The influence of obesity on the development and survival outcomes of chronic kidney disease

Automated 3D-Body Composition Analysis as a Predictor of Survival in Patients With Idiopathic Pulmonary Fibrosis

PURPOSE

Idiopathic pulmonary fibrosis (IPF) is the most common interstitial lung disease, with a median survival time of 2 to 5 years. The focus of this study is to establish a novel imaging biomarker.

MATERIALS AND METHODS

In this study, 79 patients (19% female) with a median age of 70 years were studied retrospectively. Fully automated body composition analysis (BCA) features (bone, muscle, total adipose tissue, intermuscular, and intramuscular adipose tissue) were combined into Sarcopenia, Fat, and Myosteatosis indices and compared between patients with a survival of more or less than 2 years. In addition, we divided the cohort at the median (high=≥ median, low=

RESULTS

A high Sarcopenia and Fat index and low Myosteatosis index were associated with longer median survival (35 vs. 16 mo for high vs. low Sarcopenia index, P=0.066; 44 vs. 14 mo for high vs. low Fat index, P<0.001; and 33 vs. 14 mo for low vs. high Myosteatosis index, P=0.0056) and better 5-year survival rates (34.0% vs. 23.6% for high vs. low Sarcopenia index; 47.3% vs. 9.2% for high vs. low Fat index; and 11.2% vs. 42.7% for high vs. low Myosteatosis index). Adjusted multivariate Cox regression showed a significant impact of the Fat (HR=0.71, P=0.01) and Myosteatosis (HR=1.12, P=0.005) on overall survival.

CONCLUSION

The fully automated BCA provides biomarkers with a predictive value for the overall survival in patients with IPF.

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Affiliation(s)

Luca Salhöfer Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany Institute for Artificial Intelligence in Medicine, University Hospital Essen, Essen, Germany
Francesco Bonella Department of Pneumology, Center for Interstitial and Rare Lung Diseases, University Hospital Essen, Essen, Germany
Mathias Meetschen Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany Institute for Artificial Intelligence in Medicine, University Hospital Essen, Essen, Germany
Lale Umutlu Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany
Michael Forsting Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany
Benedikt Michael Schaarschmidt Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany
Marcel Klaus Opitz Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany
Jens Kleesiek Institute for Artificial Intelligence in Medicine, University Hospital Essen, Essen, Germany
Rene Hosch Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany Institute for Artificial Intelligence in Medicine, University Hospital Essen, Essen, Germany
Sven Koitka Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany Institute for Artificial Intelligence in Medicine, University Hospital Essen, Essen, Germany
Vicky Parmar Institute for Artificial Intelligence in Medicine, University Hospital Essen, Essen, Germany
Felix Nensa Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany Institute for Artificial Intelligence in Medicine, University Hospital Essen, Essen, Germany
Johannes Haubold Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany Institute for Artificial Intelligence in Medicine, University Hospital Essen, Essen, Germany

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Modifiable kidney disease risk factors among nondiabetic adults with obesity from the Multi-Ethnic Study of Atherosclerosis

OBJECTIVE

It is unknown whether weight change or physical fitness is associated with chronic kidney disease (CKD) risk among nondiabetic adults with obesity.

METHODS

This was a prospective, longitudinal cohort study of adults with obesity without baseline CKD or diabetes enrolled in the Multi-Ethnic Study of Atherosclerosis (MESA). Linear mixed-effects and multistate models were adjusted for demographics, time-varying covariates including blood pressure, and comorbidities these were used to examine associations of weight change and slow walking pace (<2 miles/h) with (i) rate of annual estimated glomerular filtration rate (eGFR) decline and (ii) incident CKD, defined as eGFRCr-Cys  < 60 mL/min/1.73 m2 , and tested for interaction by baseline hypertension status.

RESULTS

Among 1208 included MESA participants (median BMI 33.0 kg/m2 [interquartile range 31.2-35.9]), 15% developed CKD. Slow walking pace was associated with eGFR decline (-0.27 mL/min/1.73 m2 /year; 95% CI: -0.42 to -0.12) and CKD risk (adjusted hazard ratio 1.48; 95% CI: 1.08 to 2.01). Weight gain was associated with CKD risk (adjusted hazard ratio 1.34; 95% CI: 1.02 to 1.78 per 5 kg weight gain from baseline). There was no significant interaction by baseline hypertension status.

CONCLUSIONS

Slow walking pace and weight gain were associated with CKD risk among adults with obesity who did not have diabetes at baseline.

What is the Optimal Fat Mass in Peritoneal Dialysis Patients?

The prevalence of obesity in peritoneal dialysis (PD) populations has risen dramatically since the mid-1980s. This epidemic has been driven by the increased prevalence of obesity in the general population, the increased risk of progression of chronic kidney disease to end-stage renal failure (ESRF) in obese subjects, the reduced probability of listing obese dialysis patients for renal transplantation, a paradoxical enhanced survival in at least some obese populations on dialysis as compared with non-obese ESRF patients, and a possible adipogenic effect of excessive peritoneal glucose absorption in PD. Although obesity has consistently been associated with improved outcomes in hemodialysis, conflicting results have been seen in PD. In general, an elevated body mass index (BMI) has been associated with a neutral or deleterious impact on PD outcomes, and the relationship appears to be explained predominantly by fat mass. Risk is also elevated in patients with a low BMI, such that the “optimal BMI” appears to lie between 20 kg/m2 and 25 kg/m2. The mechanisms underpinning the harmful effect of obesity appear to include increased peritonitis rate, proinflammatory effects, and a more rapid decline of residual renal function in obese patients. No proof exists that weight reduction engenders an improvement in outcome in PD patients, but the available studies suggest that cautious weight reduction is advisable. A few studies have demonstrated that clinically important and sustained weight reduction can be successfully achieved through a combination of individual meal plans, regular exercise, and substitution of icodextrin for dextrose in the once-daily long dwell.

Metabolic Syndrome Rather than Obesity Alone Is More Significant for Kidney Disease

INTRODUCTION

Obesity is associated with metabolic syndrome, nonalcoholic steatohepatitis, and kidney disease. BMI may not be the ideal measure of obesity when used to assess its effect on kidney disease as it does not discriminate for age, sex, ethnicity, muscle, bone, or fat mass.

OBJECTIVES

To assess the prevalence microalbuminuria and identify independent risk factors for development of kidney disease in the obese Indian population.

METHODS

Age, weight, BMI, total body fat percentage, waist-to-hip ratio, hypertension, urinary albumin-to-creatinine ratio (UACR), and HbA1c were collected from 568 obese patients, presenting for bariatric surgery. Multivariate binary logistic regression was used to identify independent risk factors for kidney disease.

RESULTS

A total of 114 out of 568 (20.07%) obese patients had microalbuminuria (UACR range 30-283 μg/mg). HbA1C levels ≥ 6 (p = 0.01) and hypertension (p = 0.03) were the strongest independent variables for microalbuminuria. 14.67% with a BMI < 35 kg/m², 21.30% with a BMI 35-50 kg/m², and 19.44% with a BMI > 50 kg/m² had microalbuminuria. Increasing BMI however was not statistically significant (p = 0.75). Total body fat percentage (p = 0.51), waist-to-hip ratio (p = 0.96), age (p = 0.30), sex (p = 0.38), and BMI (p = 0.75) were found to be statistically insignificant.

CONCLUSIONS

Kidney disease afflicts 1/5th of the obese Indian patients studied. Diabetes and hypertension remained as the most significant risk factors, while age, weight, increasing BMI, waist-to-hip ratio, or increasing body fat were found to be statistically insignificant for development and progression of kidney disease.

Effect of 12-month nasal continuous positive airway pressure therapy for obstructive sleep apnea on progression of chronic kidney disease

BACKGROUND

Obstructive sleep apnea (OSA) is common among patients with chronic kidney disease (CKD). CKD may increase the risk of OSA, and OSA may increase the risk of renal injury. Nasal continuous positive airway pressure (nCPAP) is the standard treatment for OSA. However, the effect of nCPAP on the progression of CKD is unclear.

METHODS

A total of 395 patients with stage 3/4 CKD were initially examined, and 269 patients (148 non-OSA cases; 79 mild OSA cases; 42 moderate/severe OSA cases) were analyzed after implementation of the exclusion criteria. The severity of OSA was determined by polysomnography (PSG). Fifty-two OSA patients (32 mild OSA cases; 20 moderate/severe OSA cases) received nCPAP treatment for 12 months. Variables associated with OSA severity and estimated glomerular filtration rate (eGFR) were evaluated before and after the 12-month nCPAP treatment.

RESULTS

Among all 269 CKD patients, body mass index (BMI), and eGFR had significant associations with OSA severity. Age, BMI, apnea-hypopnea index (AHI), mean SaO2%, and SaO2 <90% monitoring time had independent associations with lower eGFR. The 12-month nCPAP treatment significantly reduced the rate of eGFR decline. Univariate and multivariate analysis indicated that age, BMI, AHI, mean SaO2%, and SaO2 <90% monitoring time were independently associated with reduced eGFR. Furthermore, nCPAP treatment significantly improved eGFR, AHI, mean SaO2, and SaO2 <90% monitoring time in patients with mild OSA, and improved systolic/diastolic blood pressure, urinary protein level, eGFR, AHI, mean SaO2, and SaO2 <90% monitoring time for patients with moderate/severe OSA.

CONCLUSION

This study of patients with CKD and OSA indicated that nCPAP therapy significantly ameliorated CKD progression, especially in those with moderate/severe OSA.

Estimating Negative Effect of Abdominal Obesity on Mildly Decreased Kidney Function Using a Novel Index of Body-Fat Distribution

Abdominal obesity is a major risk factor of chronic kidney disease (CKD). Conventional obesity-related indicators, included body mass index (BMI), waist circumference (WC), and conicity index (C-index), have some limitations. We examined the usefulness of trunk/body fat mass ratio (T/Br) to predict negative effect of abnormal fat distribution on excretory kidney function. We analyzed anthropometric, biochemical and densitometric data from a nation-wide, population-based, case-control study (the Korean National Health and Nutrition Examination Survey [KNHANES] IV and V). A total of 11,319 participants were divided into 2 groups according to estimated glomerular filtration rate (eGFR, mL·min⁻¹·1.73 m⁻²) as follows: Group I (n = 7,980), eGFR ≥ 90 and ≤ 120; and group II (n = 3,339), eGFR ≥ 60 and < 90. Linear regression analysis revealed that T/Br was closely related to eGFR (β = -0.3173, P < 0.001), and the correlation remained significant after adjustment for age, gender, BMI, WC, C-index, systolic blood pressure (BP), hemoglobin, and smoking amount (β = -0.0987, P < 0.001). Logistic regression analysis showed that T/Br (odds ratio [OR] = 1.046; 95% confidence interval [CI] = 1.039-1.054) was significantly associated with early decline of kidney function, and adjustment for age, gender, BMI, C-index, systolic BP, hemoglobin, serum glucose level, high-density lipoprotein (HDL)-cholesterol, and smoking amount did not reduce the association (OR = 1.020; 95% CI = 1.007-1.033). T/Br is useful in estimating the negative impact of abdominal obesity on the kidney function.

Knowledge, Attitude, and Behaviors Related to Eating Out among University Students in China

In many countries the frequency of eating out has steadily increased over the last few decades, and this behavioris often associated with unhealthy dietary patterns. This study aimed to describe the levels of knowledge, attitude, and behaviors (KAB) related to eating out among university students. A cross-sectional study was conducted in the college town in Chongqing, China with a total of 1634 participants. The mean eating out related KAB scores were: knowledge 11.5 ± 2.9, attitude 17.0 ± 2.8, and behaviors 24.2 ± 4.8 (possible total scores: 20, 24, 40 respectively). As the level of knowledge increased, the percentage of highly satisfactory attitude and behaviors increased. Only 10% of the participants did not eat out for lunch and dinner during weekends in the last month. Gender, ethnicity, mother’s education, monthly boarding expenses, living place during the study, and the frequency of eating out for breakfast were statistically associated with the scores of KAB. In conclusion, Chinese junior students had poor knowledge of and behaviors towards eating out and ate out frequently. Educational interventionsto improve knowledge related eating out are needed in order to promote healthy eating out behaviors among Chinese university students.

Is high body mass index independently associated with diminished glomerular filtration rate? An epidemiological study

AIM

To examine whether there is an independent association between body mass index (BMI) and estimated glomerular filtration rate (GFR) in a large primary care population.

METHODS

Anonymous data were sequentially extracted from primary care records between 2006 and 2009 in a primary care population of approximately 220,000 people in Kent, South East UK. Using GFR, BMI, age, gender and comorbidities we examined the association between BMI and GFR. Univariate and multivariate analysis was performed using SPSS(®) (SPSS Inc., Chicago).

RESULTS

Sixty-one thousand six-hundred thirty seven people fulfilled the inclusion criteria. There was no correlation between BMI and GFR on univariate analysis. When stratified by BMI, ANOVA demonstrated a statistically significant difference in GFR across BMI strata (p < 0.001). However the absolute differences in BMI between groups were very small. There was a small association between BMI and GFR on multivariate analysis, much of which was lost on adjustment for confounding variables.

CONCLUSION

These findings suggest that elevated BMI is not a biologically significant predictor of diminished GFR and therefore may be an insufficiently accurate measure of risk for the metabolic syndrome and CKD.

Cannabinoid CB1 receptor expression in relation to visceral adipose depots, endocannabinoid levels, microvascular damage, and the presence of the Cnr1 A3813G variant in humans

Dysregulation of the endocannabinoid system in the visceral adipose tissue (VAT) is associated with metabolic and cardiovascular complications of obesity. We studied perirenal VAT CB1 receptor expression in relation to anthropometry, VAT area and endocannabinoid levels, kidney microvascular damage (MVDa), and the presence of the CB1 gene A3813G variant, the frequency of which was also evaluated in a large population of obese-hypertensive (OH) patients with or without the metabolic syndrome (MetS). Perirenal VAT and kidney samples were obtained from 30 patients undergoing renal surgery. Total and perirenal VAT areas were determined by computed tomography. CB1 messenger RNA expression and endocannabinoid levels in perirenal VAT were determined by quantitative reverse transcriptase polymerase chain reaction and liquid chromatography-mass spectrometry, respectively. The MVDa was evaluated in healthy portions of kidney cortex. The A3813G alleles were identified by genotyping in these patients and in 280 nondiabetic OH patients (age <or=65 years). Metabolic syndrome was defined according to the Adult Treatment Panel III criteria. Perirenal VAT CB1 expression was 40% lower in patients with the A3813G polymorphism, and correlated positively with perirenal and total VAT area and with perirenal VAT levels of the endocannabinoid anandamide. A 2-fold higher CB1 expression was associated with MVDa. The OH patients with the A3813G allele had lower prevalence of MetS in both unadjusted and adjusted models. Genetics influence perirenal VAT CB1 expression and the prevalence of MetS in OH. Increased VAT is associated with increased perirenal VAT endocannabinoid tone, which in turn correlates with increased MVDa. Endocannabinoid overactivity might be involved in human visceral obesity and its renal complications.

Effects of Anthropometric Measurements on Renal Function

Although the negative effect of increased body mass index on kidney has been examined, the relation between other anthropometric measurements and kidney functions has not been investigated sufficiently. This study looks at the influence of anthropometric measurements on kidney functions. Forty patients were included in the study. Patients who had increased or normal anthropometric measurements were compared by serum levels of the urea, creatinine, albumin, 24 hr urine creatinine clearance, and urinary albumin excretion rate (UAER). Of all patients, 22 (55%) had an increased body mass index (BMI), 19 (47.5%) had an increased waist circumference (WC), and 24 (60%) had an increased waist-hip ratio (WHR). Subjects with increased BMI, WC, and WHR had significantly higher levels of serum creatinine and UAER than the subjects with normal measurements. The relation between CC and BMI was statistically significant only among the anthropometric measurements (p = 0.026). The ratio of microalbuminuria was 27.3%, 21.1%, and 29.2% in persons with increased BMI, WC, and WHR, respectively. Increases of anthropometric measurements affect kidney functions negatively. However, the influence of BMI on kidney function is more prominent. For this reason; individuals with increased anthropometric measurements should be monitored closely in terms of renal functions additional to cardiovascular risk factors.

Comparison of overall obesity and abdominal adiposity in predicting chronic kidney disease incidence among adults

OBJECTIVE

Epidemiological data on the association between different aspects of adiposity and the risk for chronic kidney disease (CKD) in a cohort are limited. We compared the independent power of waist circumference (WC), waist-to-hip ratio (WHR), and body mass index (BMI) in predicting CKD in a large cohort of adults.

DESIGN

This was a population-based cohort study.

SETTING, PARTICIPANTS, AND MEASUREMENTS

A representative sample of 3107 subjects (1309 men and 1798 women), aged over 20 years, and free of CKD at baseline, was followed for 7 years.

METHODS

We estimated glomerular filtration rate (GFR) by using the abbreviated equation from the Modification of Diet in Renal Disease Study, and defined CKD as an estimated GFR of less than 60 mL/min/1.73 m(2). Adjusted relative hazards of CKD were modeled using Cox proportional hazards regression, including BMI, WC, and WHR as risk factors.

RESULTS

During the 7-year follow-up (median of 2183 days), 13.5% of participants (n = 419) developed CKD. The WC was positively related to risk of CKD, after multivariable adjustment for age, sex, smoking, menopause, physical activity, blood pressure, prevalent and incident diabetes, and change in WC during study period: Hazard ratios for CKD incidence were 1.00 (reference), 1.60 (95% CI: 1.06, 2.42), 1.86 (0.95 CI: 1.21, 2.85), and 1.88 (0.95 CI: 1.17, 3.01) for WC categories 1 to 4, respectively (P for trend < .02). The WHR was not independently associated with CKD. The rate of GFR decline (measured in mL/min/1.73 m(2)/year) was associated with baseline waist categories: regression coefficient for 1 SD increase in WC = -0.18 (0.95 CI:-0.28, -0.07). Based on Harrell's measure of concordance statistics, baseline WC was a better predictor of CKD than WHR (P < .05) and BMI (P < .05).

CONCLUSIONS

Abdominal adiposity measured with WC, irrespective of general adiposity, is a more important determinant of CKD risk in adults than are WHR and BMI.

Association between waist-to-hip ratio and chronic kidney disease in the elderly

BACKGROUND

To compare the anthropometric indices of obesity and identify which index serves as a better discriminator in the chronic kidney disease (CKD) for the elderly.

METHODS

Participants of a 1-day health check, older than 60 years, in our hospital from 2003 to 2005 were enrolled. CKD was defined as estimated glomerular filtration rate by modification of diet in renal disease formula less than 60 mL/min per 1.73 m(2). Indices of obesity include body mass index, waist circumference, waist-to-hip ratio (WHR) and waist-to-height ratio. Traditional risk factors including diabetes, hypertension and metabolic syndrome were also taken into consideration. The accuracy of indices of obesity in predicting CKD was measured by area under the receiver operating characteristic curve (AUC). Association between risk factors was estimated by multivariate logistic regression.

RESULTS

We studied 984 participants (537 men and 447 women) with a mean age of 66.7 +/- 5.3 years. A total of 161 (16.4%) participants was found having CKD. In the indices of obesity, WHR showed best diagnostic accuracy in predicting CKD (AUC: 0.58). A WHR cut-off value of 0.88 had a sensitivity of 68.9% and a specificity of 45.4%. The odds ratios were significant for WHR, hypertension and diabetes (P = 0.025, P < 0.001 and P = 0.033).

CONCLUSION

In indices of obesity, WHR is better than body mass index, bodyweight and waist circumferences in predicting CKD in elder Taiwanese. Furthermore, the association of WHR and CKD is independent of hypertension and diabetes.

Association between obesity and kidney disease: a systematic review and meta-analysis

This study aimed to comprehensively assess epidemiologic evidence on the relation between obesity and kidney disease (KD). From 247 retrieved articles via PubMed (1980-2006), 25 cohorts, 3 cross-sectional, and 19 case-control studies met inclusion criteria. Related data were extracted using a standardized protocol. We estimated the pooled relative risk (RR) and 95% confidence interval (95% CI) of KD for each body mass index (BMI) category compared with normal weight using meta-analysis models. Population attributable risk was also calculated. Compared with normal-weight individuals (18.5<BMI<25), overweight individuals (25< or =BMI<30) had elevated risk for KD (RR=1.40; 95% CI 1.30-1.50); obese individuals were at much higher risk (RR=1.83 (1.57-2.13)). Obesity in women was associated with a higher risk than in men (RR=1.92 (1.78-2.07) vs 1.49 (1.36-1.63); P<0.001). Results from cohort studies in patient populations and cross-sectional and case-control studies all indicated a positive association between BMI and risks for KD outcomes. We estimated that 24.2% and 33.9% of KD cases among US men and women, respectively, and in industrialized countries, 13.8% in men and 24.9% in women, could be related to overweight and obesity. Obesity increases the risk for KD in the general population, and the association appears to be stronger in women than in men. Obesity adversely affects the progress of KD among patients with kidney-related diseases.

Safety and efficacy of bariatric surgery: Longitudinal Assessment of Bariatric Surgery

BACKGROUND

Obesity is a leading health concern in the United States. Because traditional treatment approaches for weight loss are generally unsuccessful in the long term, bariatric surgical procedures are increasingly being performed to treat extreme obesity. To facilitate research in this field, the National Institute of Diabetes and Digestive and Kidney Diseases responded to this knowledge gap by establishing the Longitudinal Assessment of Bariatric Surgery (LABS) consortium.

METHODS

A competitive National Institute of Diabetes and Digestive and Kidney Diseases grant process resulted in the creation of a group of investigators with expertise in bariatric surgery, internal medicine, endocrinology, behavioral science, outcomes research, epidemiology, biostatistics, and other relevant fields. These investigators have worked closely to plan, develop, and conduct the LABS study. The LABS consortium protocol is a prospective, multicenter observational cohort study of consecutive patients undergoing bariatric surgery at 6 clinical centers. LABS includes an extensive database of information systematically collected preoperatively, at surgery, perioperatively during the 30-day postoperative period, and longer term.

RESULTS

The LABS study has been organized into 3 phases. LABS-1 will include all patients > or =18 years of age who have undergone bariatric surgery by LABS-certified surgeons with the goal to evaluate the short-term safety of bariatric surgery. LABS-2, a subset of approximately 2400 LABS-1 patients, will evaluate the relationship of patient and surgical characteristics to the longer term safety and efficacy of bariatric surgery. LABS-3 will involve a subset of LABS-2 subjects who will undergo detailed studies of mechanisms involved in weight change. The rationale, goals, and approach to study bariatric surgery are detailed in this report, along with a description of the outcomes, measures, and hypotheses used in LABS-1 and -2.

CONCLUSION

The goal of the LABS consortium is to accelerate clinical research and understanding of extreme obesity and its complications by evaluating the risks and benefits of bariatric surgery. LABS investigators use standardized definitions, high-fidelity data collection, and validated instruments to enhance the ability of clinicians to provide meaningful evidence-based recommendations for patient evaluation, selection for surgery, and follow-up care.

Managing the Burden of Chronic Kidney Disease

Patients with chronic kidney disease (CKD) have high rates of healthcare utilization, morbidity, and mortality. Increasing rates of obesity, diabetes, and hypertension suggest that the expected numbers of patients with CKD will rise. Managing the economic and clinical burden of CKD will be a significant challenge for the healthcare system. The burden of CKD can be considered in terms of both CKD-specific and CKD-related morbidity and mortality. CKD-specific complications include anemia and bone disease. CKD-related complications include obesity, diabetes and hypertension. CKD-specific complications tend to occur later in the course of disease and may be best treated by a nephrologist, while CKD-related complications may be most easily treated by primary care physicians. Coordinating patient care is essential to managing the burden of this growing disease.