1-year post-transplant eGFR remained essentially unchanged, with differences of 1.34 (95% confidence interval, 1.03 to 1.65) ml/min per 1.73 m² and 0.66 (95% confidence interval, 0.32 to 1.01) ml/min per 1.73 m² among deceased and living donor kidney transplant recipients, respectively. Over time, the mean age of recipients increased and more marginal organs were used; adjusting for these trends unmasked a larger temporal improvement in post-transplant eGFR. However, changes in immunosuppression practice had a positive effect on average post-transplant eGFR and balanced out the negative effect of recipient/donor characteristics. In conclusion, average 1-year post-transplant eGFR remained stable, despite increasingly unfavorable attributes in recipients and donors. With an aging ESRD population and continued organ shortage, preservation of average post-transplant eGFR will require sustained improvement in immunosuppression and other aspects of post-transplant care.

Influence of Body Mass on Kidney Graft Function in Patients After Kidney Transplantation

BACKGROUND

Increasing evidence shows that body mass may play a role in complications after kidney transplantation and influence graft and patient survival. The aim of this study was to analyze the association between graft function and both the body mass and adipokines (leptin, visfatin, adiponectin) in kidney transplant recipients.

METHODS

We studied 183 kidney transplant recipients from the Department of Nephrology, Transplantology and Internal Disease, Medical University of Gdansk. Anthropometry and body composition examinations were performed using an electronic scale, hand grip dynamometer, and BCM - Body Composition Monitor (Fresenius, Germany). Obesity, overweight, and underweight were defined according to body mass index (BMI) classification. Blood urea nitrogen, creatinine, blood morphology, lipidogram, albumin, and C-reactive protein were measured. Estimated glomerular filtration rate (eGFR) was calculated according to the Chronic Kidney Disease Epidemiology Collaboration formula. Leptin, visfatin, and adiponectin were measured by ELISA methods.

RESULTS

Underweight was found in 16 (8.7%) KTR, overweight and obesity were observed in 68 (37.1%) and 26 (14.2%) patients, respectively. No relation between BMI and eGFR in all groups was noted, but in the early period after transplantation a correlation between BMI and creatinine and eGFR was observed. In all studied patients (also patients in the early posttransplantation period), eGFR significantly correlated with leptin and visfatin. Multiple regression analysis confirmed an association between eGFR and leptin and visfatin in all studied populations and between eGFR and BMI in the group examined shortly after transplantation.

CONCLUSIONS

Sarcopenic overweight and obesity prevail in KTR. In the short-term but not long-term period after transplantation, worse graft function was associated with high BMI. An association between graft function and leptin and visfatin was noted.

Absence of the Effect of Pretransplant Body Mass Index on Post Kidney Transplant Outcomes

CONTEXT

Obesity has been reported as risk factor for reduced posttransplant graft and patient survival and increased delayed graft function (DGF).

OBJECTIVE

The purpose of this work is to analyze the effect of body mass index (BMI) on defined transplant outcomes in patients transplanted under defined guidelines in a kidney transplant program.

DESIGN

Review of a prospectively collected database in renal transplant recipients receiving rabbit antithymocyte globulin induction, mycophenolate mofetil, tacrolimus, and early corticosteroid withdrawal between 2001 and 2011.

SETTING

This review was conducted in a single abdominal transplant program in the United States.

MAIN OUTCOME MEASURES

Primary outcome was death-censored graft survival categorized by posttransplant body mass groups. Secondary outcomes included DGF as well as patient survival.

RESULTS

Four hundred sixty seven patients were identified. No difference was observed in graft survival or DGF between BMI groups. One-year, death-censored graft survival and patient survival rates ranged from 97.5% to 100% and 96.6% to 100%, respectively. Delayed graft function was uncommon across all BMI groups, ranging from 5.3% to 9.1%, with the lowest incidence in patients with a BMI ≥ 35 kg/m(2). Biopsy-proven acute rejection rates at 1 year were similar across all groups (10.1%-14%) as were estimated glomerular filtration rates were at 1, 3, and 5 years.

CONCLUSION

Our results do not show an effect of BMI on posttransplant outcomes, suggesting that relaxation of BMI criteria may be warranted for recipient selection.

Obesity and graft dysfunction among kidney transplant recipients: Increased risk for atherosclerosis

Weight gain after kidney transplant is common, and may be related to graft dysfunction and high cardiovascular risk. We investigated the prevalence of obesity and evaluated the relationship between obesity and graft dysfunction in kidney transplant recipients (KTRs). All patients who received kidney transplant at the Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) between January 2005 and December 2009 were recruited. Information on demographics, clinical characteristics and post-transplant care were documented. All patients underwent transthoracic echocardiography and carotid Doppler ultrasound for the assessment of cardiac status and carotid intima-media thickness (cIMT), respectively. Inferential and modelling statistics were applied. One hundred KTRs were recruited, of which 63 were males. The mean age was 42.2 ± 12.42 years with a range of 19-70 years. The mean body mass index and waist circumference of the recipients were 26.4 ± 4.81 kg/m² and 90.73 ± 14.76 cm, respectively. Twenty-nine patients (29%) were obese; of these, 24 (82.8%) had moderate obesity, 4 (13.8%) had severe obesity, and 1 (3.4%) had morbid obesity. Graft dysfunction was present in 52%. Obese patients were older (P < 0.0001), had graft dysfunction (P = 0.03), higher mean arterial blood pressure (P = 0.022), total cholesterol (P = 0.019), triglycerides (P < 0.0001), left ventricular mass index (P = 0.035) and cIMT (P = 0.036). Logistic regression showed obesity to be independently associated with graft dysfunction (P = 0.033). Obesity after kidney transplantation is common and is associated with graft dysfunction and markers of atherosclerosis.

Adipokines and nutritional status in kidney transplant recipients

BACKGROUND

Obesity and disturbances of adipokine concentrations are often recognized in kidney transplant recipients (KTRs). Leptin plays a key role in regulating energy intake and expenditure, including appetite and hunger, metabolism, and behavior. Adiponectin modulates certain metabolic processes, including glucose regulation and fatty acid oxidation, and exerts some weight-reduction effects. Visfatin has various functions, including the promotion of vascular smooth muscle cell maturation and inhibition of neutrophil apoptosis. It also activates insulin receptors and has insulin-mimetic effects, lowering blood glucose and improving insulin sensitivity. The aim of this study was to evaluate the prevalence of leptin, adiponectin, and visfatin and nutritional status abnormalities in stable KTRs.

METHODS

Eighty KTRs aged 52.4 ± 14.0 years participated in the study. Nutritional status was determined with the use of the 7-point Subjective Global Assessment (SGA), anthropometric measurements (bioimpedance analysis), and serum concentration. Concentrations of leptin, adiponectin, and visfatin were measured with the use of enzyme-linked immunosorbent assay.

RESULTS

Mean time after transplantation and estimated glomerular filtration rate (eGFR; Modification of Diet in Renal Disease formula) were 82.5 ± 56.5 months and 42.0 ± 15.0 mL/min/1.73 m(2), respectively; 29 (36.2%) of the KTRs, despite high body mass index (BMI ≥25 kg/m(2)), presented mild malnutrition (SGA ≤5). BMI, content of body fat, and leptin concentration correlated positively with time from transplantation and negatively with eGFR. Additionally, patients with BMI ≥25 kg/m(2) presented significantly higher leptin-to-adiponectin ratios compared with lean patients (3.5 vs 1.1, respectively; P < .05). KTRs with eGFR ≥60 mL/min/1.73 m(2) presented significantly lower leptin concentration and BMI.

CONCLUSIONS

Despite high BMI, mild malnutrition was present in one-third of KTRs. Increased BMI, abdominal obesity, and high leptin concentration were aggravated by time from transplantation and deterioration of graft function. Overweight/obesity and incorrect leptin-to-adiponectin ratio could increase cardiovascular risk in KTRs.

Body mass index and outcome in renal transplant recipients: a systematic review and meta-analysis

BACKGROUND

Whether overweight or obese end stage renal disease (ESRD) patients are suitable for renal transplantation (RT) is often debated. The objective of this review and meta-analysis was to systematically investigate the outcome of low versus high BMI recipients after RT.

METHODS

Comprehensive searches were conducted in MEDLINE OvidSP, Web of Science, Google Scholar, Embase, and CENTRAL (the Cochrane Library 2014, issue 8). We reviewed four major guidelines that are available regarding (potential) RT recipients. The methodology was in accordance with the Cochrane Handbook for Systematic Reviews of Interventions and written based on the PRISMA statement. The quality assessment of studies was performed by using the GRADE tool. A meta-analysis was performed using Review Manager 5.3. Random-effects models were used.

RESULTS

After identifying 5,526 studies addressing this topic, 56 studies were included. We extracted data for 37 outcome measures (including data of more than 209,000 RT recipients), of which 26 could be meta-analysed. The following outcome measures demonstrated significant differences in favour of low BMI (<30) recipients: mortality (RR = 1.52), delayed graft function (RR = 1.52), acute rejection (RR = 1.17), 1-, 2-, and 3-year graft survival (RR = 0.97, 0.95, and 0.97), 1-, 2-, and 3-year patient survival (RR = 0.99, 0.99, and 0.99), wound infection and dehiscence (RR = 3.13 and 4.85), NODAT (RR = 2.24), length of hospital stay (2.31 days), operation duration (0.77 hours), hypertension (RR = 1.35), and incisional hernia (RR = 2.72). However, patient survival expressed in hazard ratios was in significant favour of high BMI recipients. Differences in other outcome parameters were not significant.

CONCLUSIONS

Several of the pooled outcome measurements show significant benefits for 'low' BMI (<30) recipients. Therefore, we postulate that ESRD patients with a BMI >30 preferably should lose weight prior to RT. If this cannot be achieved with common measures, in morbidly obese RT candidates, bariatric surgery could be considered.

Effects of obesity on kidney transplantation outcomes: a systematic review and meta-analysis

BACKGROUND

The effects of obesity on outcomes reported after kidney transplantation have been controversial. The purpose of this systematic review and meta-analysis was to elucidate this issue.

METHODS

MEDLINE, EMBASE, Cochrane Library, and gray literature were searched up to August 6, 2013. Studies that compared obese and nonobese patients who underwent kidney transplantation and evaluated one of these outcomes-delayed graft function (DGF), acute rejection, graft or patient survival at 1 or 5 years after transplantation, or death by cardiovascular disease (CVD)-were included. Two independent reviewers extracted the data and assessed the quality of the studies.

RESULTS

From 1,973 articles retrieved, 21 studies (9,296 patients) were included. Obesity was associated with DGF (relative risk, 1.41; 95% confidence interval, 1.26-1.57; I=8%; Pheterogeneity=0.36), but not with acute rejection. Graft loss and death were associated with obesity only in the analysis of studies that evaluated patients who received a kidney graft before year 2000. No association of obesity with graft loss and death was found in the analysis of studies that evaluated patients who received a kidney graft after year 2000. Death by CVD was associated with obesity (relative risk, 2.07; 95% confidence interval, 1.17-3.64; I=0%; Pheterogeneity=0.59); however, most studies included in this analysis evaluated patients who received a kidney graft after year 2000.

CONCLUSION

In conclusion, obese patients have increased risk for DGF. In the past years, obesity was a risk factor for graft loss, death by CVD, and all-cause mortality. However, for the obese transplanted patient today, the graft and patient survival is the same as that of the nonobese patient.