Central body fat distribution associates with unfavorable renal hemodynamics independent of body mass index

Prevalence of Obstructive Sleep Apnea Among Lebanese Patients With Chronic Kidney Disease: Its Repercussion on Disease Trajectory and Its Effect on Patients' Quality of Life

Background and Objectives: Chronic kidney disease (CKD) remains a public health threat and a major cause of morbidity and mortality worldwide. A bidirectional relationship is found between sleep disorders and CKD worldwide. However, to our knowledge, this study is the first to assess the prevalence of obstructive sleep apnea (OSA) and to evaluate its impact on the progression of other comorbidities among Lebanese patients with CKD. Materials and Methods: The study is an observational cross-sectional study, carried out between September and November 2021. Lebanese patients with any stage of CKD were included. Patients' characteristics were collected via electronic health record and baseline questionnaires. We screened for obstructive sleep apnea using the STOP-Bang questionnaire. Results: We included 168 patients. The prevalence of OSA among our patients was 47.6%. The prevalence of OSA is higher in males compared with females (81.2% vs. 18.8%, p=0.002). Obesity was more prevalent in patients with OSA compared with patients without OSA (42.5% vs. 19.3%, p=0.002). Among the 168 patients, 69.6% had hypertension, with a significantly higher prevalence among those with OSA compared with those without OSA (81.2% vs. 59.1%, p=0.003). Patients with OSA reported significantly lower scores compared with those without OSA in several domains of physical and emotional health, including physical functioning (54.06 vs. 66.88, p=0.002), role limitations due to physical health (42.19 vs. 63.07, p=0.001), role limitations due to emotional problems (49.17 vs. 69.32, p=0.004), pain (61.31 vs. 70.45, p=0.019), and physical component score (52.53 vs. 69.53, p=0.002). All the abovementioned parameters were also examined in two subpopulations: patients with CKD and ESRD. Similarly, some comorbidities and a lower physical QOL score were observed more in patients with OSA in these two subpopulations. Conclusion: Patients with OSA in our study have higher probability of being male, obese, and hypertensive as well as poorer QOL compared with their counterparts without OSA. Implementing more effective screening and treatment of OSA in CKD patients is necessary.

Higher abdominal fat area associates with lower donor kidney function before and after living kidney donation

Central body fat distribution affects kidney function. Abdominal fat measurements using computed tomography (CT) may prove superior in assessing body composition-related kidney risk in living kidney donors. This retrospective cohort study including 550 kidney donors aimed to determine the association between CT-measured abdominal fat areas and kidney function before and after donor nephrectomy. Donors underwent glomerular filtration rate measurements (125I-Iothalamate, mGFR) before and 3 months after donation. Linear regression analyses with body surface area (BSA)-standardized and crude mGFR were performed to assess the association of height-indexed tomographic fat measurements with kidney function. In age-, and sex-adjusted analyses higher levels of total abdominal, visceral, subcutaneous, and intramuscular adipose tissue index were significantly associated with lower mGFR levels before donation (BSA-standardized mGFR: visceral adipose tissue index: Βeta=-0.11, p < 0.001, subcutaneous: Βeta=-0.10, p < 0.001, intramuscular: Βeta=-1.18, p < 0.001, total abdominal: Βeta=-0.07, p < 0.001). Higher tomographic abdominal fat is associated with lower BSA-standardized mGFR after donation and a greater decrease in mGFR between screening and 3 months post-donation. This study shows that CT-measured abdominal fat area is associated with kidney function before and after living kidney donation.

Physiological confounders of renal blood flow measurement

OBJECTIVES

Renal blood flow (RBF) is controlled by a number of physiological factors that can contribute to the variability of its measurement. The purpose of this review is to assess the changes in RBF in response to a wide range of physiological confounders and derive practical recommendations on patient preparation and interpretation of RBF measurements with MRI.

METHODS

A comprehensive search was conducted to include articles reporting on physiological variations of renal perfusion, blood and/or plasma flow in healthy humans.

RESULTS

A total of 24 potential confounders were identified from the literature search and categorized into non-modifiable and modifiable factors. The non-modifiable factors include variables related to the demographics of a population (e.g. age, sex, and race) which cannot be manipulated but should be considered when interpreting RBF values between subjects. The modifiable factors include different activities (e.g. food/fluid intake, exercise training and medication use) that can be standardized in the study design. For each of the modifiable factors, evidence-based recommendations are provided to control for them in an RBF-measurement.

CONCLUSION

Future studies aiming to measure RBF are encouraged to follow a rigorous study design, that takes into account these recommendations for controlling the factors that can influence RBF results.

Association between the cardiometabolic index and chronic kidney disease: a cross-sectional study

BACKGROUND

Central obesity is a risk factor for chronic kidney disease (CKD). However, the exact correlation between the cardiometabolic index (CMI), an indicator of central obesity, and CKD remains unclear. Here, we aimed to investigate the correlation between the CMI and CKD in the general American population.

METHODS

This cross-sectional study involved 64,313 members of the general population (≥ 20 years of age) with data in the National Health and Nutrition Examination Survey (NHANES) 1999-2020. The individuals were grouped into three categories by CMI tertile: T1 group (n = 7,029), T2 group (n = 7,356), and T3 group (n = 7,380). Logistic regression analysis was performed, with NHANES recommended weights, to assess the association between the CMI and CKD.

RESULTS

A total of 21,765 participants were included; the overall prevalence of CKD was 12.2%. From the low to the high CMI tertile, the prevalence of CKD increased from 8.9% to 16.0% (P < 0.001). After full adjustment for confounders, the higher tertile of CMI (OR: 1.08, 95% CI: 1.03 - 1.13, P = 0.002) had the higher risk of CKD. Compared with the T1 group, the groups with higher CMI levels had a higher CKD risk (T2: OR: 1.01, 95%CI: 0.87-1.18, P = 0.812; T3: OR: 1.22, 95%CI: 1.05-1.43, P = 0.013).

CONCLUSIONS

Higher CMI was independently associated with higher CKD risk in the general population.

Central Body Fat Distribution and Kidney Function after Living Kidney Donation

BACKGROUND

In most screening guidelines, high body mass index (BMI) is considered a contraindication for kidney donation. New insights suggest that central body fat distribution might provide greater power in assessing kidney risk. This study aimed to determine whether BMI and central body fat distribution measures are associated with long-term kidney function after donor nephrectomy. We hypothesized that higher BMI, waist circumference (WC), and waist-to-height ratio (WHtR) were associated with lower kidney function long term after donation.

METHODS

The study population consisted of living kidney donors. BMI, WC, and WHtR were measured during donor screening. The outcome postdonation kidney function was assessed using measured GFR (mGFR) (mGFR, 125 I-iothalamate infusion) at 3 months ( n =1042), 5 years ( n =556), and 10 years ( n =210) of follow-up. Primary multivariable linear regression analyses were performed with BMI and WC and secondary analyses with WHtR. Linear mixed models were performed to investigate change in postdonation eGFR.

RESULTS

The donor age was 52±11 years, and 48% were male. The mean BMI was 26.1±3.6 kg/m 2 , and WC was 91±11 cm. Higher predonation BMI was associated with lower mGFR throughout follow-up: -1.35 (95% confidence interval [CI], -1.95 to -0.80), -1.55 (95% CI, -2.50 to -0.65), and -2.35 (95% CI, -4.10 to -0.60) ml/min per m 2 per 5 kg/m 2 higher BMI at 3 months, 5, and 10 years after donation, respectively, adjusted for sex, age, and predonation GFR. For WC, differences in mGFR were -1.30 (95% CI, -1.70 to -0.90), -1.50 (95% CI, -2.20 to -0.80), and -1.70 (95% CI, -3.00 to -0.50) ml/min per m 2 per 10 cm higher WC at 3 months, 5, and 10 years after donation, respectively. In male donors, BMI and WC were significantly associated with a negative postdonation change in eGFR.

CONCLUSIONS

Higher BMI and WC were independently associated with lower GFR (long term) after living kidney donation.

Excess body weight, duration of insulin and antihypertensive therapy slow down the rate of progression of chronic kidney disease in type 2 diabetes

Objective: to study and clinically substantiate the relationship between overweight and the dynamics of CKD progression in patients with type 2 diabetes of different age groups using the diagnostic parameter Index of glomerular filtration rate reduction. Material and methods: a single-stage cross-sectional observational study of clinical indicators in a population sample of patients with type 2 diabetes of different age groups was performed, patterns of relationships, significance of differences in mean values and measures of influence (OR (95%CI)) were studied between the indicators of BMI, the stage of obesity and the presence of a diagnosis of obesity in the anamnesis and the original calculated diagnostic parameter, the Index of glomerular filtration rate reduction (RI_GFR), which allows to give an objective quantitative characteristic of the rate of progression of CKD. Results: significant correlations were established between RI_GFR and indicators of age, BMI, DM experience and duration of insulin therapy, a significant inverse relationship with BMI was noted only in the older group; when analyzing differences in the average values of clinical indicators in the groups of rapid and slow progression of CKD, divided by the threshold value of RI_GFR, significant factors affecting the rate of progression were determined CKD: DM experience, duration of insulin therapy, BMI; the logistic regression analysis determined the measure of the influence of the above factors on the dynamics of GFR reduction, confirmed its significance; when analyzing the factors of drug treatment in the elderly group, it was revealed that an integrated approach to the appointment of antihypertensive therapy (prescribing drugs of three or more groups) significantly reduces the risk of rapid progression of CKD. Conclusions: the most significant risk factors for the high rate of progression of CKD in patients with type 2 diabetes and overweight in the general sample and in patients of the older age group are the length of diabetes and duration of insulin therapy; the dynamics of GFR reduction in patients with type 2 diabetes of different age groups is interrelated with BMI, and in patients with overweight CKD progresses more slowly; an integrated approach to prescribing antihypertensive therapy (prescribing drugs of three or more groups) in elderly patients with type 2 diabetes significantly reduces the risk of rapid progression of CKD.

Abdominal adipose tissue and type 2 diabetic kidney disease: adipose radiology assessment, impact, and mechanisms

Diabetic kidney disease (DKD) is a significant healthcare burden worldwide that substantially increases the risk of kidney failure and cardiovascular events. To reduce the prevalence of DKD, extensive research is being conducted to determine the risk factors and consequently implement early interventions. Patients with type 2 diabetes mellitus (T2DM) are more likely to be obese. Abdominal adiposity is associated with a greater risk of kidney damage than general obesity. Abdominal adipose tissue can be divided into different fat depots according to the location and function, including visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), perirenal adipose tissue (PAT), and renal sinus adipose tissue (RSAT), which can be accurately measured by radiology techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI). Abdominal fat depots may affect the development of DKD through different mechanisms, and radiologic abdominal adipose characteristics may serve as imaging indicators of DKD risk. This review will first describe the CT/MRI-based assessment of abdominal adipose depots and subsequently describe the current studies on abdominal adipose tissue and DKD development, as well as the underlying mechanisms in patients of T2DM with DKD.

Risk Factors of Chronic Kidney Disease Progression: Between Old and New Concepts

Chronic kidney disease (CKD) is a condition characterized by the gradual loss of kidney function over time and it is a worldwide health issue. The estimated frequency of CKD is 10% of the world's population, but it varies greatly on a global scale. In absolute terms, the staggering number of subjects affected by various degrees of CKD is 850,000,000, and 85% of them are in low- to middle-income countries. The most important risk factors for chronic kidney disease are age, arterial hypertension, diabetes, obesity, proteinuria, dyslipidemia, and environmental risk factors such as dietary salt intake and a more recently investigated agent: pollution. In this narrative review, we will focus by choice just on some risk factors such as age, which is the most important non-modifiable risk factor, and among modifiable risk factors, we will focus on hypertension, salt intake, obesity, and sympathetic overactivity.

Sex-specific association of body mass index and fatty liver index with prevalence of renal hyperfiltration: a cross sectional study using Japanese health check-up data

BACKGROUND

The relationship between obesity and nonalcoholic fatty liver disease and renal hyperfiltration is controversial. This study aimed to assess the correlations of body mass index and fatty liver index, respectively, with renal hyperfiltration in non-diabetic subjects, considering age, sex, and body surface area.

METHODS

This cross-sectional study assessed the Japanese health check-up data (FY2018) of 62,379 non-diabetic individuals from a health insurance database. Renal hyperfiltration is the ≥ 95th percentile of estimated glomerular filtration rate (derived by Chronic Kidney Disease Epidemiology Collaboration formula) by gender and age in healthy subjects. After adjusting for potential confounders, multiple logistic regression models were applied to evaluate the correlation of renal hyperfiltration with body mass index categories and fatty liver index (10 equal parts).

RESULTS

A negative and positive correlation, respectively, were noted when the body mass index was < 21 and ≥ 30 in women; however, a positive correlation was noted for BMI < 18.5 and ≥ 30 in men. Renal hyperfiltration prevalence increased when fatty liver index increased for both sexes; the cutoff value for fatty liver index was 14.7 for women and 30.4 for men.

CONCLUSIONS

Body mass index and renal hyperfiltration correlated linearly in women; however, in men, the correlation was U-shaped; therefore, differing by sex. However, fatty liver index correlated linearly with renal hyperfiltration in both sexes. Non-alcoholic fatty liver disease might be associated with renal hyperfiltration; Fatty liver index is a simple marker that can be obtained from health check-ups. Since a high fatty liver index correlated with renal hyperfiltration, it may be beneficial to monitor the renal function in such a population.

Association of intraabdominal fat with the risk of incident chronic kidney disease according to body mass index among Korean adults

BACKGROUND

The association between abdominal visceral adipose tissue and the risk of incident chronic kidney disease according to body mass index in the Asian population, remains unclear. We evaluated the impact of abdominal adiposity stratified by body mass index on the risk of incident chronic kidney disease.

METHODS

A cohort study included 11,050 adult participants who underwent health check-ups and re-evaluated the follow-up medical examination at a single university-affiliated healthcare center. Cross-sectional abdominal adipose tissue areas were measured using computed tomography. The primary outcome was progression to chronic kidney disease (estimated glomerular filtration rate <60 ml/min/1.73m2). The highest quartile of visceral adipose tissue was used for the cut-off of central obesity.

RESULTS

During the mean of 5.6 follow-up years, 104 incident chronic kidney disease cases were identified. The risk for chronic kidney disease incidence was significantly increased in the 3rd and 4th quartile ranges of visceral adipose tissue [hazard ratio (95% confidence interval)]: 4.59 (1.48-14.30) and 7.50 (2.33-24.20), respectively. In the analysis stratified by body mass index, the chronic kidney disease incidence risk was increased in the highest quartile range of visceral adipose tissue in the normal weight group: 7.06 (1.35-37.04). However, there was no significant relationship between visceral adipose tissue and chronic kidney disease in the obese group. Compared to the subjects with normal weight and absent central obesity, the hazard ratio for chronic kidney disease incidence was 2.32 (1.26-4.27) among subjects with normal weight and central obesity and 1.81 (1.03-3.15) among subjects with obesity and central obesity.

CONCLUSION

Visceral adipose tissue was a significant risk factor for subsequent chronic kidney disease progression, and the association was identified only in the normal weight group. Normal-weight central obesity was associated with excess risk of chronic kidney disease, similar to the risk in the group with obesity and central obesity.

Association between trunk-to-peripheral fat ratio and renal function in elderly Japanese men: baseline data from the Fujiwara-kyo Osteoporosis Risk in Men (FORMEN) study

BACKGROUND

Central obesity as measured by waist-to-hip circumference ratio (WHR) has been reported to be associated with renal hemodynamics and function. However, the adipose component of WHR, which is a composite measure of fat mass and fat-free mass, is small, particularly in nonobese subjects. Trunk-to-peripheral fat ratio as measured using dual-energy absorptiometry (DXA) is a more precise method for evaluating central fat distribution than WHR. The present study investigated the cross-sectional association between DXA-measured trunk-to-peripheral fat ratio and estimated glomerular filtration rate (eGFR) in community-dwelling elderly Japanese men.

METHODS

Participants were 575 men aged ≥65 years at the time of the baseline survey of the second Fujiwara-kyo Osteoporosis Risk in Men (FORMEN) cohort study. Trunk-to-appendicular fat ratio (TAR) was calculated as trunk fat divided by appendicular fat (sum of arm and leg fat), and trunk-to-leg fat ratio (TLR) as trunk fat divided by leg fat.

RESULTS

eGFR values significantly decreased from the lowest to the highest quintile of TAR/TLR. After adjusting for potential confounding factors including whole-body fat, the highest quintile of both TAR and TLR showed statistically significant odds ratios for the risk of eGFR <60 ml/min/1.73 m², relative to the lowest quintile. In addition, a significant decreasing trend was observed for eGFR values from the lowest to the highest quintile of TAR/TLR after adjusting for confounding factors including whole-body fat.

CONCLUSION

Elderly men with a large trunk-to-peripheral fat ratio tended to have a lower eGFR. This association occurred independently of that between whole-body fat and eGFR.

Lipidomic profiling in the Strong Heart Study identified American Indians at risk of chronic kidney disease

Dyslipidemia associates with and usually precedes the onset of chronic kidney disease (CKD), but a comprehensive assessment of molecular lipid species associated with risk of CKD is lacking. Here, we sought to identify fasting plasma lipids associated with risk of CKD among American Indians in the Strong Heart Family Study, a large-scale community-dwelling of individuals, followed by replication in Mexican Americans from the San Antonio Family Heart Study and Caucasians from the Australian Diabetes, Obesity and Lifestyle Study. We also performed repeated measurement analysis to examine the temporal relationship between the change in the lipidome and change in kidney function between baseline and follow-up of about five years apart. Network analysis was conducted to identify differential lipid classes associated with risk of CKD. In the discovery cohort, we found that higher baseline level of multiple lipid species, including glycerophospholipids, glycerolipids and sphingolipids, was significantly associated with increased risk of CKD, independent of age, sex, body mass index, diabetes and hypertension. Many lipid species were replicated in at least one external cohort at the individual lipid species and/or the class level. Longitudinal change in the plasma lipidome was significantly associated with change in the estimated glomerular filtration rate after adjusting for covariates, baseline lipids and the baseline rate. Network analysis identified distinct lipidomic signatures differentiating high from low-risk groups. Thus, our results demonstrated that disturbed lipid metabolism precedes the onset of CKD. These findings shed light on the mechanisms linking dyslipidemia to CKD and provide potential novel biomarkers for identifying individuals with early impaired kidney function at preclinical stages.

Obesity-related glomerulopathy: Current approaches and future perspectives

Obesity-related glomerulopathy (ORG) is a silent comorbidity which is increasing in incidence as the obesity epidemic escalates. ORG is associated with serious health consequences including chronic kidney disease, end-stage renal disease (ESRD), and increased mortality. Although the pathogenic mechanisms involved in the development of ORG are not fully understood, glomerular hemodynamic changes, renin-angiotensin-aldosterone system (RAAS) overactivation, insulin-resistance, inflammation and ectopic lipid accumulation seem to play a major role. Despite albuminuria being commonly used for the non-invasive evaluation of ORG, promising biomarkers of early kidney injury that are emerging, as well as new approaches with proteomics and metabolomics, might permit an earlier diagnosis of this disease. In addition, the assessment of ectopic kidney fat by renal imaging could be a useful tool to detect and evaluate the progression of ORG. Weight loss interventions appear to be effective in ORG, although large-scale trials are needed. RAAS blockade has a renoprotective effect in patients with ORG, but even so, a significant proportion of patients with ORG will eventually progress to ESRD despite therapeutic efforts. It is noteworthy that certain antidiabetic agents such as sodium-glucose cotransporter 2 inhibitors (SGLT2i) or glucagon-like peptide-1 receptor agonists (GLP-1 RAs) could be useful in the treatment of ORG through different pleiotropic effects. In this article, we review current approaches and future perspectives in the care and treatment of ORG.

Prognostic Value of Arm Circumference for Cardiac Damage and Major Adverse Cardiovascular Events: A Friend or a Foe? A 2-Year Follow-Up in the Northern Shanghai Study

Background

The high prevalence of cardiovascular diseases globally causes a great social burden and much individual suffering. The effective recognition of high-risk subjects is critical for primary prevention in the general population. In the elderly cohort, anthropometric measurements may have different prognostic values. Our study aimed to find convincing anthropometric measures to supplement conventional risk factors for major adverse cardiovascular events (MACEs) in the elderly cohort.

Materials and Methods

A total of 1,576 elderly participants (44.5% male, aged 72.0 ± 6.0 years) recruited into the Northern Shanghai Study (2014–2015) were followed up between 2016 and 2017. Following the standard guideline for cardiovascular risk evaluation, all conventional cardiovascular risk factors were assessed. The body measures were made up of body weight, body height, hip circumference, waist circumference, and middle-upper arm circumference (MUAC). Organ damage (OD) markers for cardiac, vascular, and renal diseases will be evaluated by the standardized methods.

Results

After the average 571 (±135) days of follow-up, a total of 90 MACEs (5.7%) occurred, i.e., 13 non-fatal myocardial infarction, 68 non-fatal stroke, and 9 cardiovascular deaths. Univariable COX survival analysis revealed that only MUAC could validly predict MACEs among anthropometric characters [adjusted hazard ratio (HR) 0.89; 95% confidence interval (CI) 0.82–0.96]. In Kaplan-Meier analysis, the group of high MUAC showed the lowest MACE risk (log-rank p = 0.01). Based on OD analysis, MUAC was independently linked to higher risk of left ventricular hypertrophy (LVH) in women and left ventricular diastolic dysfunction (LVDD) in both men and women. In adjusted COX analysis, only MUAC indicated statistical significance, but all other anthropometric parameters such as BMI, waist circumference, and waist-to-hip ratio (WHR) did not indicate significance. The higher level of MUAC remained a protective factor in fully adjusted models (HR: 0.73; 95% CI: 0.59–0.91), with p-values markedly significant in men (HR: 0.69; 95% CI: 0.49–0.97) and marginally significant in women (HR: 0.0.77; 95% CI: 0.59–1.01). After considering all factors (i.e., cardiovascular risk factors, MUAC, BMI, and WHR), the fully adjusted COX regression analysis demonstrated that the increased MUAC level was linked to decreased MACE risk in both men (HR: 0.57; 95% CI: 0.37–0.88) and women (aHR: 0.64; 95% CI: 0.46–0.93).

Conclusion

Despite being associated with a higher rate of cardiac damage, higher MUAC independently and significantly conferred protection against the MACE, in the elderly cohort.

Repository Describing the Anatomical, Physiological, and Biological Changes in an Obese Population to Inform Physiologically Based Pharmacokinetic Models

Background

Obesity is associated with physiological changes that can affect drug pharmacokinetics. Obese individuals are underrepresented in clinical trials, leading to a lack of evidence-based dosing recommendations for many drugs. Physiologically based pharmacokinetic (PBPK) modelling can overcome this limitation but necessitates a detailed description of the population characteristics under investigation.

Objective

The purpose of this study was to develop and verify a repository of the current anatomical, physiological, and biological data of obese individuals, including population variability, to inform a PBPK framework.

Methods

A systematic literature search was performed to collate anatomical, physiological, and biological parameters for obese individuals. Multiple regression analyses were used to derive mathematical equations describing the continuous effect of body mass index (BMI) within the range 18.5–60 kg/m² on system parameters.

Results

In total, 209 studies were included in the database. The literature reported mostly BMI-related changes in organ weight, whereas data on blood flow and biological parameters (i.e. enzyme abundance) were sparse, and hence physiologically plausible assumptions were made when needed. The developed obese population was implemented in Matlab^® and the predicted system parameters obtained from 1000 virtual individuals were in agreement with observed data from an independent validation obese population. Our analysis indicates that a threefold increase in BMI, from 20 to 60 kg/m², leads to an increase in cardiac output (50%), liver weight (100%), kidney weight (60%), both the kidney and liver absolute blood flows (50%), and in total adipose blood flow (160%).

Conclusion

The developed repository provides an updated description of a population with a BMI from 18.5 to 60 kg/m² using continuous physiological changes and their variability for each system parameter. It is a tool that can be implemented in PBPK models to simulate drug pharmacokinetics in obese individuals.

Magnitude of Drug–Drug Interactions in Special Populations

Drug–drug interactions (DDIs) are one of the most frequent causes of adverse drug reactions or loss of treatment efficacy. The risk of DDIs increases with polypharmacy and is therefore of particular concern in individuals likely to present comorbidities (i.e., elderly or obese individuals). These special populations, and the population of pregnant women, are characterized by physiological changes that can impact drug pharmacokinetics and consequently the magnitude of DDIs. This review compiles existing DDI studies in elderly, obese, and pregnant populations that include a control group without the condition of interest. The impact of physiological changes on the magnitude of DDIs was then analyzed by comparing the exposure of a medication in presence and absence of an interacting drug for the special population relative to the control population. Aging does not alter the magnitude of DDIs as the related physiological changes impact the victim and perpetrator drugs to a similar extent, regardless of their elimination pathway. Conversely, the magnitude of DDIs can be changed in obese individuals or pregnant women, as these conditions impact drugs to different extents depending on their metabolic pathway.

Is lipid accumulation product a better cardiovascular risk predictor in elderly individuals than anthropometric measures?

INTRODUCTION

Population aging is associated with increased prevalence of cardiovascular diseases that have a significant impact on overall morbidity and mortality. Insulin resistance (IR) and visceral obesity are risk factors for vascular damage and cardiometabolic diseases.

AIMS

Estimating the correlation between lipid accumulation product (LAP) and IR in elderly individuals and comparing them to traditional anthropometric indices.

METHODS

Cross-sectional study comprising 411 individuals >60 years, who were treated in a primary care service. Body mass index (BMI), neck circumference (NC), waist circumference (WC), hip circumference (HC), arm circumference (AC), sagittal abdominal diameter (SAD) and waist-hip ratio (WHR) were recorded. IR was estimated based on HOMA-IR (homeostasis model assessment IR index). LAP^a index was calculated as [WC-65]×[triglyceride (TG)] in men, and as [WC-58]×[TG] in women, whereas LAP^b was calculated by using the minimum WC values recorded for the current sample, i.e., 61.5 cm for women and 71.5 cm for men.

RESULTS

There was correlation among LAP^a (0.506), LAP^b (0.515) and HOMA-IR. LAP was better correlated to HOMA-IR and showed higher area under the curve than BMI, NC, WHR and SAD. Based on the receiver operating characteristic curve analysis, LAP^b≥47.40 and LAP^a≥52.5 were the best cut-off values used to identify individuals with IR presenting 68.8% and 68.2% sensitivity, and 68.6% and 68.6% specificity, respectively.

CONCLUSION

LAP may be a useful and simple clinical marker to assess cardiometabolic risk factors in the elderly population treated at a primary care service.

Is lipid accumulation product a better cardiovascular risk predictor in elderly individuals than anthropometric measures?

INTRODUCTION

Population aging is associated with increased prevalence of cardiovascular diseases that have a significant impact on overall morbidity and mortality. Insulin resistance (IR) and visceral obesity are risk factors for vascular damage and cardiometabolic diseases.

AIMS

Estimating the correlation between lipid accumulation product (LAP) and IR in elderly individuals and comparing them to traditional anthropometric indices.

METHODS

Cross-sectional study comprising 411 individuals >60 years, who were treated in a primary care service. Body mass index (BMI), neck circumference (NC), waist circumference (WC), hip circumference (HC), arm circumference (AC), sagittal abdominal diameter (SAD) and waist-hip ratio (WHR) were recorded. IR was estimated based on HOMA-IR (homeostasis model assessment IR index). LAP^a index was calculated as [WC-65]×[triglyceride (TG)] in men, and as [WC-58]×[TG] in women, whereas LAP^b was calculated by using the minimum WC values recorded for the current sample, i.e., 61.5 cm for women and 71.5 cm for men.

RESULTS

There was correlation among LAP^a (0.506), LAP^b (0.515) and HOMA-IR. LAP was better correlated to HOMA-IR and showed higher area under the curve than BMI, NC, WHR and SAD. Based on the receiver operating characteristic curve analysis, LAP^b≥47.40 and LAP^a≥52.5 were the best cut-off values used to identify individuals with IR presenting 68.8% and 68.2% sensitivity, and 68.6% and 68.6% specificity, respectively.

CONCLUSION

LAP may be a useful and simple clinical marker to assess cardiometabolic risk factors in the elderly population treated at a primary care service.

Hypertriglyceridemic waist phenotype and risk of chronic kidney disease in community-dwelling adults aged 60 years and older in Tianjin, China: a 7-year cohort study

Background

The hypertriglyceridemic waist (HTGW) phenotype has been proposed to be related to the occurrence and progression of chronic kidney disease (CKD). The ageing trend of the Chinese population continues to intensify, and elderly individuals are at high risk of CKD. The purpose of this study was to investigate the cross-sectional and longitudinal associations between the HTGW phenotype and the risk of CKD by following community-dwelling adults aged 60 years and older in Tianjin, China, for 7 years.

Methods

This study was an observational cohort study conducted between 2013 and 2019. Of 2050 participants aged 60 years and older who underwent an annual health examination in 2013, 1605 individuals with complete data were enrolled in the cross-sectional analysis. Among them, 1271 individuals were observed until 2019. Detailed follow-up records were available for 816 participants, of whom 600 participants without CKD at baseline were eligible for inclusion in the retrospective analysis. The HTGW phenotype was defined as a waist circumference of 90 cm or more and triglyceride concentrations of 2.0 mmol/L or more in males or a waist circumference of 85 cm or more and triglyceride concentrations of 1.5 mmol/L or more in females. CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73m² and/or proteinuria (urinary albumin-to-creatinine ratio (ACR) ≥ 30 mg/g). Multivariable logistic regression analyses were performed to evaluate the relationship between the HTGW phenotype and CKD.

Results

In 2013, the prevalence of CKD among older adults was 31.03%, and the prevalence of CKD in the HTGW phenotype group was 37.81%. Over a 7-year observation period, 195 individuals developed CKD, with an incidence rate of 32.50%. Statistically significant associations were observed between the HTGW phenotype and CKD in older adults in both cross-sectional surveys and retrospective analyses, with odds ratios and 95% confidence intervals of 1.38 (95% CI: 1.03–1.86, P = 0.033) and 2.27 (95% CI: 1.30–3.97, P = 0.004), respectively, after adjustment for confounders.

Conclusions

In this community-based cohort study, the HTGW phenotype was confirmed to be independently associated with an increased risk of prevalent and incident CKD in older adults aged 60 years and above in Tianjin, China.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02339-5.

Comparison of eGFR formulas in determining chronic kidney disease stage in bariatric patients and the impact on perioperative outcomes

BACKGROUND

Chronic kidney disease (CKD) independently increases the risk of 30-day adverse outcomes following metabolic and bariatric surgery (MBS). However, no studies have evaluated the stage of CKD at which increased perioperative risk is manifested. Here, we correlate 30-day major morbidities after MBS with extent of renal disease based on CKD Stage.

OBJECTIVES

To determine the impact of CKD stage on perioperative outcomes after bariatric surgery.

SETTING

Academic Hospital.

METHODS

From the 2017 Metabolic and Bariatric Surgery Quality Improvement Program (MBSAQIP) database, we identified patients with CKD who underwent sleeve gastrectomy or laparoscopic gastric bypass surgery. Glomerular filtration rates (GFRs) were calculated and cohorts were generated based on CKD Stage. Complication rates and rates of morbidity and mortality were compared between stages, and strengths of correlation were calculated.

RESULTS

GFR and CKD Stage were calculated for 150,283 patients. There was a significant increase in the risk of major morbidity at each progressive stage of CKD (P < .001 for all compared stages). There was a strong positive linear correlation between increasing CKD Stage and total morbidity (r² = .983), including reoperation ( r² = .784), readmission (r² = .936), unplanned ICU transfer (r² = .853), and aggregate complications such as pulmonary (r² = .900), bleeding (r² = .878), or progressive worsening of renal function (r² = .845). In logistic regression, for every 10-point decrease in GFR, odds of total morbidity increased by 6%.

CONCLUSION

An increased risk of perioperative complications may be seen in early stages of CKD, and risk is compounded in more advanced stages. Bariatric surgical candidates should be counseled on their increased risk of surgical complications even with mild CKD, and the benefits of bariatric surgery should be carefully weighed against significantly increased risks of complications in severe CKD.

Association of hypertriglyceridemic waist phenotype with renal function impairment: a cross-sectional study in a population of Chinese adults

Background

Hypertriglyceridemic waist (HTGW) phenotype has been suggested as a risk factor for chronic kidney disease (CKD). However, there is limited evidence on the relationship of triglyceride waist phenotypes with estimated glomerular filtration rate (eGFR) status and severity. Our aim was to explore the associations of triglyceride waist phenotypes with reduced eGFR and various decreased eGFR stages among Chinese adults.

Methods

A population-based, cross-sectional study was conducted among Chinese participants aged 20–74 years from June 2016 to December 2017 in Shanghai, China. An eGFR value below 60 mL/min/1.73 m² was defined as decreased eGFR. HTGW phenotype was defined as triglyceride (TG) ≥1.7 mmol/L and a waist circumference (WC) of ≥90 cm for men and ≥ 80 cm for women. We examined the association of triglyceride waist phenotypes with decreased eGFR risk using the weighted logistic regression models.

Results

A total of 31,296 adults were included in this study. Compared with normal TG level/normal WC (NTNW) phenotype, normal TG level/enlarged WC (NTGW) and elevated TG level/enlarged WC (HTGW) phenotypes were associated with the increased risk of decreased eGFR. Multivariable-adjusted ORs (95% CI) associated with NTGW, elevated TG level/normal WC (HTNW), and HTGW phenotypes were 1.75 (1.41–2.18), 1.29 (0.99–1.68), and 1.99 (1.54–2.58), respectively. These associations between triglyceride waist phenotypes and decreased eGFR risk remained across almost all the subgroups, including sex, age, BMI, T2DM, and hypertension. HTGW phenotype was consistently positively associated with the risk of mildly and moderately decreased eGFR, but not with severely decreased eGFR risk.

Conclusions

HTGW was consistently associated with the increased risk of decreased eGFR and various decreased eGFR stages, except for severely decreased eGFR. Further prospective studies are warranted to confirm our findings and to investigate the underlying biological mechanisms.

Altered renal hemodynamics is associated with glomerular lipid accumulation in obese Dahl salt-sensitive leptin receptor mutant rats

The present study examined whether development of renal injury in the nondiabetic obese Dahl salt-sensitive leptin receptor mutant (SS^LepRmutant) strain is associated with elevations in glomerular filtration rate and renal lipid accumulation. Baseline mean arterial pressure at 6 wk of age was similar between Dahl salt-sensitive wild-type (SS_WT) and SS^LepRmutant rats. However, by 18 wk of age, the SS^LepRmutant strain developed hypertension, while the elevation in mean arterial pressure was not as severe in SS_WT rats (192 ± 4 and 149 ± 6 mmHg, respectively). At baseline, proteinuria was fourfold higher in SS^LepRmutant than SS_WT rats and remained elevated throughout the study. The early development of progressive proteinuria was associated with renal hyperfiltration followed by a decline in renal function over the course of study in the SS^LepRmutant compared with SS_WT rats. Kidneys from the SS^LepRmutant strain displayed more glomerulosclerosis and glomerular lipid accumulation than SS_WT rats. Glomeruli were isolated from the renal cortex of both strains at 6 and 18 wk of age, and RNA sequencing was performed to identify genes and pathways driving glomerular injury. We observed significant increases in expression of the influx lipid transporters, chemokine (C-X-C motif) ligand 16 (Cxcl16) and scavenger receptor and fatty acid translocase (Cd36), respectively, and a significant decrease in expression of the efflux lipid transporter, ATP-binding cassette subfamily A member 2 (Abca2; cholesterol efflux regulatory protein 2), in SS^LepRmutant compared with SS_WT rats at 6 and 18 wk of age, which were validated by RT-PCR analysis. These data suggest an association between glomerular hyperfiltration and glomerular lipid accumulation during the early development of proteinuria associated with obesity.

Individual and Combined Components of Metabolic Syndrome with Chronic Kidney Disease in Individuals with Hypertension and/or Diabetes Mellitus Accompanied by Primary Health Care

PURPOSE

To identify the associations between MetS and its components and chronic kidney disease (CKD) in a population with arterial hypertension (AH), or diabetes mellitus (DM) accompanied by the Primary Health Care (PHC).

PATIENTS AND METHODS

A cross-sectional study with 788 individuals diagnosed with AH and/or DM followed by PHC of Viçosa, Brazil. Anthropometric, biochemical and clinical measures were performed for the diagnosis of MetS and CKD. MetS was identified using the NCEP-ATPIII criteria. CKD was identified by estimating the glomerular filtration rate using the CKD-EPI equation. Logistic regression models were used to estimate the chances of CKD associated with MetS and its components and specific combinations of components.

RESULTS

The prevalence of MetS reported in the population was 65.4%, that of hidden CKD was 15.4%. The prevalence of CKD among participants with MetS was 75.2%. The most prevalent component of MetS in the population was AH (96.7%). Elevated fasting blood glucose, central obesity, and reduced HDL-c were significantly associated with an increased chance of CKD (OR = 2.80, 95% CI 1.76-4.45, OR = 1.68, 95% CI, 05-2.71, OR = 1.61, CI 95% 1.03-2.50, respectively). For the multivariate adjustment, the participants with MetS were 2 times more likely to have CKD than those without MetS (OR = 2.07; 95% CI, 1.25-3.44). The combination of three components of MetS high blood pressure, abdominal obesity and elevated fasting blood glucose and the combination of four components of MetS high blood pressure, reduced HDL-c, high fasting blood glucose and abdominal obesity were associated with increased odds of CKD (OR = 2.67, CI 95% 1.70-4.20, OR = 2.50, CI 95% 1.55-4.02, respectively).

CONCLUSION

MetS, as well as its individual or combined components were independently associated with CKD in the population with AH and/or DM accompanied by PHC.

Comparison of Novel Metabolic Indices in Estimation of Chronic Kidney Diseases in a Southern Chinese Population

BACKGROUND

To determine the optimal cut-off values and evaluate the associations of product of triacylglycerol and glucose (TyG), lipid accumulation product (LAPI), visceral adiposity index (VAI) with chronic kidney diseases (CKD) stratified by sex.

METHODS

From January to April 2018, our team had conducted a large-scale cross-sectional survey that contained 2720 individuals on the southern coast of China. Logistic regression analysis and receiver operating characteristic (ROC) analyses were used to evaluate the optimal cut-off and value of TyG, LAPI, VAI for predicting CKD.

RESULTS

A multivariate logistic regression analysis found that the TyG had the better value of prediction for the presence of CKD for the highest quartile vs the lowest quartile in both males (OR: 3.65; 95% CI, 2.04-6.52; p<0.001) and females (OR: 3.50; 95% CI, 2.20-5.56; p<0.001), followed by LAPI and VAI, when further adjusted for cofounder factors, LAPI and VAI both lost their independence, and only TyG remains its significant association with CKD in both males (OR: 2.81; 95% CI, 1.25-6.30; p<0.001) and females (OR: 3.22; 95% CI, 1.56-6.61; p<0.001). ROC curve showed that TyG had the highest AUC for predicting CKD in males (AUC: 0.618). TyG (AUC: 0.670) and LAPI (AUC: 0.670) both had the highest AUC in females. United predicted models which contain TyG were conducted for predicting CKD in males (AUC: 758) and females (AUC: 0.773) and results indicated that multivariate analysis of TyG and other traditional factors can impressively improve the accuracy of predictive probability for CKD.

CONCLUSION

TyG is a priority to the other two novel indices and may become valuable makers and have strong predictive power for predicting CKD, especially in females.

Identification of chronic kidney disease risk in relatively lean Southern Chinese: the hypertriglyceridemic waist phenotype vs. anthropometric indexes

PURPOSE

Assessing and comparing the ability of the hypertriglyceridemic waist (HW) phenotype and anthropometric obesity indexes to identify subjects at high risk of chronic kidney disease (CKD) in a relatively lean population in South China.

METHODS

Using data from a community-based, cross-sectional study conducted in Zhuhai City, Southern China, we examined associations between the HW phenotype, anthropometric obesity indexes, and incident CKD risk in a relatively lean population. Multiple logistic regression analyses were used to evaluate the associations.

RESULTS

The HW phenotype associated with CKD significantly in the unadjusted analysis (OR 3.53, 95% CI 1.65-7.52, P = 0.001). Further adjustment for gender, age, and other potential confounding variables had an impact on the odd ratios (OR); the OR decreased but still existed (OR 2.91, 95% 1.23-6.87, P = 0.016). The association of the HW phenotype with CKD remained significant after further adjustment for hypertension and diabetes. No significant association between the anthropometric indexes and incident CKD was found.

CONCLUSION

The HW phenotype, but not the anthropometric indexes, is associated with an elevated risk of CKD in relatively lean subjects. The HW phenotype appears to be a better predictor of CKD than the anthropometric indexes.

LEVEL OF EVIDENCE

Level V, descriptive study.

Excessive dietary lipid intake provokes an acquired form of lysosomal lipid storage disease in the kidney

Obesity and dyslipidaemia are features of the metabolic syndrome and risk factors for chronic kidney disease. The cellular mechanisms connecting metabolic syndrome with chronic kidney disease onset and progression remain largely unclear. We show that proximal tubular epithelium is a target site for lipid deposition upon overnutrition with a cholesterol-rich Western-type diet. Affected proximal tubule epithelial cells displayed giant vacuoles of lysosomal or autophagosomal origin, harbouring oxidised lipoproteins and concentric membrane layer structures (multilamellar bodies), reminiscent of lysosomal storage diseases. Additionally, lipidomic analysis revealed renal deposition of cholesterol and phospholipids, including lysosomal phospholipids. Proteomic profiles of renal multilamellar bodies were distinct from those of epidermis or lung multilamellar bodies and of cytoplasmic lipid droplets. Tubular multilamellar bodies were observed in kidney biopsies of obese hypercholesterolaemic patients, and the concentration of the phospholipidosis marker di-docosahexaenoyl (22:6)-bis(monoacylglycerol) phosphate was doubled in urine from individuals with metabolic syndrome and chronic kidney disease. The enrichment of proximal tubule epithelial cells with phospholipids and multilamellar bodies was accompanied by enhanced inflammation, fibrosis, tubular damage markers, and higher urinary electrolyte content. Concomitantly to the intralysosomal lipid storage, a renal transcriptional response was initiated to enhance lysosomal degradation and lipid synthesis. In cultured proximal tubule epithelial cells, inhibition of cholesterol efflux transport or oxysterol treatment induced effects very similar to the in vivo situation, such as multilamellar body and phospholipid amassing, and induction of damage, inflammatory, fibrotic, and lipogenic molecules. The onset of phospholipidosis in proximal tubule epithelial cells is a novel pathological trait in metabolic syndrome-related chronic kidney disease, and emphasises the importance of healthy lysosomes and nutrition for kidney well-being. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Overweight young female kidney donors have low renal functional reserve postdonation

Maintenance of adequate renal function after living kidney donation is important for donor outcome. Overweight donors, in particular, may have an increased risk for end-stage kidney disease (ESKD), and young female donors have an increased preeclampsia risk. Both of these risks may be associated with low postdonation renal functional reserve (RFR). Because we previously found that higher body mass index (BMI) was associated with lower postdonation RFR, we now studied the relationship between BMI and RFR in young female donors. RFR, the rise in glomerular filtration rate (GFR) (¹²⁵I-iothalamate clearance) during dopamine, was measured in female donors (<45 yr) before and after kidney donation. Donors who are overweight (BMI >25) and nonoverweight donors were compared by Student's t-test; the association was subsequently explored with regression analysis. We included 105 female donors [age 41 (36-44) median(IQR)] with a BMI of 25 (22-27) kg/m². Predonation GFR was 118 (17) ml/min [mean(SD)] rising to 128 (19) ml/min during dopamine; mean RFR was 10 (10) ml/min. Postdonation GFR was 76 (13) ml/min, rising to 80 (12); RFR was 4 (6) ml/min ( P < 0.001 vs. predonation). In overweight donors, RFR was fully lost after donation (1 ml/min vs. 10 ml/min predonation, P < 0.001), and BMI was inversely associated with RFR after donation, independent of confounders (standardized β 0.37, P = 0.02). Reduced RFR might associate with the risk of preeclampsia and ESKD in kidney donors. Prospective studies should explore whether RFR is related to preeclampsia and whether BMI reduction before conception is of benefit to overweight female kidney donors during and after pregnancy.

Longitudinal assessment of renal function in native kidney after bariatric surgery

The epidemic of obesity parallels that of chronic kidney disease (CKD). Obesity worsens the course of CKD, mainly defined by an abnormal glomerular filtration rate (GFR). Patients with severe obesity stages (II and III with body mass index >35 kg/m²) are eligible for bariatric surgery (BS), which is the most efficient method of achieving durable weight loss. BS may reverse glomerular hyperfiltration and albuminuria, improve adipocytokine profile, and relieve diabetes and hypertension. Obesity remission after BS might prevent the progression of renal failure in populations with morbid obesity. However, evidence for the beneficial effect of BS on renal function is scant. This lack of knowledge is mainly due to methodologic reasons, which are addressed in this review. The reversibility of hyperfiltration due to the presence of functional renal reserve hampers the interpretation of changes in true GFR after BS. This true GFR is only obtained with the renal clearance of an exogenous filtration marker. Estimation of GFR is generally provided by prediction equations, namely by modification of diet in renal diseases or by chronic kidney disease-epidemiology collaborative group. These equations are not accurate because the serum levels of both creatinine and cystatin C depend on extrarenal factors, which are modified by BS. Comparing the slopes of measured GFR according to various durations of exposure with morbid obesity would be critical in providing reliable data. Herein, we review the current knowledge on the effects of BS on kidney function; we specify the methodologic issues and particularities of the dietary management of CKD patients to propose reliable directions for future clinical research.

Adiposity Impacts Intrarenal Hemodynamic Function in Adults With Long-standing Type 1 Diabetes With and Without Diabetic Nephropathy: Results From the Canadian Study of Longevity in Type 1 Diabetes

OBJECTIVE

Central adiposity is considered to be an important cardiorenal risk factor in the general population and in type 1 diabetes. We sought to determine the relationship between central adiposity and intrarenal hemodynamic function in adults with long-standing type 1 diabetes with and without diabetic nephropathy (DN).

RESEARCH DESIGN AND METHODS

Patients with type 1 diabetes (n = 66, duration ≥50 years) and age-/sex-matched control subjects (n = 73) were studied. The cohort was stratified into 44 DN Resistors (estimated glomerular filtration rate [eGFR] >60 mL/min/1.73 m² and <30 mg/day urine albumin) and 22 patients with DN (eGFR ≤60 mL/min/1.73 m² or ≥30 mg/day urine albumin). Intrarenal hemodynamic function (glomerular filtration rate for inulin [GFR_INULIN], effective renal plasma flow for p-aminohippuric acid [ERPF_PAH]) was measured. Afferent arteriolar resistance, efferent arteriolar resistance, renal blood flow, renal vascular resistance [RVR], filtration fraction, and glomerular pressure were derived from the Gomez equations. Fat and lean mass were quantified by DXA.

RESULTS

Whereas measures of adiposity did not associate with GFR_INULIN or ERPF_PAH in healthy control subjects, trunk fat mass inversely correlated with GFR_INULIN (r = -0.46, P < 0.0001) and ERPF_PAH (r = -0.31, P = 0.01) and positively correlated with RVR (r = 0.53, P = 0.0003) in type 1 diabetes. In analyses stratified by DN status, greater central adiposity related to lower GFR_INULIN values in DN and DN Resistors, but the relationships between central adiposity and ERPF_PAH and RVR were attenuated and/or reversed in patients with DN compared with DN Resistors.

CONCLUSIONS

The adiposity-intrarenal hemodynamic function relationship may be modified by the presence of type 1 diabetes and DN, requiring further study of the mechanisms by which adiposity influences renal hemodynamic function.

Comparison of Body Composition Metrics for United States Air Force Airmen

Background

The United States Air Force currently uses AFI 36-2905 for cardiovascular fitness standards and evaluation. Regarding its fitness test, the Air Force considers waist circumference (WC) twice as important as push-ups or sit-ups. Because of this weighting, one assumes that the Air Force considers WC relatively correlated with overall fitness or at least cardiovascular fitness. To our knowledge, the Air Force has not considered on a large scale how body mass index (BMI), height-to-weight ratio (H-W), or waist-to-height ratio (WHtR) compares with WC with respect to its fitness test.

Methods

Using a 5.38 million record database from the Air Force Fitness Management System, we evaluated how WC, BMI, WHtR, and H-W correlate with fitness as assessed by the 1.5-mile run in addition to total fitness, which incorporates the 1.5-mile run time, number of push-ups and sit-ups. As this previously collected data were anonymous to us, this study fell under the definition of exempt status and approved by the institutional review board overseeing Joint Base San Antonio. For each waist metric, we performed a simple ordinary least squares regression to ascertain the correlation between that particular metric and either run time or total fitness; when incorporating more than one explanatory variable or covariate (to control for age and/or sex), we performed multiple ordinary least squares regressions. Due to the large database size and to mitigate against a type I error, we used an alpha of 0.001 for all statistical hypothesis tests.

Findings

Approximately 18% of the 5.38 million records belonged to women. With respect to sex differences, males appeared noticeably faster and performed more push-ups on average than females. The number of sit-ups completed was more comparable, with males having a slight advantage. Males also appeared to have larger WC, BMI, H-W, and WHtR measurements. We compared the ordinary least squares results between WC, H-W, WHtR, and BMI and ranked them by R2. Models varied in R2 from 1% to 46% depending on the covariates in the model, with sex having a greater effect than age. Whether individually or adjusting for age and sex, WHtR performed better than the other body composition variables with an average rank score of 1.1 and a median improvement of approximately 4% to the current Air Force metric of WC.

Discussion

From our findings, we present a 20-point WHtR scoring system for the Air Force to use in lieu of its traditional usage of WC. We used this assessment chart to score all Airmen in our database and compared the results to their current scores on the abdominal circumference portion of the test with respect to predicting run time, after accounting for sex, age, and number of push-ups and sit-ups. The R2 value improved from 40.3 to 43.6, a relative improvement of approximately 8%, a fairly significant effect given the database consisted of over 5 million records. Future studies should investigate the longitudinal effect of varying waist metrics over time on run time or total fitness performance.

Waist Circumference and Body Mass Index in Children with Chronic Kidney Disease and Metabolic, Cardiovascular, and Renal Outcomes

OBJECTIVE

To describe the prevalence of obesity as estimated by waist circumference (WC) and body mass index (BMI) and compare associations of WC and BMI with indicators of metabolic, cardiovascular, and renal health in children with chronic kidney disease (CKD).

STUDY DESIGN

Cross-sectional analysis stratified by CKD etiology (nonglomerular or glomerular) of 737 subjects. The kappa statistic was used to assess agreement between the 2 measures of obesity. Linear regression models were performed using WC and BMI as separate independent variables. Dependent variables included lipid measures, insulin resistance, blood pressure, left ventricular mass index, proteinuria, and estimated glomerular filtration rate. Associations were scaled to SD and interpreted as the change in dependent variable associated with a 1-SD change in WC or BMI.

RESULTS

There was good agreement (kappa statistic = 0.68) between WC and BMI in identifying obesity. Approximately 10% of subjects had obesity by 1 measure but not the other. BMI was more strongly associated with estimated glomerular filtration rate than WC. BMI was more strongly associated with left ventricular mass index in the nonglomerular CKD group compared with WC, but both had significant associations. The associations between WC and BMI with the remainder of the dependent variables were not significantly different.

CONCLUSIONS

Measurement of WC added limited information to BMI in this cohort. Further longitudinal study is needed to determine how WC and BMI compare in predicting outcomes, particularly for children with CKD identified as having obesity by 1 measure but not the other.

Perirenal fat thickness measured with computed tomography is a reliable estimate of perirenal fat mass

Deposition of perirenal adipose tissue has been associated with adverse renal and cardiovascular events. We compared various methods to measure perirenal adipose tissue using computerized tomography (CT)-scan and performed correlations with anthropometric measures associated with renal and cardiovascular events. Voluntary overweight and obese subjects undergoing a CT-scan for diagnostic purposes were included in the study. Perirenal adipose tissue volume, adipose tissue area of the renal sinus and perirenal fat thickness were manually measured bilaterally. The intra- and inter-observer coefficient correlations and the correlation between the diverse measures of renal adipose tissue, subcutaneous (SC-)fat and anthropometrics measures were analyzed using Pearson's correlation tests. The forty included patients (24 men, 16 women) had a mean age of 57.6 ± 18.1 years and a mean body mass index of 28.9 ± 2.9 kg/m². Despite comparable waist circumference, women had a greater SC-fat thickness compared to men, and therefore a smaller amount of visceral fat, as well as smaller perirenal fat volumes. Perirenal fat thickness was better correlated with perirenal fat volume than adipose area of the renal sinus (p <0.02). The adipose area of the renal sinus did not correlate with any anthropometric measures. In women, perirenal fat volume and thickness showed a negative correlation with SC-fat thickness and no correlation with waist circumference. In men, perirenal fat volume and thickness showed a positive correlation with waist circumference and no correlation with subcutaneous fat thickness. In conclusion, perirenal fat thickness measured with CT-scan at the level of the renal veins is a simple and reliable estimate of perirenal fat volume, that correlated negatively with SC-fat in women and positively with waist circumference in men. The adipose area of the renal sinus did not correlate with any anthropometric measure.

The Association of Hypertriglyceridemic Waist Phenotype with Chronic Kidney Disease and Its Sex Difference: A Cross-Sectional Study in an Urban Chinese Elderly Population

Background: The primary objective of this study was to explore the association of hypertriglyceridemic waist (HTGW) phenotype with chronic kidney disease (CKD) and its sex difference in an urban Chinese elderly population. Methods: In a cross-sectional study, a total of 2102 participants aged 60-95 years were recruited and classified into four phenotypes: normal waist-normal triglyceride (NWNT), normal waist-elevated triglycerides (NWET), elevated waist-normal triglycerides (EWNT), and HTGW. Logistic regression analysis was used to estimate the associations of interest. Results: Total prevalence of CKD was 12.6%, and the CKD prevalence in participants with EWNT and HTGW was higher than with NWNT and NWET without regard to sex. Compared to NWNT phenotype, the adjusted OR for CKD was 1.95 (95% CI: 1.32-2.88) in HTGW groups. In contrast with the null findings (OR: 1.66; 95% CI: 0.94-2.94) in women after additional adjustment for diabetes and hypertension, the OR with HTGW remained strong (OR: 1.88; 95% CI: 1.04-3.39) in men. Similar findings appeared with the EWNT phenotype. Conclusions: The HTGW phenotype is positively associated with CKD among Chinese community elderly and may have a greater impact on men. More attention should be paid to the association between triglycerides and waist circumference in clinical practice and to the further identification this uncertain sex-related association.

Central obesity associates with renal hyperfiltration in the non-diabetic general population: a cross-sectional study

Background

Obesity is a risk factor for end-stage renal disease. Renal hyperfiltration, defined as an abnormally high glomerular filtration rate (GFR), is a link in the causal chain between diabetes and chronic kidney disease. Whether obesity is associated with hyperfiltration in the non-diabetic general population, remains unresolved due to a lack of consensus regarding the definition of hyperfiltration and the limited precision of high-range GFR estimations with creatinine and/or cystatin C.

Methods

1555 middle-aged participants without diabetes, renal or cardiovascular disease were enrolled from the general population in the Renal Iohexol Clearance Survey from the 6th Tromsø Study (RENIS-T6) between 2007 and 2009. Obesity was assessed using the body mass index (BMI), waist circumference (WC) and the waist-hip ratio (WHR). GFR was measured by iohexol clearance. Dichotomous variables for hyperfiltration were based on two alternative definitions using unadjusted GFR (mL/min) above the 90th percentile. The 90th percentile was age-, sex- and height-specific in one definition and age-, sex-, height- and weight-specific in the other.

Results

In multivariable adjusted logistic regression models, only WHR was consistently associated with hyperfiltration based on both definitions. For the definition based on the age-, sex-, height- and weight-specific 90th percentile, the association with the WHR (odds ratios (95 % confidence intervals)) for hyperfiltration was 1.48 (1.08–2.02) per 0.10 WHR increase.

Conclusions

Central obesity is associated with hyperfiltration in the general population. The WHR may serve as a better indicator of the renal effects of obesity than BMI or WC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-016-0386-4) contains supplementary material, which is available to authorized users.

How central obesity influences intra-abdominal pressure: a prospective, observational study in cardiothoracic surgical patients

Background

Intra-abdominal hypertension (IAH) is frequently present in critically ill patients and is an independent predictor for mortality. Better recognition of clinically important thresholds is necessary. Increased intra-abdominal pressure (IAP) is associated with renal dysfunction, and renal failure is one of the most consistently described organ dysfunctions associated with IAH. Obesity is also associated with kidney injury. The underlying mechanisms are not yet fully understood. Increased IAP may be a link in this association. The aim of this study was firstly to find the range in values of intra-abdominal pressure (IAP) in cardiothoracic surgery patients a secondly to investigate the relationship between central obesity, body mass index (BMI) and IAP and thirdly to investigate the relationship between IAP, inflammation and renal function in this population.

Methods

Consecutive adult patients admitted to the cardiothoracic unit of the intensive care unit (ICU) after undergoing elective cardiothoracic surgery were included in this prospective, observational study. C-reactive protein (CRP) as a marker of inflammation and serum creatinine as a marker of renal function were measured pre- and postoperatively. Estimated glomerular filtration rates were calculated pre- and postoperatively. BMI was calculated. Waist circumference (WC), hip circumference (HC) and transvesical IAP were measured once directly after admission to the ICU postoperatively. Waist/hip ratio (WHR) was calculated (WC divided by HC). Three definitions of central obesity were used. Central obesity was defined according to WC, WHR or median WHR.

Results

In total, 186 patients undergoing cardiothoracic surgery were included. Mean IAP was 9.1 mmHg (SD 4.4). IAP ≥ 12 mmHg was observed in 50 patients (26.9 %). IAP > 20 mmHg was measured in 4 patients (2.2 %). There was a positive correlation between IAP and BMI (r² = 0.05, p = 0.003). Correlations between IAP and WC (r² = 0.02, p = 0.054) and between IAP and WHR (r² = 0.01, p = 0.173) were not significant. There were no correlations between pre- or postoperative CRP and IAP (r² = 2.3 × 10⁻⁴, p = 0.839 and r² = 0.013, p = 0.117, respectively). In obese patients postoperative CRP was significantly higher than in non-obese patients (p = 0.034). There were no correlations between pre-operative serum creatinine and IAP (r² = 3.3 × 10⁻⁵, p = 0.938) or postoperative serum creatinine and IAP (r² = 0.003, p = 0.491).

Conclusions

The range in IAP in patients undergoing cardiothoracic surgery was wide. There was a positive correlation between IAP and BMI. Correlations between IAP and indices for central obesity were not significant. In a multiple regression model BMI was a better predictor of IAP than WHR in this population. There were no correlations between pre- or postoperative CRP and IAP. Furthermore, this study did not find evidence for a relation between IAP and pre- and postoperative serum creatinine.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-016-0195-8) contains supplementary material, which is available to authorized users.

Abdominal Obesity, Race and Chronic Kidney Disease in Young Adults: Results from NHANES 1999-2010

OBJECTIVE

Kidney dysfunction in obesity may be independent of and may precede the development of hypertension and/or diabetes mellitus. We aimed to examine if abdominal obesity is associated with early markers of CKD in a young healthy population and whether these associations differ by race and/or ethnicity.

METHODS

We analyzed data from the NHANES 1999-2010 for 6918 young adults ages 20-40 years. Abdominal obesity was defined by gender criteria of waist circumference. CKD markers included estimated glomerular filtration rate and albuminuria ≥30 mg/g. Race stratified analyses were done overall and in subgroups with normal blood pressures, normoglycemia and normal insulin sensitivity. Awareness of CKD was assessed in participants with albuminuria.

RESULTS

Abdominal obesity was present in over one-third of all young adults and was more prevalent among non-Hispanic blacks (45.4%) versus Mexican-Americans (40.6%) or non-Hispanic whites (37.4%) (P-value = 0.004). Mexican-American young adults with abdominal obesity had a higher odds of albuminuria even among those with normal blood pressure, normal glucose, and normal insulin sensitivity [adjusted odds ratio 4.5; 95% confidence interval (1.6-12.2), p = 0.004]. Less than 5% of young adults with albuminuria of all races and ethnicities had been told they had kidney disease.

CONCLUSION

Abdominal obesity in young adults, especially in Mexican-Americans, is independently associated with albuminuria even with normal blood pressures, normoglycemia and normal insulin levels. Greater awareness of CKD is needed to protect this young population from long-standing exposure to abdominal obesity and early progressive renal disease.

Lean mass modulates glomerular filtration rate in males of normal and extreme body composition

BACKGROUND

Understanding determinants of glomerular filtration rate (GFR) is important in aiding prediction and interpretation of kidney function. Body composition is known to affect GFR but is not included in current screening of kidney disease. We investigated the association between GFR and body composition in healthy young men with differing body mass but without known diabetes or kidney injury.

METHODS

Three groups were recruited: normal BMI (n = 22) with a body mass index (BMI) <25 kg/m(2) , muscular (n = 23) with BMI ≥30 kg/m(2) and bioelectrical impedance body fat ≤20% and obese (n = 22) with BMI ≥30 kg/m(2) and bioelectrical impedance body fat ≥30%. Dietary analyses, GFR clearance by (99m) Tc-DTPA, urine protein and body composition by dual-energy X-ray absorptiometry were measured in all participants. Linear and nonlinear associations of constituents of body composition with GFR were assessed.

RESULTS

Muscular men had a higher GFR (mean 186.4 mL/min; 95% CI 171.7-201.1) than normal BMI and obese groups (P = 0.0007). Urine protein and albumin excretion were not elevated in any participants. On multiple regression analysis (r(2) = 0.60), the variables with strong associations with GFR were age (P = 0.0009) and lean mass (P = 0.0001). Fat mass, protein intake and smoking status were not associated. Skeletal muscle mass correlated significantly with GFR in all subgroups.

CONCLUSION

Age and lean mass were strong determinants of GFR. Estimates of GFR should therefore be indexed to an estimate of lean mass.

Abdominal Adipose Tissue was Associated with Glomerular Hyperfiltration among Non- Diabetic and Normotensive Adults with a Normal Body Mass Index

Glomerular hyperfiltration is recognized as an early marker of progressive kidney dysfunction in the obese population. This study aimed to identify the relationship between glomerular hyperfiltration and body fat distribution measured by computed tomography (CT) in healthy Korean adults. The study population included individuals aged 20-64 years who went a routine health check-up including an abdominal CT scan. We selected 4,378 individuals without diabetes and hypertension. Glomerular filtration rate was estimated using the CKD-EPI equation, and glomerular hyperfiltration was defined as the highest quintile of glomerular filtration rate. Abdominal adipose tissue areas were measured at the level of the umbilicus using a 16-detector CT scanner, and the cross-sectional area was calculated using Rapidia 2.8 CT software. The prevalence of glomerular hyperfiltration increased significantly according to the subcutaneous adipose tissue area in men (OR = 1.74 (1.16-2.61), P for trend 0.016, for the comparisons of lowest vs. highest quartile) and visceral adipose tissue area in women (OR = 2.34 (1.46-3.75), P for trend < 0.001) in multivariate analysis. After stratification by body mass index (normal < 23 kg/m2, overweight ≥ 23 kg/m2), male subjects with greater subcutaneous adipose tissue, even those in the normal BMI group, had a higher prevalence of glomerular hyperfiltration (OR = 2.11 (1.17-3.80), P for trend = 0.009). Among women, the significance of visceral adipose tissue area on glomerular hyperfiltration resulted from the normal BMI group (OR = 2.14 (1.31-3.49), P for trend = 0.002). After menopause, the odds ratio of the association of glomerular hyperfiltration with subcutaneous abdominal adipose tissue increased (OR = 2.96 (1.21-7.25), P for trend = 0.013). Subcutaneous adipose tissue areas and visceral adipose tissue areas are positively associated with glomerular hyperfiltration in healthy Korean adult men and women, respectively. In post-menopausal women, visceral adipose tissue area shows significant positive association with glomerular hyperfiltration as in men.

Effect of Acetazolamide on Obesity-Induced Glomerular Hyperfiltration: A Randomized Controlled Trial

AIMS

Obesity is an important risk factor for the development of chronic kidney disease. One of the major factors involved in the pathogenesis of obesity-associated kidney disease is glomerular hyperfiltration. Increasing salt-delivery to the macula densa is expected to decrease glomerular filtration rate (GFR) by activating tubuloglomerular feedback. Acetazolamide, a carbonic anhydrase inhibitor which inhibits salt reabsorption in the proximal tubule, increases distal salt delivery. Its effects on obesity-related glomerular hyperfiltration have not previously been studied. The aim of this investigation was to evaluate whether administration of acetazolamide to obese non diabetic subjects reduces glomerular hyperfiltration.

MATERIALS AND METHODS

The study was performed using a randomized double-blind crossover design. Obese non-diabetic men with glomerular hyperfiltration were randomized to receive intravenously either acetazolamide or furosemide at equipotent doses. Twelve subjects received the allocated medications. Two weeks later, the same subjects received the drug which they had not received during the first study. Inulin clearance, p-aminohippuric acid clearance and fractional lithium excretion were measured before and after medications administration. The primary end point was a decrease in GFR, measured as inulin clearance.

RESULTS

GFR decreased by 21% following acetazolamide and did not decrease following furosemide. Renal vascular resistance increased by 12% following acetazolamide, while it remained unchanged following furosemide administration. Natriuresis increased similarly following acetazolamide and furosemide administration. Sodium balance was similar in both groups.

CONCLUSIONS

Intravenous acetazolamide decreased GFR in obese non-diabetic men with glomerular hyperfiltration. Furosemide, administered at equipotent dose, did not affect GFR, suggesting that acetazolamide reduced glomerular hyperfiltration by activating tubuloglomerular feedback.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01146288.

Association of age and BMI with kidney function and mortality: a cohort study

BACKGROUND

Compared with normal weight, obesity might be associated with worse clinical outcomes, including chronic kidney disease. Whether this association is modified by age is not known. We investigated the association of BMI with progressive loss of kidney function and all-cause mortality in US veterans.

METHODS

In a national cohort of 3,376,187 US veterans with an estimated glomerular filtration rate (eGFR) of more than 60 mL/min per 1·73 m(2), we assessed the association of BMI in patients of different ages (<40 years, 40 years to <50 years, 50 years to <60 years, 60 years to <70 years, 70 years to <80 years, and ≥80 years) with loss of kidney function and with all-cause mortality in logistic regression models and Cox proportional hazards models adjusted for ethnic origin, sex, comorbidities, medications, and baseline eGFR.

FINDINGS

274,764 (8·1%) of 3,376,187 veterans had a rapid decline in kidney function (decrease in slope of >5 mL/min per 1·73 m(2)). The lowest risk for loss of kidney function was noted in patients with BMI of at least 25 kg/m(2) but less than 30 kg/m(2). A generally consistent U-shaped association was noted between BMI and rapid loss of kidney function that was more prominent with increasing age, except in the patients younger than 40 years, in whom BMI did not seem to be predictive of renal function impairment. 672,341 veterans died (28·7 per 1000 patient-years, 95% CI 28·6-28·7) over a median follow-up of 6·8 years (IQR 6·5-7·7). BMI also showed a U-shaped association with mortality, which was similar in all age groups.

INTERPRETATION

A BMI of 30 kg/m(2) or more is associated with rapid loss of kidney function in patients with eGFR of at least 60 mL/min per 1·73 m(2), and this association is accentuated in older patients. A BMI of 35 kg/m(2) or more is also associated with high mortality. A BMI of at least 25 kg/m(2) but less than 30 kg/m(2) is associated with the best clinical outcomes.

FUNDING

National Institute of Health, Memphis VA Medical Center, Long Beach VA Healthcare System, Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Health Services Research and Development, and VA Information Resource Center.

Visceral adiposity index, hypertriglyceridemic waist phenotype and chronic kidney disease in a southern Chinese population: a cross-sectional study

OBJECTIVE

To explore the relationships between visceral adiposity index (VAI), hypertriglyceridemic waist phenotype (HW phenotype) and chronic kidney disease (CKD).

METHODS

A cross-sectional study was conducted in Zhuhai City June-October 2012. A total of 2142 participants were recruited. Logistic regression was used to evaluate the associations between VAI, HW phenotype and CKD.

RESULTS

After adjustment for age, VAI was significantly associated with CKD (OR 2.16, 95 % CI 1.25-3.74, P = 0.006) in women. Further adjusted for potential confounders, the association was still significant in women (OR 2.07, 95 % CI 1.17-3.64, P = 0.01). However, the association was abolished when adding diabetes and hypertension to the model (OR 1.68, 95 % CI 0.92-3.06, P = 0.09). The age-adjusted OR (95 % CI, P) of CKD associated with HW phenotype was 2.21 (1.29-3.76, 0.004) and 2.54 (1.53-4.22, <0.001) for men and women, respectively. Further adjusted for potential confounders, the associations were still significant in both subgroups. The OR for CKD was 2.41 (95 % CI 1.42-4.12, P = 0.001) and 2.32 (95 % CI 1.31-4.11, P = 0.004) for women and men, respectively. When further adjusted for diabetes and hypertension, the association of HW phenotype and CKD was significant (OR 1.88, 95 % CI 1.05-3.36, P = 0.033) in women. However, the model is abolished in men (OR 1.50, 95 % CI 0.81-2.78, P = 0.19).

CONCLUSION

Our results suggest that both VAI and the HW phenotype might be useful clinical indicators of CKD in China for females but not for males. The HW phenotype associated more strongly with CKD, compared with VAI.

The effects of weight change on glomerular filtration rate

BACKGROUND

Little is known about the effect of weight loss/gain on kidney function. Analyses are complicated by uncertainty about optimal body surface indexing strategies for measured glomerular filtration rate (mGFR).

METHODS

Using data from the African-American Study of Kidney Disease and Hypertension (AASK), we determined the association of change in weight with three different estimates of change in kidney function: (i) unindexed mGFR estimated by renal clearance of iodine-125-iothalamate, (ii) mGFR indexed to concurrently measured BSA and (iii) GFR estimated from serum creatinine (eGFR). All models were adjusted for baseline weight, time, randomization group and time-varying diuretic use. We also examined whether these relationships were consistent across a number of subgroups, including tertiles of baseline 24-h urine sodium excretion.

RESULTS

In 1094 participants followed over an average of 3.6 years, a 5-kg weight gain was associated with a 1.10 mL/min/1.73 m(2) (95% CI: 0.87 to 1.33; P < 0.001) increase in unindexed mGFR. There was no association between weight change and mGFR indexed for concurrent BSA (per 5 kg weight gain, 0.21; 95% CI: -0.02 to 0.44; P = 0.1) or between weight change and eGFR (-0.09; 95% CI: -0.32 to 0.14; P = 0.4). The effect of weight change on unindexed mGFR was less pronounced in individuals with higher baseline sodium excretion (P = 0.08 for interaction).

CONCLUSION

The association between weight change and kidney function varies depending on the method of assessment. Future clinical trials should examine the effect of intentional weight change on measured GFR or filtration markers robust to changes in muscle mass.

Higher filtration fraction in formerly early-onset preeclamptic women without comorbidity

Formerly preeclamptic women have an increased risk for developing end-stage renal disease, which has been attributed to altered renal hemodynamics and abnormalities in the renin-angiotensin-aldosterone system. Whether this is due to preeclampsia itself or to comorbid conditions is unknown. Renal hemodynamics and responsiveness to ANG II during low Na(+) intake (7 days, 50 mmol Na(+)/24 h) and high Na(+) (HS) intake (7 days, 200 mmol Na(+)/24 h) were studied in 18 healthy normotensive formerly early-onset preeclamptic women (fPE women) and 18 healthy control subjects (fHP women), all selected for absence of comorbidity. At the end of each diet, renal hemodynamics and blood pressure were measured before and during graded ANG II infusion. Both HS intake and former preeclampsia increased filtration fraction (FF) without an interaction between the two. FF was highest during HS intake in fPE women [0.31 ± 0.12 vs. 0.29 ± 0.11 in fHP women, generalized estimating equation analysis (body mass index corrected), P = 0.03]. The renal response to ANG II infusion was not different between groups. In conclusion, fPE women have a higher FF compared with fHP women. As this was observed in the absence of comorbidity, preeclampsia itself might exert long-term effects on renal hemodynamics. However, we cannot exclude the presence of prepregnancy alterations in renal function, which, in itself, lead to an increased risk for preeclampsia. In experimental studies, an elevated FF has been shown to play a pathogenic role in the development of hypertension and renal damage. Future studies, however, should evaluate whether the subtle differences in renal hemodynamics after preeclampsia contribute to the increased long-term renal risk after preeclampsia.