Examining the robustness of the obesity paradox in maintenance hemodialysis patients: a marginal structural model analysis

Investigating the causal association of generalized and abdominal obesity with microvascular complications in patients with type 2 diabetes: A community-based prospective study

AIM

The paradoxical protective association between overweight/obesity and diabetic microvascular complications (DMC), a phenomenon well-known as the obesity paradox, has been considered a non-causal association based on methodological influences. We aimed to investigate the association of generalized and abdominal obesity, as measured by body mass index (BMI) and waist circumference (WC), respectively, with DMC in patients with type 2 diabetes (T2D), using a causal inference approach.

MATERIALS AND METHODS

We enrolled 1436 patients with clinically diagnosed T2D but not DMC at baseline in a community-based prospective cohort in China between 2017 and 2019 and followed them annually until 2022 with new-onset DMC recorded. Marginal structural Cox models with inverse probability weighting were constructed to determine the causal association. Subgroup analyses were performed to identify potential effect modifiers.

RESULTS

We observed 360 incident DMC cases, including 109 cases of diabetic nephropathy (DN) and 277 cases of diabetic retinopathy (DR) during four follow-up visits. Multivariable-adjusted hazard ratios (95% confidence intervals) for overall DMC, DN and DR were 1.037 (1.005-1.071), 1.117 (1.062-1.175) and 1.018 (0.980-1.059) for 1 kg/m2 increase in BMI, and 1.005 (0.994-1.017), 1.034 (1.018-1.051) and 1.000 (0.987-1.014) for 1 cm increase in WC, respectively. Similar patterns were observed across the BMI and WC categories, while the positive association appeared to be more pronounced in women.

CONCLUSIONS

Generalized but not abdominal obesity was associated with an increased risk for the overall DMC, whereas both obesities were causally related to DN, albeit not DR, in T2D. Routine weight management should not be neglected in diabetes care, particularly in women.

Hypertension and Cardiovascular Risk Among Children with Chronic Kidney Disease

PURPOSE OF REVIEW

Cardiovascular disease is the most common cause of mortality across the lifespan of children with chronic kidney disease (CKD). Hypertension is a common and important contributor, but other factors such as obesity, dyslipidemia and mineral bone disease play a role. This narrative review focusses on studies published in the past five years that have investigated hypertension and cardiovascular risk among children with CKD.

RECENT FINDINGS

Cohort studies such as Chronic Kidney Disease in Children (CKiD) and Cardiovascular Comorbidity in Children with CKD (4C) have continued to develop our understanding of blood pressure (BP) phenotypes, and of progressive changes in the structure and function of the heart and blood vessels occurring in children with CKD. Metabolic risk factors, such as dyslipidemia, may represent an under-recognized component of care. Trial data are less common than observational evidence, but support lifestyle interventions currently used, mainly the low sodium dietary approaches to stop hypertension (DASH) diet. The findings of the recently reported Hypertension Optimal Treatment in Children with Chronic Kidney Disease trial (HOT-KID) are described in relation to the use of office BP treatment targets. Cardiovascular health is critical to the long-term outcomes of children with CKD. Recognizing and treating hypertension remains a critical component to improving outcomes, along with measures to improve concurrent cardiovascular risk factors. Some cardiovascular changes may not be reversible with transplantation and further research is needed for children at all stages of CKD.

Long-term Effects of Kidney Transplantation Compared With Dialysis on Intima-media Thickness in Children-Results From the 4C-T Study

BACKGROUND

Children requiring kidney replacement therapy experience high burden of cardiovascular (CV) disease leading to increased mortality. Intima-media thickness (IMT) indicating atherosclerosis is a validated surrogate marker for future CV events.

METHODS

We investigated the effect of different treatment modalities (dialysis, preemptive kidney transplantation (KTx), late KTx after dialysis) on IMT by multivariable linear mixed-effect modeling. Patients were enrolled in a prospective cohort study.

RESULTS

A total of 261 analyzed children had a mean follow-up of 3 y. Children after preemptive and late KTx had lower levels of IMT when compared with dialysis. Using an interaction term, a significant progression of IMT over time was seen during dialysis (β = 0.0053 mm/y, P   =  0.004). IMT before the start of therapy was the most influential determinant in all models. Low IMT was associated with maintenance steroid treatment after preemptive KTx. High IMT on dialysis was associated with higher systolic blood pressure, lower body mass index, lower serum albumin, and lower bicarbonate.

CONCLUSIONS

IMT remained rather stable in children several years after KTx. In contrast, children on dialysis had higher IMT values, which increased over time. In these children, blood pressure control, calorie and protein intake, and acid-base homeostasis seem important. Taken together, children might profit from early transplantation to limit accumulation of CV risk.

Omega-3 supplementation effects on cardiovascular risk and inflammatory profile in chronic kidney disease patients in hemodialysis treatment: An intervention study

BACKGROUND AND AIMS

Chronic Kidney Disease (CKD) is characterized by slow, progressive, and irreversible kidney function loss and the disease itself and hemodialysis treatment can predispose an inflammatory state that increased cardiovascular complications, being one of major mortality causes in kidney patients. The study purpose was to evaluate nutritional profile and impacts of w-3 fatty acid supplementation on inflammatory parameters and cardiovascular events risk in patients with CKD undergoing hemodialysis treatment.

METHODS

Non-randomized clinical trial, patients with CKD were randomly grouped into a control (n = 29) and supplemented (n = 30) group. Supplemented group patients were instructed to consume two w-3 capsules a day (2g/day) for 8 weeks for further analysis of pre- and post-supplementation C-reactive protein (CRP) and other blood parameters. To nutritional status assessment, anthropometric and bioelectrical impedance data were measured, carried out close to supplementation start.

RESULTS

59 patients were evaluated, 49.1% (n = 29) were overweight and 70.7% (n = 41) had high percentage of body fat. Comparing control versus supplemented groups after supplementation serum CRP levels have reduced, no differences were observed (p = 0.716) nevertheless there was reduction in cardiovascular events risk according to C-reactive protein classification (p = 0.004). Ferritin levels have improved in all groups. Changes in the levels of other biochemical markers hemoglobin, hematocrit, urea, creatinine, and Kt/v have happened. However, group that received w-3 showed an improvement in serum albumin levels (p = 0.014), in addition to demonstrating greater adequacy classification of albumin after supplementation (p = 0.022).

CONCLUSION

Omega-3 supplementation have caused an improvement in albumin plasma levels suitableness in Chronic Kidney Disease patients, however, it did not demonstrate statistical effects to reducing CRP levels, although this helped to reduce cardiovascular risk.

Patient and Health Care Professional Perspectives on Addressing Obesity in ESKD

RATIONALE & OBJECTIVE

Obesity is common among patients with end-stage kidney disease (ESKD) and is a pervasive barrier to kidney transplantation. Patient perspectives about barriers to weight loss and patient and health care professionals' viewpoints about optimal obesity management in ESKD are needed.

STUDY DESIGN

Qualitative study using a descriptive phenomenological approach to understand ESKD patients' lived experiences with obesity and weight loss and patients' and health professionals' perceptions about optimal obesity care for ESKD patients.

SETTING & PARTICIPANTS

Between October 2020 and December 2021, we conducted 90-minute semistructured interviews with 40 ESKD patients with obesity (body mass index [BMI] ≥30kg/m2) and 60-minute interviews with 20 ESKD health care professionals.

ANALYTICAL APPROACH

Deductive and inductive thematic analysis of interviews.

RESULTS

Among patients with ESKD, the median age was 55 (IQR, 46-63) years, median BMI was 39.5 (IQR, 35.3-41.6) kg/m2, and median dialysis vintage was 5 (IQR, 3-8) years; 58% were female, and 46% were non-Hispanic White. Among health care professionals, 50% were renal dietitians, 20% were nephrologists, and the remainder were transplant professionals (surgeons, nephrologists, and dietitians). ESKD patients described unique weight loss challenges, including (1) conflicting tenets of "kidney-friendly" versus popular diets, (2) fatigue due to dialysis that affects dietary choices, and (3) perceived pressure and unrealistic expectations from health professionals to lose weight for kidney transplantation. Professionals and patients described a lack of transparent and honest communication about obesity and unclear roles and responsibilities for obesity counseling.

LIMITATIONS

Lack of caregiver perspectives and potential lack of transferability to overall dialysis population given overrepresentation of patients with severe obesity and previous weight loss surgery.

CONCLUSIONS

Obesity interventions for ESKD patients should be tailored to meet the unique challenges reported by patients with ESKD. Clarifying ESKD health professionals' roles and responsibilities for obesity care would help to ensure that patients have consistent and effective support to manage obesity.

PLAIN-LANGUAGE SUMMARY

Adults with coexisting obesity and end-stage kidney disease (ESKD) are often required to lose weight for kidney transplantation. Yet there is little knowledge about barriers to healthy weight loss in this population. In this study, we conducted interviews with 40 ESKD patients with coexisting obesity and 20 ESKD health care professionals to learn about opportunities to improve obesity-related health care in ESKD. Patients reported that fatigue and dialysis affected dietary choices, and fluid and food restrictions hampered weight loss. Professionals described a lack of training, comfort, and time to address obesity. Patients and professionals reported a lack of open communication about obesity management. Improving obesity-related education and clinical communication should be prioritized to improve care for patients with ESKD and obesity.

Obesity Weight Loss Phenotypes in CKD: Findings From the Chronic Renal Insufficiency Cohort Study

Introduction

Although people with chronic kidney disease (CKD) and obesity have important motivations to lose weight, weight loss is also associated with health risks. We examined whether patterns of change in systolic blood pressure (SBP), serum albumin level, and fat-free mass (FFM) can help to differentiate between healthy and high-risk weight loss in this population.

Methods

Using data from the Chronic Renal Insufficiency Cohort Study (CRIC), we estimated a joint multivariate latent class model with 6 classes to identify distinct trajectories of body mass index (BMI), albumin, and SBP among participants with obesity (BMI ≥30 kg/m2 at baseline), accounting for informative missingness from death. In a secondary analysis, we fit a 6-class model with BMI and FFM.

Results

Among 2831 participants (median baseline BMI 35.6, interquartile range [IQR] 32.4-40.0 kg/m2), median follow-up was 6.8 (IQR 4.8-12.9) years, median age was 61 (IQR 54-67) years, 53% were male, 50% were non-Hispanic Black, and 82% were trying to control or lose weight at baseline. Latent classes were associated with mortality risk (5-year cumulative incidence of mortality 6.8% and 1.5% in class 6 and 3, respectively). Class 6 had the highest mortality rate and was characterized by early, steep BMI loss, early serum albumin decline, and late SBP increase. In the secondary analysis, a class characterized by steep BMI and FFM loss was associated with the highest death risk.

Conclusions

Among adults with CKD and obesity, BMI loss with concomitant serum albumin or FFM loss was associated with a high risk of death.

Diagnosis, Prevalence and Significance of Obesity in a Cohort of CKD Patients

BACKGROUND

data regarding the association between obesity and morbidity/mortality in patients with chronic kidney disease (CKD) are uncertain and sometimes contradictory. The aims of our study were to determine the associations among different measures of obesity and adiposity, and the risk of all-cause mortality or dialysis entry in stage 3-5 CKD patients.

MATERIALS

this observational cohort study included 178 CKD patients followed for a median of 71 months. Biochemistry, anthropometric measures such as body mass index (BMI), waist-to-hip ratio, mid-arm muscle circumference (MAMC) and body composition by bioimpedance analysis were evaluated.

RESULTS

we found a weak agreement between BMI and other measures of adiposity. In multivariable regression analysis, all measures of obesity such as BMI, waist circumference and waist-to-height ratio were not associated with dialysis entry and/or mortality. Instead, MAMC was associated with dialysis entry HR 0.82 [95% CI: 0.75-0.89] and high FM% with mortality HR 2.08 [95% CI: 1.04-4.18].

CONCLUSIONS

in our CKD population, lower MAMC was predictive of dialysis commencing, while a higher percentage of fatty mass was a predictor of mortality. Instead, obesity, as defined by BMI, is not associated with dialysis commencing or all-cause mortality.

Impact of body mass index on in-hospital mortality in older patients hospitalized for bacterial pneumonia with non-dialysis-dependent chronic kidney disease

BACKGROUND

Low body mass index (BMI) in older individuals with decreased kidney function is important because of its association with poor prognosis and frailty. Herein, we aimed to clarify the association between BMI and in-hospital mortality among older patients with non-dialysis-dependent chronic kidney disease (CKD) stratified by kidney function.

METHODS

Using data from the Medical Vision Database, this multicentre cohort study included people aged ≥ 60 years with an estimated glomerular filtration rate of < 60 ml/min/1.73 m² but without dialysis dependency, hospitalised for bacterial pneumonia during 2014-2019. We compared the risk of in-hospital death between patients with BMI categories based on the quartiles (low, medium-low, medium-high, and high) setting medium-high BMI as a reference. We further assessed the association with BMI using a cubic spline, setting BMI as a nonlinear continuous variable and a BMI of 22 kg/m² as a reference. We also evaluated the association between BMI and kidney function using a generalised additive model adjusted for interaction terms between nonlinear continuous BMI and kidney function.

RESULTS

We obtained data for 3,952 patients, with 350 (8.9%) in-hospital deaths. When compared with medium-high BMI, low BMI was associated with an increased risk of death and longer hospital stay, whereas the other two categories were comparable. Models using a cubic spline showing an association between BMI and in-hospital death showed an L-shaped curve; BMI < 22.0 kg/m² was associated with an increased risk for mortality, and at a BMI of 18.5 kg/m², the odds ratio was 1.43 with a 95% confidence interval of 1.26-1.61 when compared with a BMI of 22.0 kg/m². Analysis of the interactive effects of kidney function using the generalised additive model showed that a protective association of high BMI tapered along with decreased kidney function.

CONCLUSIONS

This cohort study suggests not only that lower BMI and low kidney function are associated with in-hospital mortality independently but also that the protective effects of high BMI weaken as kidney function decreases via the analysis of the interaction terms. This study highlights the necessity for the prevention of underweight and demonstrates the interaction between BMI and kidney function in older patients with non-dialysis-dependent CKD.

Trends, Social Context, and Transplant Implications of Obesity Among Incident Dialysis Patients in the United States

BACKGROUND

Kidney transplant programs have variable thresholds to accept obese candidates. This study aimed to examine trends and the social context of obesity among United States dialysis patients and implications for kidney transplant access.

METHODS

We performed a retrospective cohort study of 1 084 816 adults who initiated dialysis between January 2007 and December 2016 using the United States Renal Data System data. We estimated national body mass index (BMI) trends and 1-y cumulative incidence of waitlisting and death without waitlisting by BMI category (<18.5 kg/m 2 , ≥18.5 and <25 kg/m 2 [normal weight], ≥25 and <30 kg/m 2 [overweight], ≥30 and <35 kg/m 2 [class 1 obesity], ≥35 and <40 kg/m 2 [class 2 obesity], and ≥40 kg/m 2 [class 3 obesity]). We then used Fine-Gray subdistribution hazard regression models to examine associations between BMI category and 1-y waitlisting with death as a competing risk and tested for effect modification by End Stage Renal Disease (ESRD) network, patient characteristics, and neighborhood social deprivation index.

RESULTS

The median age was 65 (interquartile range 54-75) y, 43% were female, and 27% were non-Hispanic Black. From 2007 to 2016, the adjusted prevalence of class 1 obesity or higher increased from 31.9% to 38.2%. Class 2 and 3 obesity but not class 1 obesity were associated with lower waitlisting rates relative to normal BMI, especially for younger individuals, women, those of Asian race, or those living in less disadvantaged neighborhoods ( pinteraction < 0.001 for all).

CONCLUSIONS

Obesity prevalence is rising among US incident dialysis patients. Relative to normal BMI, waitlisting rates with class 2 and 3 obesity were lower and varied substantially by region, patient characteristics, and socioeconomic context.

Development and Validation of a Nomogram Model for Predicting the Risk of Readmission in Patients with Heart Failure with Reduced Ejection Fraction within 1 Year

The high incidence of readmission for patients with reduced ejection fraction heart failure (HFrEF) can seriously affect the prognosis. In this study, we aimed to build a simple predictive model to predict the risk of heart failure (HF) readmission in patients with HFrEF within one year of discharge from the hospital. This retrospective study enrolled patients with HFrEF evaluated in the Heart Failure Center of the Affiliated Hospital of Xuzhou Medical University from January 2018 to December 2020. The patients were allocated into the readmission or nonreadmission group, according to whether HF readmission occurred within 1 year of hospital discharge. Subsequently, all patients were randomly divided into training and validation sets in a 7 : 3 ratio. A nomogram was established according to the results of univariate and multivariate logistic regression analysis. Finally, the area under the receiver operating characteristic curve (AUC-ROC), calibration plot, and decision curve analysis (DCA) were used to validate the nomogram. Independent risk factors for HF readmission of patients with HFrEF within 1 year of hospital discharge were as follows: age, body mass index, systolic blood pressure, diabetes mellitus, left ventricular ejection fraction, and angiotensin receptor-neprilysin inhibitors. The AUC-ROC of the training and validation sets were 0.833 (95% confidence interval (CI): 0.793-0.866) and 0.794 (95% CI: 0.727-0.852), respectively, which have an excellent distinguishing ability. The predicted and observed values of the calibration curve also showed good consistency. DCA also confirmed that the nomogram had good clinical value. In conclusion, we constructed an accurate and straightforward nomogram model for predicting the 1-year HF readmission risk in patients with HFrEF. This nomogram can guide early clinical intervention and improve patient prognosis.

Cohort Study and Bias Analysis of the Obesity Paradox Across Stages of Chronic Kidney Disease

OBJECTIVE

In advanced chronic kidney disease (CKD), patients with obesity often have better outcomes than patients without obesity, often called the 'obesity paradox'. Yet, in CKD, the prevalence of inflammation increases as CKD progresses. Although a potential confounder, inflammation may be left unaccounted in obesity-mortality studies. We examined the associations of body mass index (BMI) with all-cause and cause-specific mortality across CKD stages, with consideration for uncontrolled confounding due to unmeasured inflammation.

METHODS

We investigated 2,703,512 patients with BMI data between 2004 and 2006. We used Cox models to examine the associations of BMI with all-cause, cardiovascular, and cancer mortality, (ref: BMI 25-<30 kg/m2), adjusted for clinical characteristics and stratified by CKD stages. To address uncontrolled confounding, we performed bias analysis using a weighted probabilistic model of inflammation given the observed data applied to weighted Cox models.

RESULTS

The cohort included 5% females and 14% African Americans. In adjusted analyses, the associations of the BMI with all-cause and cardiovascular mortality showed a reverse J-shape, where a higher BMI (>40 kg/m2) was associated with a higher risk. Conversely, a lower mortality risk was observed with a BMI 30-<35 kg/m2 across all CKD stages and for BMI >40 kg/m2 in CKD stage 4/5. Cancer mortality analyses showed an inverse relationship. Bias analysis for uncontrolled confounding suggested that independent of inflammation, the obesity paradox was present.

CONCLUSION

We observed the presence of the obesity paradox in this study. This association was consistent in advanced CKD and in our bias analysis, suggesting that inflammation may not fully explain the observed BMI-mortality associations including in patients with CKD.

Longitudinal causal effect of modified creatinine index on all-cause mortality in patients with end-stage renal disease: Accounting for time-varying confounders using G-estimation

Background

Standard regression modeling may cause biased effect estimates in the presence of time-varying confounders affected by prior exposure. This study aimed to quantify the relationship between declining in modified creatinine index (MCI), as a surrogate marker of lean body mass, and mortality among end stage renal disease (ESRD) patients using G-estimation accounting appropriately for time-varying confounders.

Methods

A retrospective cohort of all registered ESRD patients (n = 553) was constructed over 8 years from 2011 to 2019, from 3 hemodialysis centers at Kerman, southeast of Iran. According to changes in MCI, patients were dichotomized to either the decline group or no-decline group. Subsequently the effect of interest was estimated using G-estimation and compared with accelerated failure time (AFT) Weibull models using two modelling strategies.

Results

Standard models demonstrated survival time ratios of 0.91 (95% confidence interval [95% CI]: 0.64 to 1.28) and 0.84 (95% CI: 0.58 to 1.23) in patients in the decline MCI group compared to those in no-decline MCI group. This effect was demonstrated to be 0.57 (-95% CI: 0.21 to 0.81) using G-estimation.

Conclusion

Declining in MCI increases mortality in patients with ESRD using G-estimation, while the AFT standard models yield biased effect estimate toward the null.

Impact of Extremes of Body Mass Index (BMI) in End-Stage Renal Disease (ESRD) Patients

The principal objective of this systematic review is to determine the prognosis of end-stage renal disease (ESRD) patients on maintenance hemodialysis with high body mass index (BMI) and study the potential mechanisms behind it. PubMed and Google Scholar electronic databases covering the period of the last 30 years 1992 to 2022 are searched thoroughly and a total of 11 articles were finally selected for the study. Reference lists of included papers are also searched. Each paper was examined by two independent evaluators who also extracted data from full papers. The quality of the selected studies was assessed by different quality assessment tools and only moderate- to high-quality papers are included.

In this systematic review, we studied different mechanisms explaining the obesity paradox in patients on maintenance hemodialysis, i.e., hemodynamic stability, the concentration of TNF-α receptors, neurohumoral response, role of inflammation, blood pressure, etc. also, the effect of age, gender, duration of treatment, acetyl-ghrelin on obesity paradox have been considered in our paper. This systematic review demonstrates the evidence of an inverse relationship between BMI and all-cause mortality in ESRD patients on maintenance hemodialysis.

Quality indicators in hemodialysis: A 5-year experience of national campaigns in France

BACKGROUND

End stage kidney disease (ESKD) is associated with increased morbidity and mortality. Hemodialysis (HD) is the main technique used for kidney replacement therapy. Dialyzed patients are expected to live less than one half as long as their counterparts without ESKD. Improving quality of care may help to improve mortality in this population.

METHODS

The French National Authority for Health has carried out three consecutive national campaigns over 5 years for the assessment of quality indicators (QCI) during HD. QCI included anemia management, iron status evaluation, nutritional status assessment, and annual transplantation access.

RESULTS

From 2013 to 2017, 227 health facilities participated, and 33,319 files were analyzed. Median age was 72 years old (IQR_25-75  = 61-81), and 58.25% of patients were men. Median time in HD was 39.4 months (IQR_25-75  = 20.7-72.7). Most of the patients underwent in-center HD (85.41%). Overweight and obese patients accounted, respectively, for 28.39% and 21.32%, and malnutrition was present in 38.61%. A contra-indication for renal transplantation was found in 68.3% of patients. All QCI improved over 5 years.

CONCLUSION

Developing QCI based on guidelines is crucial to assure appropriate care of HD patients. Repeating campaigns over 5 years in France improves the quality of care among physicians.

Characteristics and predictors of mortality on haemodialysis in Brazil: a cohort of 5,081 incident patients

Background

Although Brazil has one of the largest populations on haemodialysis (HD) in the world, data regarding patients’ characteristics and the variables associated with risk of death are scanty.

Methods

This is a retrospective analysis of all adult patients who initiated on maintenance HD at 23 dialysis centres in Brazil between 2012 and 2017. Patients were censored after 60 months of follow-up or at the end of 2019.

Results

A total of 5,081 patients were included in the analysis. The median age was 59 years, 59.4% were men, 37.5% had diabetes as the cause of kidney failure. Almost 70% had a central venous catheter (CVC) as the initial vascular access, about 60% started dialysis in the hospital, and fluid overload (FO) by bioimpedance assessment was seen in 45% of patients. The 60-month survival rate was 51.4%. In the Cox regression analysis, being older (P<0.0001), starting dialysis in the hospital (P=0.016), having diabetes as the cause of kidney failure (P=0.001), high alkaline phosphatase (P=0.005), CVC as first vascular access (P=0.023), and FO (P<0.0001) were associated with higher death risk, whereas higher body mass index (P=0.015), haemoglobin (P=0.004), transferrin saturation (P=0.002), and serum albumin (P<0.0001) were associated with better survival. The same variables, except initial CVC use (P=0.14), were associated with death risk in an analysis of subdistribution proportional hazards ratio including the competing outcomes.

Conclusions

The present study gives an overview of a large HD population in a developing country and identifies the main predictors of mortality, including some potentially modifiable ones, such as unplanned initiation of dialysis in the hospital and fluid overload.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02705-x.

Obesity Management in Kidney Transplant Candidates: Current Paradigms and Gaps in Knowledge

In this review, we discuss the increasing prevalence of obesity among people with chronic and end-stage kidney disease (ESKD) and implications for kidney transplant (KT) candidate selection and management. Although people with obesity and ESKD receive survival and quality-of-life benefits from KT, most KT programs maintain strict body mass index (BMI) cutoffs to determine transplant eligibility. However, BMI does not distinguish between visceral adiposity, which confers higher cardiovascular risks and risks of perioperative and adverse posttransplant outcomes, and muscle mass, which is protective in ESKD. Furthermore, requirements for patients with obesity to lose weight before KT should be balanced with the findings of numerous studies that show weight loss is a risk factor for death among patients with ESKD, independent of starting BMI. Data suggest that KT is associated with survival benefits relative to remaining on dialysis for candidates with obesity although recipients without obesity have higher delayed graft function rates and longer transplant hospitalization durations. Research is needed to determine the optimal body composition metrics for KT candidacy assessments and risk stratification. In addition, ESKD-specific obesity management guidelines are needed that will address the neurologic, behavioral, socioeconomic, and physical underpinnings of this increasingly common disease.

Dialysis of the Obese Patient: Meeting Needs for a Growing Epidemic

Increasing population obesity and associated metabolic consequences has led to increased number of obese patients with chronic kidney disease and end-stage renal disease. While obesity is associated with increased cardiovascular morbidity and mortality, obese dialysis patients present a seeming paradox for survival benefit, given other acute intervening illnesses for those on dialysis with loss of lean body mass overtime. Challenges remain in providing adequate renal replacement options and therapy for this growing segment of obese patients on dialysis which are discussed in this article.

The Prognostic Significance of Body Mass Index and Metabolic Parameter Variabilities in Predialysis CKD: A Nationwide Observational Cohort Study

BACKGROUND

The association between variabilities in body mass index (BMI) or metabolic parameters and prognosis of patients with CKD has rarely been studied.

METHODS

In this retrospective observational study on the basis of South Korea's national health screening database, we identified individuals who received ≥3 health screenings, including those with persistent predialysis CKD (eGFR <60 ml/min per 1.73 m² or dipstick albuminuria ≥1). The study exposure was variability in BMI or metabolic parameters until baseline assessment, calculated as the variation independent of the mean and stratified into quartiles (with Q4 the highest quartile and Q1 the lowest). We used Cox regression adjusted for various clinical characteristics to analyze risks of all-cause mortality and incident myocardial infarction, stroke, and KRT.

RESULTS

The study included 84,636 patients with predialysis CKD. Comparing Q4 versus Q1, higher BMI variability was significantly associated with higher risks of all-cause mortality (hazard ratio [HR], 1.66; 95% confidence interval [95% CI], 1.53 to 1.81), P [for trend] <0.001), KRT (HR, 1.20; 95% CI, 1.09 to 1.33; P<0.001), myocardial infarction (HR, 1.19; 95% CI, 1.05 to 1.36, P=0.003), and stroke (HR, 1.19; 95% CI, 1.07 to 1.33, P=0.01). The results were similar in the subgroups divided according to positive or negative trends in BMI during the exposure assessment period. Variabilities in certain metabolic syndrome components (e.g., fasting blood glucose) also were significantly associated with prognosis of patients with predialysis CKD. Those with a higher number of metabolic syndrome components with high variability had a worse prognosis.

CONCLUSIONS

Higher variabilities in BMI and certain metabolic syndrome components are significantly associated with a worse prognosis in patients with predialysis CKD.

A Cross-Sectional Study for Prevalence and Association of Risk Factors of Chronic Kidney Disease Among People With Type 2 Diabetes in the Indian Setting

INTRODUCTION

Current evidence demonstrates that people with type 2 diabetes (T2D) are at a higher risk of developing chronic kidney disease (CKD) with greater morbidity and mortality. We, therefore, aimed to document and categorize demographic, anthropometric, and physiological risk factors of CKD in people with T2D in India. Additionally, we also attempted to evaluate the magnitude of each risk factor, namely age, duration of diabetes, HbA1c, and body mass index (BMI) in its etiology.

METHODS

This observational, single-center, and cross-sectional study was performed at a diabetes care center in Lucknow, India. Out of a total of 504 eligible patients, we could get the required data from 435 patients. The following data were collected: demographic data, estimated glomerular filtration rate (eGFR), serum creatinine, urinary albumin creatinine ratio (UACR), and HbA1c levels. Appropriate statistical tests were applied.

RESULT

The 435 eligible people with diabetes had a mean age (SD) of 51 (±10.52) years; female 48.02%, duration of diabetes 7 (±5.4) years; HbA1c 8.6 (±2.3)% and eGFR values 80.2 (±26.6) mL/min/1.73m2 at the time of presentation. The eGFR values correlated negatively with age and duration of diabetes, and positively with increasing BMI. The Spearman correlation coefficient showed that clinical parameters such as age, duration of diabetes, and BMI have a weak, but statistically significant correlation with eGFR while eGFR did not correlate with HbA1c level in the study. Further, we did not find a correlation between eGFR and UACR.

CONCLUSION

In people with T2D, age and duration of diabetes are important risk factors for the development of CKD based on the eGFR. Hence, even in the absence of high UACR values, a low eGFR should prompt periodic monitoring to reduce the risk of progression of CKD, especially, in older people with long-standing T2D. Our study did not find HbA1c as a suitable tool to assess the CKD progression risk, but historical glycaemic control over longer periods revealed by sequential values of HbA1c over the duration of disease may correlate with the progression of CKD.

Association analysis of body composition with survival among prevalent peritoneal dialysis patients

PURPOSE

Progressive decline in lean mass and gain of fat mass are common in patients treated with peritoneal dialysis (PD). It is unclear whether body composition or its longitudinal changes contribute to increased mortality among prevalent PD patients.

METHODS

This was a retrospective cohort study. Body composition was assessed using bioelectrical impedance spectroscopy (BIS). Lean and fat tissue indices were derived from lean and fat mass indexed to height-squared, respectively. The patient's baseline BIS results were used to explore its mortality risk prediction for the entire cohort. Among patients with subsequent BIS measurements, changes of lean and fat mass over time were also examined with survival outcomes.

RESULTS

Among all participants (n = 555, PD vintage 38 months), higher baseline lean tissue index was associated with lower mortality after adjusting for fat tissue index and confounders (HR 0.90; 95% CI 0.84-0.97, p = 0.01). However, this association was no longer significance after the final adjustment with serum albumin level (p = 0.06). A total of 136 patients had repeated BIS data. After the interval of 10.1 months during two consecutive BIS measurements, there was a strong inverse correlation between the percentage changes of lean and fat tissue indices (r = - 0.73, p < 0.001). The longitudinal changes in lean mass, either high or low categories, were not significantly associated with all-cause mortality. In contrast, patients who were classified as having low values of fat tissue index (below median) from baseline to the next BIS measurements had a lower odds of death in the univariable (HR 0.32; 95% CI 0.12-0.84, p = 0.02) but not in the adjusted models.

CONCLUSION

Among prevalent PD patients, higher baseline lean mass was independently associated with better survival. However, the longitudinal changes in lean mass were not significantly associated with mortality. In contrast, the maintenance of low fat status over time appeared to be associated with a lower likelihood of death among PD population.

Significance of Adipose Tissue Maintenance in Patients Undergoing Hemodialysis

In the general population, obesity is known to be associated with adverse outcomes, including mortality. In contrast, high body mass index (BMI) may provide a survival advantage for hemodialysis patients, which is known as the obesity paradox. Although BMI is the most commonly used measure for the assessment of obesity, it does not distinguish between fat and lean mass. Fat mass is considered to serve as an energy reserve against a catabolic condition, while the capacity to survive starvation is also thought to be dependent on its amount. Thus, fat mass is used as a nutritional marker. For example, improvement of nutritional status by nutritional intervention or initiation of hemodialysis is associated with an increase in fat mass. Several studies have shown that higher levels of fat mass were associated with better survival in hemodialysis patients. Based on body distribution, fat mass is classified into subcutaneous and visceral fat. Visceral fat is metabolically more active and associated with metabolic abnormalities and inflammation, and it is thus considered to be a risk factor for cardiovascular disease and mortality. On the other hand, subcutaneous fat has not been consistently linked to adverse phenomena and may reflect nutritional status as a type of energy storage. Visceral and subcutaneous adipose tissues have different metabolic and inflammatory characteristics and may have opposing influences on various outcomes, including mortality. Results showing an association between increased subcutaneous fat and better survival, along with other conditions, such as cancer or cirrhosis, in hemodialysis patients have been reported. This evidence suggests that fat mass distribution (i.e., visceral fat and subcutaneous fat) plays a more important role for these beneficial effects in hemodialysis patients.

Recipient Obesity and Kidney Transplant Outcomes: A Mate-Kidney Analysis

RATIONALE & OBJECTIVE

The impact of extreme recipient obesity on long-term kidney transplant outcomes has been controversial. This study sought to evaluate the association of various levels of recipient obesity on kidney transplantation outcomes by comparing mate-kidney recipient pairs to address possible confounding effects of donor characteristics on posttransplant outcomes.

STUDY DESIGN

Nationwide observational cohort study using mate-kidney models.

SETTING & PARTICIPANTS

In analysis based on the Organ Procurement and Transplant Network/United Network of Organ Sharing database, 44,560 adult recipients of first-time deceased-donor kidney transplants from 2001 through 2016 were paired by donor.

PREDICTORS

Recipient body mass index (BMI) categorized as 18-25 (n = 12,446), >25-30 (n = 15,477), >30-35 (n = 11,144; obese), and >35 (n = 5,493; extreme obesity) kg/m².

OUTCOMES

Outcomes included patient survival, graft survival, death-censored graft survival, delayed graft function (DGF), and hospital length of stay.

ANALYTICAL APPROACH

Conditional logistic regression and stratified proportional hazards models were used to compare outcomes as odds ratios and hazard ratios (HRs), adjusted for recipient and transplant factors, using recipients with a BMI >35 kg/m² as a reference.

RESULTS

At a median follow-up of 3.9 years, adjusted odds ratios for DGF were 0.42 (95% CI, 0.36-0.48), 0.55 (95% CI, 0.48-0.62), and 0.73 (95% CI, 0.64-0.83) for BMI 18-25, >25-30, and >30-35 kg/m², respectively (P < 0.001 for all). Death-censored graft failure was less frequent for BMI ≤25 and >25-30 kg/m² (HRs of 0.66 [95% CI, 0.59-0.74] and 0.79 [95% CI, 0.70-0.88], respectively; P < 0.001 for both), but not for BMI >30-35 kg/m² (HR, 0.91 [95% CI, 0.81-1.02]; P = 0.09). Length of stay and patient survival did not differ by recipient BMI.

LIMITATIONS

Observational study with limited detail regarding potential confounders.

CONCLUSIONS

Despite an increased risk of DGF likely unrelated to donor organ quality, long-term transplant outcomes among recipients with a BMI >35 kg/m² are similar to those among recipients with a BMI >30-35 kg/m², supporting a flexible approach to kidney transplantation candidacy in candidates with extreme obesity.

KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update

The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for nutrition in kidney diseases since 1999. Since the publication of the first KDOQI nutrition guideline, there has been a great accumulation of new evidence regarding the management of nutritional aspects of kidney disease and sophistication in the guidelines process. The 2020 update to the KDOQI Clinical Practice Guideline for Nutrition in CKD was developed as a joint effort with the Academy of Nutrition and Dietetics (Academy). It provides comprehensive up-to-date information on the understanding and care of patients with chronic kidney disease (CKD), especially in terms of their metabolic and nutritional milieu for the practicing clinician and allied health care workers. The guideline was expanded to include not only patients with end-stage kidney disease or advanced CKD, but also patients with stages 1-5 CKD who are not receiving dialysis and patients with a functional kidney transplant. The updated guideline statements focus on 6 primary areas: nutritional assessment, medical nutrition therapy (MNT), dietary protein and energy intake, nutritional supplementation, micronutrients, and electrolytes. The guidelines primarily cover dietary management rather than all possible nutritional interventions. The evidence data and guideline statements were evaluated using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.

Association of Body Mass Index and Waist Circumference with All-Cause Mortality in Hemodialysis Patients

In this study based on a large nationally representative sample of Korean adults, we investigated the potential associations of the body mass index (BMI) and waist circumference (WC) with mortality in patients undergoing hemodialysis. We obtained the data of 18,699 participants >20 years of age who were followed up with for 4 years and for whom BMI and WC information were available, using a nationally representative dataset from the Korean National Health Insurance System. Patients were stratified into five levels by their baseline BMI and into six levels by their WC (5-cm increments). A total of 4975 deaths occurred during a median follow-up period of 48.2 months. Participants with a higher BMI had a lower mortality rate than those with a lower BMI. In a fully adjusted Cox regression analysis, being overweight and obese was associated with a significantly lower relative risk of all-cause mortality relative to the reference group. Conversely, the mortality rate was higher among participants with a high WC than among those with a low WC. Participants with the highest WC had a higher risk of mortality, while those with the lowest WC level had a significantly lower risk of mortality. In conclusion, all-cause mortality was positively associated with WC, a measure of abdominal obesity, and inversely associated with BMI, a measure of body volume, in patients undergoing hemodialysis.

Associations of Systolic Blood Pressure With Incident CKD G3-G5: A Cohort Study of South Korean Adults

RATIONALE & OBJECTIVE

Clinical practice guidelines recommend a target blood pressure (BP)<130/80 mm Hg to reduce cardiovascular risk. However, the optimal BP to prevent chronic kidney disease (CKD) is unknown.

STUDY DESIGN

Population-based retrospective cohort study.

SETTING & PARTICIPANTS

10.5 million adults who participated in the National Health Insurance Service National Health Checkup Program in South Korea between 2009 and 2015 and had an estimated glomerular filtration rate (GFR) ≥ 60 mL/min/1.73 m² at the beginning of follow-up.

PREDICTORS

Baseline and time-updated systolic BP (SBP) as a continuous variable and categorized as<110, 110 to 119, 120 to 129, 130 to 139, or≥140 mm Hg.

OUTCOME

Incident CKD GFR categories 3 to 5 (CKD G3-G5), defined as de novo development of estimated GFR<60 mL/min/1.73 m² for at least 2 consecutive assessments confirmed at least 90 days apart.

ANALYTICAL APPROACH

Cox proportional hazards regression for baseline BP and marginal structural analysis for time-updated BP.

RESULTS

During 49,169,311 person-years of follow-up, incident CKD G3-G5 developed in 172,423 (1.64%) individuals with a crude event rate of 3.51 (95% CI, 3.49-3.52) per 1,000 person-years. Compared to a baseline SBP of 120 to 129 mm Hg, HRs for incident CKD G3-G5 for the<110, 110 to 119, 130 to 139, and≥140 mm Hg categories were 0.84 (95% CI, 0.82-0.85), 0.92 (95% CI, 0.91-0.94), 1.11 (95% CI, 1.09-1.12), and 1.30 (95% CI, 1.28-1.31), respectively. For time-updated SBPs, corresponding HRs were 0.57 (95% CI, 0.56-0.59), 0.79 (95% CI, 0.78-0.80), 1.58 (95% CI, 1.55-1.60), and 2.49 (95% CI, 2.45-2.53), respectively. Treated as a continuous exposure, each 10-mm Hg higher SBP was associated with 35% higher risk for incident CKD G3-G5 (95% CI, 1.35-1.36).

LIMITATIONS

Use of International Classification of Diseases codes to assess comorbid condition burden; residual confounding, and potential selection bias cannot be excluded.

CONCLUSIONS

In this large national cohort study, higher SBPs were associated with higher risk for incident CKD G3-G5. These findings support evaluation of SBP-lowering strategies to reduce the development of CKD.

Impact of obesity on dialysis and transplant and its management

Obesity is increasing to unprecedented levels, including in the end-stage kidney disease population, where upwards of 60% of kidney transplant patients are overweight or obese. Obesity poses additional challenges to the care of the dialysis patient, including difficulties in creating vascular access and inserting Tenckhoff catheters, higher rates of catheter malfunction and peritonitis, the need for longer and/or more frequent dialysis (or peritoneal dialysis [PD] exchanges) to achieve adequate clearance, increased metabolic complications particularly with PD, and obesity is a barrier to kidney transplantation. In this article, we review special considerations in performing PD, hemodialysis and transplant in the obese patient, as well as the evidence behind medical and surgical management of obesity in dialysis patients.

Circulating Endocannabinoids and Mortality in Hemodialysis Patients

BACKGROUND

Mortality in patients with end-stage renal disease (ESRD) on maintenance hemodialysis (MHD) remains exceptionally high. While traditional risk factors such as obesity are paradoxically associated with better survival, nontraditional risk factors including cachexia increase the likelihood of poor outcomes. There is accumulating evidence that the endocannabinoid (ECB) system plays a major role in energy preservation and storage, factors which can prevent the deleterious effects of cachexia. Hence, in this study, we evaluated the association of circulating ECB levels with mortality in MHD patients.

METHODS

Serum concentrations of anandamide (AEA) and 2-arachidonoyl-sn-glycerol (2-AG), major ECB ligands, were measured in MHD patients. Their correlation with various clinical/laboratory indices and association with 12-month all-cause mortality were examined.

RESULTS

Serum 2-AG levels positively correlated with body mass index, serum triglycerides and body anthropometric measures. Meanwhile, serum AEA levels correlated positively with serum interleukin-6, and negatively with serum very low-density lipoprotein levels. While increased serum 2-AG levels were associated with reduced risk of all-cause mortality (hazard ratio [HR] 0.52, 95% CI 0.28-0.98), there was no clear association between serum AEA levels and mortality (HR 0.91, 95% CI 0.48-1.72).

CONCLUSIONS

In MHD patients, the circulating levels of ECB ligand, 2-AG, may play an important role in determining body mass and risk of mortality. These observations were unique to 2-AG as similar findings were not obtained with serum AEA. Future studies need to investigate the mechanisms responsible for these associations and examine the modulation of the ECB system as a potential target for therapy in ESRD.

Serum Endocannabinoid Levels in Patients With End-Stage Renal Disease

CONTEXT

Previous studies have shown that the endocannabinoid system plays a major role in energy metabolism through the actions of its main mediators, 2-arachidonoyl-sn-glycerol (2-AG) and anandamide (AEA).

OBJECTIVE

We examined serum levels of major endocannabinoid mediators and their association with clinical parameters in patients with end-stage renal disease (ESRD).

DESIGN AND SETTING

Serum concentrations of 2-AG and AEA were measured in patients on maintenance hemodialysis (MHD) and controls, and correlations with various clinical and laboratory indices were examined. 2-AG was also measured in age and sex-matched healthy subjects for comparison of levels in patients undergoing MHD.

MAIN OUTCOME MEASURE

Serum 2-AG.

RESULTS

Serum 2-AG levels were significantly elevated in patients with ESRD compared with healthy controls. Higher levels of 2-AG were found in patients on MHD compared to healthy subjects, and similar findings were seen in a second set of subjects in independent analyses. Among 96 patients on MHD, 2-AG levels correlated significantly and positively with serum triglycerides (ρ = 0.43; P < 0.0001), body mass index (ρ = 0.40; P < 0.0001), and body anthropometric measures and negatively with serum high-density lipoprotein cholesterol (ρ = -0.33; P = 0.001) following adjustment for demographic and clinical variables.

CONCLUSIONS

In patients on MHD, levels of serum 2-AG, a major endocannabinoid mediator, were increased. In addition, increasing serum 2-AG levels correlated with increased serum triglycerides and markers of body mass. Future studies will need to evaluate the potential mechanisms responsible for these findings.

Racial and Ethnic Disparities in the Obesity Paradox

Obesity is a major risk factor for cardiovascular disease and worse survival in the general population. However, in patients with end-stage renal disease (ESRD), higher body mass index and indexes of body fat and muscle are associated with better survival. Furthermore, these associations, which some have described as the obesity paradox, are more consistent in African American patients being treated with hemodialysis when compared with other racial-ethnic groups. This is in view of data indicating that although the rate of progression to ESRD is faster in African American patients, they have a survival advantage after transition to ESRD when compared with their white counterparts. These observations indicate that there may be significant interaction between race/ethnicity and association of body mass index with outcomes in patients with ESRD. In addition, it is possible that mechanisms underlying improved survival in African American hemodialysis patients are partly related to the association of body mass index with outcomes observed in this patient population. Some of these potential mechanisms may include comparatively reduced risk for protein-energy wasting and malnutrition, possible salutary effects of factors that play a role in energy preservation, resistance to deleterious effects of inflammation, and enhanced muscle mass and body composition. Given that ESRD is associated with significantly increased risk for morbidity and mortality, understanding the pathophysiologic mechanisms responsible for the obesity paradox across race-ethnic populations might help identify potential therapeutic targets that can be used to improve survival in this patient population.

BMI and its association with death and the initiation of renal replacement therapy (RRT) in a cohort of patients with chronic kidney disease (CKD)

Background

A survival advantage associated with obesity has often been described in dialysis patients. The association of higher body mass index (BMI) with mortality and renal replacement therapy (RRT) in preterminal chronic kidney disease (CKD) patients has not been established.

Methods

Subjects were patients with pre-terminal CKD who were recruited to the CKD.QLD registry. BMI at time of consent was grouped as normal (BMI 18.5–24.9 kg/m²), overweight (BMI 25–29.9 kg/m²), mild obesity (BMI 30–34.9 kg/m²) and moderate obesity+ (BMI ≥ 35 kg/m²) as defined by WHO criteria. The associations of BMI categories with mortality and starting RRT were analysed.

Results

The cohort consisted of 3344 CKD patients, of whom 1777 were males (53.1%). The percentages who had normal BMI, or were overweight, mildly obese and moderately obese+ were 18.9, 29.9, 25.1 and 26.1%, respectively. Using people with normal BMI as the reference group, and after adjusting for age, socio-economic status, CKD stage, primary renal diagnoses, comorbidities including cancer, diabetes, peripheral vascular disease (PVD), chronic lung disease, coronary artery disease (CAD), and all other cardiovascular disease (CVD), the hazard ratios (HRs, 95% CI) of males for death without RRT were 0.65 (0.45–0.92, p = 0.016), 0.60 (0.40–0.90, p = 0.013), and 0.77 (0.50–1.19, p = 0.239) for the overweight, mildly obese and moderately obese+. With the same adjustments the hazard ratios for death without RRT in females were 0.96 (0.62–1.50, p = 0.864), 0.94 (0.59–1.49, p = 0.792) and 0.96 (0.60–1.53, p = 0.865) respectively.

In males, with normal BMI as the reference group, the adjusted HRs of starting RRT were 1.15 (0.71–1.86, p = 0.579), 0.99 (0.59–1.66, p = 0.970), and 0.95 (0.56–1.61, p = 0.858) for the overweight, mildly obese and moderately obese+ groups, respectively, and in females they were 0.88 (0.44–1.76, p = 0.727), 0.94 (0.47–1.88, p = 0.862) and 0.65 (0.33–1.29, p = 0.219) respectively.

Conclusions

More than 80% of these CKD patients were overweight or obese. Higher BMI seemed to be a significant “protective” factor against death without RRT in males but there was not a significant relationship in females. Higher BMI was not a risk factor for predicting RRT in either male or female patients with CKD.

Trends in Bariatric Surgery Procedures among Patients with ESKD in the United States

BACKGROUND AND OBJECTIVES

Despite the potential for improving health status or increasing access to transplantation, national practice patterns for bariatric surgery in obese patients with ESKD are poorly understood. The purpose of this study was to describe current trends in surgical care for this population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using 100% Medicare data, we identified all beneficiaries undergoing bariatric surgery in the United States between 2006 and 2016. We evaluated longitudinal practice patterns using linear regression models. We also estimated risk-adjusted complications, readmissions, and length of stay using Poisson regression for patients with and without ESKD.

RESULTS

The number of patients with ESKD undergoing bariatric surgery increased ninefold between 2006 and 2016. The proportional use of sleeve gastrectomy increased from <1% in 2006 to 84% in 2016. For sleeve gastrectomy, complication rates were similar between patients with and without ESKD (3.4% versus 3.6%, respectively; difference, -0.3%; 95% confidence interval, -1.3% to 0.1%; P=0.57). However, patients with ESKD had more readmissions (8.6% versus 5.4%, respectively; difference, 3.2%; 95% confidence interval, 1.9% to 4.6%; P<0.001) and slightly longer hospitals stays (2.2 versus 1.9 days, respectively; difference, 0.3; 95% confidence interval, 0.1 to 0.4; P<0.001).

CONCLUSIONS

This study suggests that laparoscopic sleeve gastrectomy has replaced Roux-en-Y gastric bypass as the most common bariatric surgical procedure in patients with ESKD. The data also demonstrate a favorable complication profile in patients with sleeve gastrectomy.

The obesity paradox: A further consideration in dialysis patients

Several epidemiological cohorts have demonstrated that higher body mass index (BMI) is associated with lower mortality risk among patients receiving hemodialysis. However, BMI may be an inaccurate indicator of nutritional status among dialysis patients because it does not differentiate between muscle and fat mass or provide information about body fat distribution. More sophisticated methods of body composition analysis are therefore required to address the question of which component is associated with greater survival. Recent evidence has also shown that changes in body weight and body composition are more strongly associated with mortality in dialysis patients than measurement of BMI at a single time point. Given that obesity is common among the dialysis population, weight loss interventions are encouraged for obese dialysis patients who are on a transplant waiting list in order to increase the access for transplantation.

Impact of Percent Body Fat on All-Cause Mortality among Adequate Dialysis Patients with and without Insulin Resistance: A Multi-Center Prospective Cohort Study

The association between body fat and mortality in hemodialysis patients remains controversial. We examined the effect of percent body fat (PBF) on all-cause mortality among adequate hemodialysis patients with and without insulin resistance (IR). A prospective cohort study was conducted on 365 adequate hemodialysis patients (equilibrated Kt/V ≥ 1.2) from seven hospitals. Patients’ characteristics and clinical and biochemical parameters were assessed at baseline between September 2013 and April 2017. Patients were followed up for all-cause mortality until April 2018. The median value of homeostatic model assessment (HOMA-IR) was used to classify IR. Cox proportional hazard models were utilized to examine predictors of all-cause mortality. During 1.4 (1.0–3.2) years of follow-up, 46 patients died. In patients with IR (HOMA-IR ≥ 5.18), PBF was significantly higher in the survival group than in the death group (31.3 ± 9.0 vs. 25.4 ± 8.2, p = 0.005). After controlling for confounding factors, PBF was significantly associated with lower risk for all-cause mortality in patients with IR (hazard ratio, 0.94; 95% confidence interval, 0.89–1.00; p = 0.033). The association was not observed in patients without IR. In conclusion, percent body fat shows a protective effect on survival in hemodialysis patients with IR.

Time-varying effects of body mass index on mortality among hemodialysis patients: Results from a nationwide Korean registry

Background

Unlike patterns observed in the general population, obesity is associated with better survival among hemodialysis patients, which could be explained by reverse causation or illness-related weight loss. However, the time-varying effect of body mass index (BMI) on hemodialysis survival has not been investigated. Therefore, this study investigated the time-varying effect of BMI on mortality after starting hemodialysis.

Methods

In the present study, we examined Korean Society of Nephrology data from 16,069 adult patients who started hemodialysis during or after the year 2000. Complete survival data were obtained from Statistics Korea. Survival analysis was performed using Cox regression and a non-proportional hazard fractional polynomial model.

Results

During the median follow-up of 8.6 years, 9,272 patients (57.7%) died. Compared to individuals with normal BMI (18.5–24.9 kg/m²), the underweight group (< 18.5 kg/m²) had a higer mortality hazard ratio (HR, 1.292; 95% confidence interval [CI], 1.203–1.387; P < 0.001) and the overweight group (25.0–29.9 kg/m²) had a lower mortality HR (0.904; 95% CI, 0.829–0.985; P = 0.022). The underweight group had increasing HRs during the first 3 to 7 years after starting hemodialysis, which varied according to age group. The young obese group (< 40 years old) had a U-shaped temporal trend in their mortality HRs, which reflected increased mortality after 7 years.

Conclusion

The obese hemodialysis group had better survival during the early post-dialysis period, although the beneficial effect of obesity disappeared 7 years after starting hemodialysis. The young obese group also had an increased mortality HR after 7 years.

Obesity Paradox in Advanced Kidney Disease: From Bedside to the Bench

While obesity is associated with a variety of complications including diabetes, hypertension, cardiovascular disease and premature death, observational studies have also found that obesity and increasing body mass index (BMI) can be linked with improved survival in certain patient populations, including those with conditions marked by protein-energy wasting and dysmetabolism that ultimately lead to cachexia. The latter observations have been reported in various clinical settings including end-stage renal disease (ESRD) and have been described as the "obesity paradox" or "reverse epidemiology", engendering controversy. While some have attributed the obesity paradox to residual confounding in an effort to "debunk" these observations, recent experimental discoveries provide biologically plausible mechanisms in which higher BMI can be linked to longevity in certain groups of patients. In addition, sophisticated epidemiologic methods that extensively adjusted for confounding have found that the obesity paradox remains robust in ESRD. Furthermore, novel hypotheses suggest that weight loss and cachexia can be linked to adverse outcomes including cardiomyopathy, arrhythmias, sudden death and poor outcomes. Therefore, the survival benefit observed in obese ESRD patients can at least partly be derived from mechanisms that protect against inefficient energy utilization, cachexia and protein-energy wasting. Given that in ESRD patients, treatment of traditional risk factors has failed to alter outcomes, detailed translational studies of the obesity paradox may help identify innovative pathways that can be targeted to improve survival. We have reviewed recent clinical evidence detailing the association of BMI with outcomes in patients with chronic kidney disease, including ESRD, and discuss potential mechanisms underlying the obesity paradox with potential for clinical applicability.

Impact of Obesity on Modality Longevity, Residual Kidney Function, Peritonitis, and Survival Among Incident Peritoneal Dialysis Patients

BACKGROUND

The prevalence of severe obesity, often considered a contraindication to peritoneal dialysis (PD), has increased over time. However, mortality has decreased more rapidly in the PD population than the hemodialysis (HD) population in the United States. The association between obesity and clinical outcomes among patients with end-stage kidney disease remains unclear in the current era.

STUDY DESIGN

Historical cohort study.

SETTING & PARTICIPANTS

15,573 incident PD patients from a large US dialysis organization (2007-2011).

PREDICTOR

Body mass index (BMI).

OUTCOMES

Modality longevity, residual renal creatinine clearance, peritonitis, and survival.

RESULTS

Higher BMI was significantly associated with shorter time to transfer to HD therapy (P for trend < 0.001), longer time to kidney transplantation (P for trend < 0.001), and, with borderline significance, more frequent peritonitis-related hospitalization (P for trend = 0.05). Compared with lean patients, obese patients had faster declines in residual kidney function (P for trend < 0.001) and consistently achieved lower total Kt/V over time (P for trend < 0.001) despite greater increases in dialysis Kt/V (P for trend < 0.001). There was a U-shaped association between BMI and mortality, with the greatest survival associated with the BMI range of 30 to < 35kg/m2 in the case-mix adjusted model. Compared with matched HD patients, PD patients had lower mortality in the BMI categories of < 25 and 25 to < 35kg/m2 and had equivalent survival in the BMI category ≥ 35kg/m2 (P for interaction = 0.001 [vs < 25 kg/m2]). This attenuation in survival difference among patients with severe obesity was observed only in patients with diabetes, but not those without diabetes.

LIMITATIONS

Inability to evaluate causal associations. Potential indication bias.

CONCLUSIONS

Whereas obese PD patients had higher risk for complications than nonobese PD patients, their survival was no worse than matched HD patients.

Association of body weight changes with mortality in incident hemodialysis patients

Background

Incident hemodialysis patients may experience rapid weight loss in the first few months of starting dialysis. However, trends in weight changes over time and their associations with survival have not yet been characterized in this population.

Methods

In a large contemporary US cohort of 58 106 patients who initiated hemodialysis during 1 January 2007-31 December 2011 and survived the first year of dialysis, we observed trends in weight changes during the first year of treatment and then examined the association of post-dialysis weight changes with all-cause mortality.

Results

Patients' post-dialysis weights rapidly decreased and reached a nadir at the 5th month of dialysis with an average decline of 2% from baseline, whereas obese patients (body mass index ≥30 kg/m 2 ) did not reach a nadir and lost ∼3.8% of their weight by the 12th month. Compared with the reference group (-2 to 2% changes in weight), the death hazard ratios (HRs) of patients with -6 to -2% and greater than or equal to -6% weight loss during the first 5 months were 1.08 (95% confidence interval, 1.02-1.14) and 1.14 (1.07-1.22), respectively. Moreover, the death HRs with 2-6% and ≥6% weight gain during the 5th to 12th months were 0.91 (0.85-0.97) and 0.92 (0.86-0.99), respectively.

Conclusions

In patients who survive the first year of hemodialysis, a decline in post-dialysis weight is observed and reaches a nadir at the 5th month. An incrementally larger weight loss during the first 12 months is associated with higher death risk, whereas weight gain is associated with greater survival during the 5th to 12th month but not in the first 5 months of dialysis therapy.

Time to redefine body mass index categories in chronic diseases? Spotlight on obesity paradox

Obesity is a complex condition classically characterised by excessive body fat accumulation and represents one of the most important public health problems worldwide. Although several epidemiological studies have shown that elevated BMI is associated with higher morbidity, and with increased rate of death from all causes and from cardiovascular disease, accumulating evidence suggests that being overweight or obese may be protective (the so-called obesity paradox), at least in chronic diseases. These observations, not only question the validity of the BMI system, but also raise the intriguing question of whether we should redefine what the normal range of BMI is in individuals suffering from a chronic disease. In the present article, we review the available information on the association between elevated BMI and increased morbidity and mortality including obesity-related paradoxes, explore key aspects of the role and limitations of BMI as a measure of increased adiposity and outline potential solutions to address the current controversies regarding the impact of obesity on human health.

The Diet and Haemodialysis Dyad: Three Eras, Four Open Questions and Four Paradoxes. A Narrative Review, Towards a Personalized, Patient-Centered Approach

The history of dialysis and diet can be viewed as a series of battles waged against potential threats to patients' lives. In the early years of dialysis, potassium was identified as "the killer", and the lists patients were given of forbidden foods included most plant-derived nourishment. As soon as dialysis became more efficient and survival increased, hyperphosphatemia, was identified as the enemy, generating an even longer list of banned aliments. Conversely, the "third era" finds us combating protein-energy wasting. This review discusses four questions and four paradoxes, regarding the diet-dialysis dyad: are the "magic numbers" of nutritional requirements (calories: 30-35 kcal/kg; proteins > 1.2 g/kg) still valid? Are the guidelines based on the metabolic needs of patients on "conventional" thrice-weekly bicarbonate dialysis applicable to different dialysis schedules, including daily dialysis or haemodiafiltration? The quantity of phosphate and potassium contained in processed and preserved foods may be significantly different from those in untreated foods: what are we eating? Is malnutrition one condition or a combination of conditions? The paradoxes: obesity is associated with higher survival in dialysis, losing weight is associated with mortality, but high BMI is a contraindication for kidney transplantation; it is difficult to limit phosphate intake when a patient is on a high-protein diet, such as the ones usually prescribed on dialysis; low serum albumin is associated with low dialysis efficiency and reduced survival, but on haemodiafiltration, high efficiency is coupled with albumin losses; banning plant derived food may limit consumption of "vascular healthy" food in a vulnerable population. Tailored approaches and agreed practices are needed so that we can identify attainable goals and pursue them in our fragile haemodialysis populations.

Risks of Adverse Events in Advanced CKD: The Chronic Renal Insufficiency Cohort (CRIC) Study

BACKGROUND

People with advanced chronic kidney disease are at risk for the development of end-stage renal disease (ESRD), but also many other adverse outcomes, including cardiovascular disease (CVD) events and death. Determination of risk factors that explain the variability in prognosis and timing of these adverse outcomes can aid patient counseling and medical decision making.

STUDY DESIGN

Prospective research cohort.

SETTING & PARTICIPANTS

1,798 participants with estimated glomerular filtration rates (eGFRs)<30mL/min/1.73m² in the CRIC Study were followed up for a median of 5.5 years.

PREDICTORS

Age, race, sex, eGFR, proteinuria, diabetes mellitus, body mass index, ejection fraction, systolic blood pressure, history of CVD, and smoking history.

OUTCOMES

ESRD, CVD (congestive heart failure, stroke, myocardial infarction, and peripheral artery disease), and death.

RESULTS

Baseline age of the cohort was 60 years, 46% were women, and 46% were African American. Although 52.3% of participants progressed to ESRD during follow-up, the path by which this occurred was variable. For example, predicted 1-year probabilities for a hypothetical 60-year-old white woman with eGFR of 30mL/min/1.73m², urine protein excretion of 1.8g/d, and no diabetes or CVD (risk characteristics similar to the average participant) were 3.3%, 4.1%, and 0.3%, for first developing CVD, ESRD, and death, respectively. For a 40-year-old African American man with similar characteristics but higher systolic blood pressure, the corresponding 1-year probabilities were 2.4%, 13.2%, and 0.1%. For all participants, the development of ESRD or CVD increased the risk for subsequent mortality, with no differences by patient race or body mass index.

LIMITATIONS

The CRIC population was specifically recruited for kidney disease, and the vast majority had seen a nephrologist.

CONCLUSIONS

The prognosis and timing of adverse outcomes in chronic kidney disease vary by patient characteristics. These results may help guide the development of personalized approaches for managing patients with advanced CKD.

The Obesity Paradox in Kidney Disease: How to Reconcile it with Obesity Management

Obesity, a risk factor for de novo chronic kidney disease (CKD), confers survival advantages in advanced CKD. This so-called obesity paradox is the archetype of the reverse epidemiology of cardiovascular risks, in addition to the lipid, blood pressure, adiponectin, homocysteine, and uric acid paradoxes. These paradoxical phenomena are in sharp contradistinction to the known epidemiology of cardiovascular risks in the general population. In addition to advanced CKD, the obesity paradox has also been observed in heart failure, chronic obstructive lung disease, liver cirrhosis, and metastatic cancer, as well as in the elderly. These are populations in whom protein-energy wasting and inflammation are strong predictors of early death. Both larger muscle mass and higher body fat provide longevity in these patients, whereas thinner body habitus and weight loss are associated with higher mortality. Muscle mass appears to be superior to body fat in conferring an even greater survival. The obesity paradox may be the result of a time discrepancy between competing risk factors, i.e., overnutrition as the long-term killer versus undernutrition as the short-term killer. Hemodynamic stability of obesity, lipoprotein defense against circulating endotoxins, protective cytokine profiles, toxin sequestration of fat mass, and antioxidation of muscle may play important roles. Despite claims that obesity paradox is a statistical fallacy and a result of residual confounding, the consistency of data and other causality clues suggest a high biologic plausibility. Examining the causes and consequences of the obesity paradox may help discover important pathophysiologic mechanisms leading to improved outcomes in patients with CKD.

The dual roles of obesity in chronic kidney disease: a review of the current literature

PURPOSE OF REVIEW

Obesity is a major risk factor for the development of de novo chronic kidney disease (CKD). However, once kidney disease is acquired, obesity is paradoxically linked with greater survival, especially in those with advanced CKD. This review examines current evidence for obesity as a risk factor for incident CKD, studies of obesity and mortality across various CKD populations, and potential mechanisms underlying the 'obesity paradox' in kidney disease.

RECENT FINDINGS

Large cohort studies show that overweight body habitus, especially in the context of metabolic syndrome, is associated with higher risk of incident CKD. Emerging data also suggest weight-loss interventions retard or reverse early CKD progression, whereas in hemodialysis patients weight-loss paradoxically heralds poor outcomes. Although the pathogenesis of CKD in obesity remains unclear, studies indicate that excess body fat leads to kidney disease via indirect and direct mechanisms. Meta-analyses suggest that overweight and obese BMI ranges are counterintuitively associated with lower mortality in advanced predialysis and dialysis-dependent CKD patients, whereas a pooled analysis observed that higher pretransplantation BMI was associated with higher mortality in kidney transplantation recipients.

SUMMARY

In addition to its role as a risk factor for de novo CKD, there appears to be a consistent association between obesity and lower mortality in those with established CKD, particularly among hemodialysis patients, suggesting that the reverse epidemiology of obesity is biologically plausible.

Interaction between acyl-ghrelin and BMI predicts clinical outcomes in hemodialysis patients

Background

Ghrelin, a gastric orexigenic peptide, and body mass index (BMI) are known as inversely associated to each other and are both linked to cardiovascular (CV) risk and mortality in maintenance hemodialysis (MHD) patients. However, it is unclear whether the interaction between ghrelin and BMI is associated with a risk of all-cause and CV death in this population.

Methods

A prospective observational study was performed on 261 MHD outpatients (39% women, mean age 68.6 ± 13.6 years) recruited from October 2010 through April 2012, and were followed until November 2014 (median follow-up-28 months, interquartile range-19–34 months). We measured acyl-ghrelin (AG) levels, appetite, nutritional and inflammatory markers, prospective all-cause and cardiovascular (CV) mortality.

Results

During follow-up, 109 patients died, 51 due to CV causes. A significant interaction effect of high BMI and high AG (defined as levels higher than median) on all-cause mortality was found. Crude Cox HR for the product termed BMI x AG was 0.52, with a 95% confidence interval (CI): 0.29 to 0.95 (P = 0.03). Evaluating the interaction on an additive scale revealed that the combined predictive value of BMI and AG is larger than the sum of their individual predictive values (synergy index was 1.1). Across the four BMI-AG categories, the group with high BMI and high AG exhibited better all-cause and cardiovascular mortality irrespective of appetite and nutritional status (multivariable adjusted hazard ratios were 0.31, 95% CI 0.16 to 0.62, P = 0.001, and 0.35, 95% CI 0.13 to 0.91, P = 0.03, respectively). Data analyses made by dividing patients according to fat mass-AG, but not to lean body mass-AG categories, provided similar results.

Conclusions

Higher AG levels enhance the favourable association between high BMI and survival in MHD patients irrespective of appetite, nutritional status and inflammation.

Preoperative assessment of surgical risk: creation of a scoring tool to estimate 1-year mortality after emergency abdominal surgery in the elderly patient

BACKGROUND

The risk of mortality after emergency general surgery (EGS) in elderly patients is prolonged beyond initial hospitalization. Our objective was to develop a preoperative scoring tool to quantify risk of 1-year mortality.

METHODS

Three hundred ninety EGS patients aged 70 years or more were analyzed. Risk factors for 1-year mortality were identified using stepwise-forward logistic multivariate regression and weights assigned using natural logarithm of odds ratios. A geriatric emergency surgery mortality (GEM) score was derived from the aggregate of weighted scores. Leave-one-out cross-validation was performed.

RESULTS

One-year mortality was 32%. Risk factors and their weights were: acute kidney injury (2), American Society of Anesthesiology class greater than or equal to 4 (2), Charlson Comorbidity Index greater than or equal to 4 (1), albumin less than 3.5 mg/dL (1), and body mass index (less than 18.5 kg/m² [1]; 18.5 to 29.9 kg/m² [0]; ≥30 kg/m² [-1]). One-year mortality was: GEM 0 to 1 (0% to 7%); GEM 2 to 5 (32% to 68%); GEM 6 to 8 (94% to 100%). C-statistics were .82 and .75 in training and validation data sets, respectively.

CONCLUSIONS

A simple score using 5 clinical variables predicts 1-year mortality after EGS with reasonable accuracy and assists in preoperative counseling.