Computed Tomography Volumetric Fat Parameters versus Body Mass Index for Predicting Short-term Outcomes of Colon Surgery

Background  

At present, the impact of obesity on short-term outcomes of general surgery remains controversial, especially in the field of laparoscopy. Most studies on the subject have used the body mass index (BMI) to define obesity without distinguishing between visceral and subcutaneous storage. Computed tomography (CT) volumetric analysis permits accurate evaluation of site-specific volume of adipose tissue. The purpose of this study was to compare CT volumetric fat parameters and the BMI for predicting short-term outcomes of colon surgery.     

Impact of Pretransplant Body Mass Index on Early Kidney Graft Function

Background

An increase in the number of obese patients on transplantation waiting lists can be observed. There are conflicting results regarding the influence of body mass index (BMI) on graft function.

Methods

We performed a single-center, retrospective study of 859 adult patients who received a renal graft from deceased donors. BMI (kg/m²) was calculated from patients' height and weight at the time of transplantation. Kidney recipients were subgrouped into 4 groups, according to their BMI: Groups A (<18.5; n = 57), B (18.6–24.9; n = 565), C (25–29.9; n = 198) and D (>30; n = 39). Primary or delayed graft function (DGF), acute rejection (AR) episodes, and number of reoperations, graft function expressed by glomerular filtration rate (GFR) and serum creatinine concentration and number of graft loss as well as the recipient's death were analyzed. The follow-up period was 1 year.

Results

Obese patients' grafts do not develop any function more frequently in comparison with their nonobese counterparts (P < .0001; odds ratio [OR], 32.364; 95% CI, 2.174–941.422). Other aspects of the procedure were analyzed to confirm that thesis: Cold ischemia time and number of HLA mismatches affect the frequency of AR (OR, 1.0182 [P = .0029] and OR, 1.1496 [P = .0147], respectively); moreover, donor median creatinine serum concentration (P = .00004) and cold ischemia time (P = .00019) are related to delayed graft function. BMI did not influence the incidence of DGF (P = .08, OR; 1.167; 95% CI, 0.562–2.409), the number of AR episodes (P > .1; OR, 1.745; 95% CI, 0.846–3.575), number of reoperations, GFR (P = .22–.92), or creatinine concentration (P = .09). Number of graft losses (P = .12; OR, 1.8; 95% CI, 0.770–4.184) or patient deaths (P = .216; OR, 3.69; 95% CI, 0.153–36.444) were not influenced.

Conclusion

Greater recipient BMI at the time of transplantation has a significant influence on the incidence of primary graft failure.     

Association of Body Mass Index with Outcomes in Patients with CKD

Obesity is associated with higher mortality in the general population, but this association is reversed in patients on dialysis. The nature of the relationship of obesity with adverse clinical outcomes in nondialysis-dependent CKD and the putative interaction of the severity of disease with this association are unclear. We analyzed data from a nationally representative cohort of 453,946 United States veterans with eGFR<60 ml/min per 1.73 m². The associations of body mass index categories (<20, 20 to <25, 25 to <30, 30 to <35, 35 to <40, 40 to <45, 45 to <50, and ≥50 kg/m²) with all-cause mortality and disease progression (using multiple definitions, including incidence of ESRD, doubling of serum creatinine, and the slopes of eGFR) were examined in Cox proportional hazards models and logistic regression models. Multivariable adjustments were made for age, race, comorbidities and medications, and baseline eGFR. Body mass index showed a relatively consistent U-shaped association with clinical outcomes, with the best outcomes observed in overweight and mildly obese patients. Body mass index levels <25 kg/m² were associated with worse outcomes in all patients, independent of severity of CKD. Body mass index levels ≥35 kg/m² were associated with worse outcomes in patients with earlier stages of CKD, but this association was attenuated in those patients with eGFR<30 ml/min per 1.73 m². Thus, until clinical trials establish the ideal body mass index, a cautious approach to weight management is warranted in this patient population.Obesity defined by elevated body mass index (BMI) has been regarded as a cardiovascular risk factor in the general population.^1–4 Obesity is also associated with increased risk of incident CKD^5–9 and ESRD.^10–13 Negative effects of obesity include those effects mediated by conditions caused or worsened by it, such as diabetes mellitus (DM) or hypertension, and direct adverse metabolic effects, such as inflammation, increased synthesis of apolipoprotein B and very LDLs, increased production of insulin, and insulin resistance.¹⁴ Obesity also induces glomerular hyperfiltration,¹⁵ and weight loss in morbidly obese patients attenuates proteinuria.¹⁶However, even in relatively healthy populations, very low BMI levels have been consistently associated with higher all-cause mortality,¹⁷ and the optimal BMI for survival has varied from study to study.^18,19 Contrasting the unequivocally higher risk associated with elevated BMI in the general population, studies that examined patient groups with various chronic diseases have either found no association²⁰ or described paradoxically lower mortality associated with high BMI levels.^21,22 The reversal of the obesity–mortality association has been very robust in patients with ESRD,^23,24 but there are limited studies showing conflicting results^20,25,26 in patients with nondialysis–dependent CKD (NDD-CKD). The heterogeneity of the NDD-CKD population, which encompasses patients with kidney function ranging from near-normal to near-nil, could make it difficult to determine the role that obesity plays as a risk factor in this group and the ideal therapeutic weight management goals.We examined the association of BMI with all-cause mortality and progressive CKD in a large national cohort of United States veterans with eGFR<60 ml/min per 1.73 m².     

Body Mass Index and Adverse Perioperative Outcomes Following Hepatic Resection

Background  

The effect of obesity on perioperative outcomes following hepatic resection is not clearly defined. We sought to understand the implications of obesity on post-hepatectomy outcomes in a nationally represented cohort of patients.     

Association of Body Mass Index with Patient-Centered Outcomes in Children with ESRD

Obesity is associated with less access to transplantation among adults with ESRD. To examine the association between body mass index at ESRD onset and survival and transplantation in children, we performed a retrospective analysis of children ages 2–19 years old beginning RRT from 1995 to 2011 using the US Renal Data System. Among 13,172 children, prevalence of obesity increased from 14% to 18%, whereas prevalence of underweight decreased from 12% to 9% during this period. Over a median follow-up of 7.0 years, 10,004 children had at least one kidney transplant, and 1675 deaths occurred. Risk of death was higher in obese (hazard ratio [HR], 1.17; 95% confidence interval [95% CI], 1.03 to 1.32) and underweight (HR, 1.26; 95% CI, 1.09 to 1.47) children than children with normal body mass indices. Obese and underweight children were less likely to receive a kidney transplant (HR, 0.92; 95% CI, 0.87 to 0.97; HR, 0.83; 95% CI, 0.78 to 0.89, respectively). Obese children had lower odds of receiving a living donor transplant (odds ratio, 0.85; 95% CI, 0.74 to 0.98) if the transplant occurred within 18 months of ESRD onset. Adjustment for transplant in a time–dependent Cox model attenuated the higher risk of death in obese but not underweight children (HR, 1.09; 95% CI, 0.96 to 1.24). Lower rates of kidney transplantation may, therefore, mediate the higher risk of death in obese children with ESRD. The increasing prevalence of obesity among children starting RRT may impede kidney transplantation, especially from living donors.     

Central Body Fat Distribution Associates with Unfavorable Renal Hemodynamics Independent of Body Mass Index

Central distribution of body fat is associated with a higher risk of renal disease, but whether it is the distribution pattern or the overall excess weight that underlies this association is not well understood. Here, we studied the association between waist-to-hip ratio (WHR), which reflects central adiposity, and renal hemodynamics in 315 healthy persons with a mean body mass index (BMI) of 24.9 kg/m² and a mean ¹²⁵I-iothalamate GFR of 109 ml/min per 1.73 m². In multivariate analyses, WHR was associated with lower GFR, lower effective renal plasma flow, and higher filtration fraction, even after adjustment for sex, age, mean arterial pressure, and BMI. Multivariate models produced similar results regardless of whether the hemodynamic measures were indexed to body surface area. Thus, these results suggest that central body fat distribution, independent of BMI, is associated with an unfavorable pattern of renal hemodynamic measures that could underlie the increased renal risk reported in observational studies.Central body fat distribution is associated with increased long-term renal risk, as shown in several recent studies.^1–3 This increased risk is often attributed to associated conditions, such as weight excess, hypertension, dyslipidemia, and diabetes.^4–10 However, after adjustment for these conditions, central body fat distribution, estimated from waist-to-hip ratio (WHR), remains an independent determinant of increased long-term renal risk.^1–3 The mechanisms underlying this increased renal risk in association with a central body fat distribution are not well established. Small studies suggest that central body fat distribution is associated with an unfavorable renal hemodynamic profile;^11,12 however, these studies did not control for concomitant presence of overall weight excess as commonly reflected by body mass index (BMI), a well established determinant of an unfavorable renal hemodynamic profile in itself.^5,13 We therefore investigated whether body fat distribution is associated with renal hemodynamics, independent of BMI, in a cohort of 315 normotensive persons with normal fasting glucose levels.     

Impact of Continuous Value of Body Mass Index on Graft Loss in Overweight Patients

Introduction

High body mass index (BMI) is associated with increased cardiovascular mortality and risk of progression to end-stage renal disease both among the general population and among renal transplant patients. However, in the latter condition no unequivocal studies have been reported in the literature. The aim of our study was to investigate continuous versus categorical values of BMI (World Health Organization classification) as an independent risk factor in renal transplantation.

Patients and methods

We retrospectively studied 194 renal transplant patients (128 males and 66 females) whose mean age at transplant was 43.9 years. They had 5 years follow-up. To investigate the association between BMI and graft survival, we performed univariate and multivariate analyses using the Cox regression model. This model was adjusted both for classical covariates (age, gender, time on dialysis, HLA mismatches, donor status) and other covariates as delayed graft function (DGF), acute rejection episodes (AR), and chronic allograft nephropathy (CAN), which are universally recognized to be predictors of graft loss as evidenced by a need for dialysis treatments.

Results

At the time of transplantation, the BMI averaged 24.4 ± 2.65 kg/m². Upon univariate analysis, age (P = .049), BMI (P = .005), DGF (P = .009), ARE (P < .0001), and CAN (P = .001) were significantly related to poor transplant outcomes. Upon multivariate analysis, only the BMI value, considered as continuous value (P = .013), DGF (P = .030), and ARE (P < .0001) were significantly related to graft loss.

Conclusions

BMI as a continuous value represented an independent risk factor for renal transplant loss at 5 years. Correction of pretransplant body weight both in overweight (25 ≤ BMI ≤ 30) and normal-weight patients is essential to avoid graft loss.     

The Association of Body Mass Index with Postoperative Outcomes After Elective Paraesophageal Hernia Repair

Purpose

To evaluate the association between body mass index (BMI) and postoperative outcomes in elective paraesophageal hernia (PEH) repairs.

Methods

A retrospective review of patients who underwent elective PEH repair in the ACS NSQIP database (2005–2015) was performed. Patients were stratified into BMI groups (<?18.5, 18.5–24.9, 25.0–29.9, 30.0–34.9, 35–39.9, and ≥?40.0 kg/m²) according to the World Health Organization classification criteria. A multivariable logistic regression model was developed to characterize the association between BMI class and outcomes, including readmission, reoperation, postoperative complications, and mortality.

Results

The median (IQR) age of the 9641 patients who met inclusion criteria was 64 (55–72) and 72.7% were women. Across each BMI class, age, race, gender, type of procedure, frailty index, smoking, and ASA class varied (p?<?0.05). Underweight patients (BMI <?18.5 kg/m²) had an increased risk of mortality (OR?=?6.35, p?<?0.05). Patients with a BMI 35–39.9 kg/m² (OR?=?0.65, p?<?0.05) and ≥?40 kg/m² (OR?=?0.36, p?<?0.001) were associated with a decreased risk for readmissions.

Conclusion

Underweight patients have an increased risk for postoperative mortality after elective PEH repair. Higher BMI was associated with a diminished risk for readmission, but not for mortality, reoperations, or overall complications.

     

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.

Effect of Pretransplant Body Mass Index on Kidney Transplant Recipient and Graft Long-term Survival

BackgroundThe aim of the study was to assess the influence of pretransplant body mass index (BMI [calculated as weight in kilograms divided by height in meters squared]) to the graft and patient 5- and 10-year survival.MethodsOur study group consisted of 706 patients who received their kidney transplant after the year 2000.ResultsAlmost half, 51.9% (n = 372) of the patients had BMI < 25, and 47.6% (n = 336) had BMI ≥ 25. Patients who were overweight or obese were significantly older than other groups (P = .01). The 5-year recipient survival was significantly better in the BMI < 25 group (n = 291, 79.5%) than the BMI ≥ 25 group (n = 238, 70.2%, P < .05). In addition, 10-year recipient survival was better in the BMI < 25 group (n = 175, 47.8%) compared with the BMI ≥ 25 group (n = 127, 37.5%, P < .05). Similarly, 5-year graft survival was better in the BMI < 25 group (66.9%, n = 242) compared with the BMI ≥ 25 group (61.1%, n = 204, P < .05). However, 10-year graft survival was not statistically significant (P = .08). Regarding the impact of diabetes on survival, we found patients with diabetes mellitus to have worse survival in all groups (P = .009).ConclusionsRecipient graft survival was affected by diabetes mellitus independently from being overweight. In the current study, we demonstrated that pretransplant obesity or being overweight affects recipient and graft short-term survival, but long-term comparison of patients who were overweight or obese with patients with normal BMI revealed minimal recipient survival differences and in graft survival analysis no difference. Although in many studies obesity and being overweight predict a bad outcome for kidney transplant recipient survival, our research did not fully confirm it. Diabetes mellitus had worse outcome in all patients groups.     

Comparison of Outcomes After Single-Port Laparoscopic Cholecystectomy in Relation to Patient Body Mass Index

Background and Objectives:

Single-port laparoscopic cholecystectomy may contribute to a paradigm shift in the field of laparoscopic cholecystectomy surgery by providing patients with benefits beyond those observed after other surgical procedures. This study was designed to evaluate clinically meaningful differences in operative outcomes between obese and nonobese patients after single-port laparoscopic cholecystectomy.

Methods:

Data were collected retrospectively from 172 patients who had undergone single-port laparoscopic cholecystectomy performed by the same surgeon at a single medical center between January and December 2011. For the outcome analysis, patients were divided into nonobese and obese patient groups according to their body mass index (<25 kg/m² vs ≥25 kg/m²).

Results:

Demographic and clinical data did not differ significantly between obese patients (n = 65) and nonobese patients (n = 107). In addition, statistically significant differences pertaining to most measured surgical outcomes including postoperative hospital stay, bile spillage, additional port use, and open conversion were not detected between the groups. However, the two groups differed significantly regarding operative time such that nonobese patients had shorter operative times than obese patients (P < .05).

Conclusion:

The results of this study showed that operative time for single-port laparoscopic cholecystectomy was the only difference between obese and nonobese patients. Given this result, body mass index may not be as relevant a factor in patient selection for single-port laparoscopic cholecystectomy as previously thought.     

Body Mass Index and Outcomes from Pancreatic Resection: a Review and Meta-analysis

Introduction  

There are 1.6 billion adults worldwide who are overweight, with body mass indices (BMI) between 25 and 30, while more than 400 million are obese (BMI >30). Obesity predicts the incidence of and poor outcomes from pancreatic cancer. Obesity has also been linked to surgical complications in pancreatectomy, including increased length of hospital stay, surgical infections, blood loss, and decreased survival. However, BMI’s impact on many complications following pancreatectomy remains controversial.     

The Effect of Elevated Body Mass Index on Outcomes Following Cytoreductive Surgery with Hyperthermic Intraperitoneal Chemotherapy

Background

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) can prolong survival in peritoneal-based malignancies. These malignancies harbor in visceral and omental adipose tissue, and as a result, obesity may contribute to greater tumor burden. Obesity also is an independent risk factor for perioperative complications following major surgery. No studies to date have investigated the effect of elevated body mass index (BMI) on disease burden and perioperative outcomes in CRS-HIPEC patients.

Methods

Observational study of consecutive patients taken to the operating suite from 2007 to 2012 for CRS-HIPEC. Data were reviewed retrospectively, and patients for whom complete cytoreduction was not achieved and those with BMI <18.5 were excluded. Various operative data points, including peritoneal cancer index, surgery length, and estimated blood loss, were measured prospectively. Perioperative complications were identified and recorded.

Results

Complete data for review was available for 114 patients. Patients were subdivided based on BMI (group A 18.5–24.9, n = 43; group B 25–29.9, n = 49; group C ≥ 30, n = 22). There was no statistically significant difference in tumor burden, operative length, probability of unresectable disease, operative blood loss, or length of stay between groups. Rates of respiratory, gastrointestinal, infectious, renal, and hematologic complications were not statistically different, with the exception of deep vein thrombosis (A = 0, B = 13.5 %, C = 0; p = 0.026).

Conclusions

CRS-HIPEC can be safely performed in overweight and obese patients without significant increase in perioperative morbidity. Despite the limitations in physical examination and increase in visceral fat, they do not appear to present later than patients with normal BMI, nor do they have higher tumor burden.     

Impact of Body Mass Index on Perioperative Outcomes in Patients Undergoing Major Intra-abdominal Cancer Surgery

Background  Obesity is an increasingly common serious chronic health condition. We sought to determine the impact of body mass index (BMI) on perioperative outcomes in patients undergoing major intra-abdominal cancer surgery. Methods  A prospective, multi-institutional, risk-adjusted cohort study of patients undergoing major intra-abdominal cancer surgery was performed from the 14 university hospitals participating in the Patient Safety in Surgery Study of the National Surgical Quality Improvement Program (NSQIP). Demographic, clinical, and intraoperative variables and 30-day morbidity and mortality were prospectively collected in standardized fashion. Analysis of variance, Bonferroni multiple comparisons of means tests, and multivariable logistic regression analysis were performed. Results  We identified 2258 patients who underwent esophagectomy (n = 29), gastrectomy (n = 223), hepatectomy (n = 554), pancreatectomy (n = 699), or low anterior resection/proctectomy (n = 753). Patients were stratified by National Institutes of Health (NIH)-defined BMI obesity class, with 573 (25.4%) patients classified as obese (BMI > 30 kg/m²). There were no differences in mean work relative value units, total time of operation, or length of stay amongst the BMI classes. After adjusting for other risk factors, obesity was not a risk factor for death or major complications but was a risk factor for wound complications. The risk of postoperative death was greatest in underweight patients (odds ratio [OR] 5.24; 95% confidence interval [CI] 1.7–16.2). Conclusion  In patients undergoing major intra-abdominal cancer surgery, obesity is not a risk factor for postoperative mortality or major complications. Importantly, underweight patients have a fivefold increased risk of postoperative mortality, perhaps a consequence of their underlying nutritional status.     

Diabetes, Body Mass Index, and Outcomes in Hepatocellular Carcinoma Patients Undergoing Liver Transplantation

: For many cancers, features of the metabolic syndrome, such as diabetes and obesity, have been associated with both increased risk of cancer development and poor outcomes. METHODS: We examined a large retrospective cohort of 342 consecutive patients who underwent liver transplantation for hepatocellular carcinoma between January 1999 and July 2010 at our institution. We evaluated the relationship between diabetes, obesity, hepatocellular carcinoma (HCC) recurrence, and overall survival. RESULTS: We found that a body mass index (BMI) higher than 30 was an independent predictor of poor overall survival in a multivariable Cox model, approximately doubling the risk of death after transplantation. A BMI higher than 30 was also a predictor of recurrent HCC, although this was of borderline statistical significance (hazard ratio for recurrence, 1.9; 95% confidence interval, 0.9-4.1). We also found increased BMI to be an independent predictor of microvascular invasion within HCC tumors, lending a possible explanation to these results. Those with diabetes showed worsened overall survival compared with those without diabetes in univariate but not multivariable analysis, possibly related to longer wait times. CONCLUSIONS: Our findings suggest a relationship between higher BMI, tumor vascular invasion, increased recurrence, and worsened overall survival. These findings may help explain why those with high BMI have worse outcomes from their cancers. A better understanding of the role of obesity and diabetes in patients with cancer should help develop better predictors of outcome and improved treatment options for patients with HCC.