Association of Abdominal Adiposity with Cardiovascular Mortality in Incident Hemodialysis

Fat tissue quantity, waist circumference or waist-to-hip ratio in patients with chronic kidney disease: A systematic review and meta-analysis

The BMI predicts mortality and cardiovascular disease (CVD) in the general population, while in patients with end-stage chronic kidney disease (CKD) a high BMI is associated with improved survival, a phenomenon referred to as the "obesity paradox". While BMI is easy to determine and helps to categorize patients, it does not differentiate between fat tissue, lean tissue and bone mass. As the BMI may be altered in CKD, e.g. by muscle wasting, we determined in this meta-analysis (i) the association of mortality with fat tissue quantity in CKD and (ii) the association of mortality with abdominal obesity (as measured by waist circumference (WC) or waist-to-hip ratio (WHR)) in CKD. We systematically reviewed databases for prospective or retrospective cohort studies. In eleven studies with 23,523 patients the association between mortality and high fat tissue quantity in CKD was calculated. The pooled hazard ratio (HR) for this association in the CKD group in the dialysis group 0.91 (CI 0.84- 0.98, p = 0.01) which is comparable to the HR for the association with BMI. The HR in patients without dialysis was 0.7 (95% CI 0.53- 0.93, p = 0.01), suggesting a better risk prediction of high fat tissue content with mortality as compared to higher BMI with mortality in patients with CKD without dialysis. Importantly, both BMI and fat tissue quantity in CKD are described by the "obesity paradox": the higher the fat tissue content or BMI, the lower the mortality risk. In thirteen studies with 55,175 patients the association between mortality and high WC or WHR in CKD (with or without dialysis) was calculated. We observed, that the HR in the WHR group was 1.31 (CI 1.08-1.58, p = 0.007), whereas the overall hazard ratio of both groups was 1.09 (CI 1.01-1.18, p = 0.03), indicating that a higher abdominal obesity as measured by WHR is associated with higher mortality in CKD. Our analysis suggests gender-specific differences, which need larger study numbers for validation. This meta-analysis confirms the obesity paradox in CKD using fat tissue quantity as measure and further shows that using abdominal obesity measurements in the routine in obese CKD patients might allow better risk assessment than using BMI or fat tissue quantity. Comparable to the overall population, here, the higher the WHR, the higher the mortality risk.

Anthropometric Measures of Adiposity as Markers of Kidney Dysfunction: A Cross-Sectional Study

The present study was designed to provide information on the ability of several different anthropometric markers to reflect the renal impairment associated with body weight increase and to predict the development of renal alterations linked to overweight and obesity. In 574 subjects representative of the general population of the Pressioni Arteriose Monitorate e Loro Associazioni (PAMELA) study, with an age range between 57 and 73 years, we investigated the association between different anthropometric markers of body fat, as alternative to body mass index, and renal failure, to obtain information useful for determining their potential predictive value. Renal dysfunction was significantly associated with almost all anthropometric markers of adiposity related to body weight and body shape. After adjustment for confounders, such as age, sex, office blood pressure, serum glucose, antihypertensive drugs and smoking habit, association remained significant only for waist-to-hip ratio (WHR), lipid accumulation product (LAP) and visceral adiposity index (VAI). These 3 markers also displayed at the receiver operating curves (ROC) analysis the best ability to detect subjects with or without kidney dysfunction. The results of the present study provide evidence that WHR, LAP and VAI represent the best markers of renal dysfunction associated with visceral body fat accumulation.

Sarcopenic obesity and its relation with muscle quality and mortality in patients on chronic hemodialysis

BACKGROUND & AIMS

Sarcopenia is prevalent in patients with end-stage kidney disease (ESKD) on hemodialysis (HD), and is associated with poor outcomes, while obesity may be protective. Sarcopenic obesity is associated with increased frailty, morbidity and mortality in the general population. Myosteatosis, i.e., muscle fat infiltration, has major effects on muscle strength and physical performance, but is poorly investigated in the nephrology setting. In the present study we aimed to assess the association between sarcopenic obesity, as diagnosed by abdominal CT, and mortality. Moreover, the relationship between myosteatosis, sarcopenic obesity and mortality was also investigated.

METHODS

This is a retrospective study in which ESKD patients on HD submitted to unenhanced abdominal CT for clinical reasons at least 6 months after dialysis initiation were evaluated for sarcopenic obesity and myosteatosis, defined as intermuscular fat area and low attenuation muscle area. Sarcopenic obesity was diagnosed in cases of low abdominal skeletal muscle area and high total fat area. Receiver-operating characteristics (ROC) analysis with Youden index was used to determine the cut-off for high total fat area. Intermuscular fat area and low attenuation muscle area were evaluated by applying the Hounsfield unit of interest (-190; -30, and -29; +29 respectively). Cox regression analysis was used to evaluate the association between predictors and mortality risk.

RESULTS

We enrolled 212 patients, aged 68.8 (±14.7) years, 65.5% (139/212) male. Median follow-up was 19.7 (interquartile range [IQR] 2.7-35) months. Sarcopenic obesity was diagnosed in 19.8% of patients and was associated with increased mortality (HR: 3.29 (1.72; 6.27), P < 0.001), and with the presence of myosteatosis. Both intermuscular fat area and low attenuation muscle area were associated with increased mortality in adjusted analyses.

CONCLUSIONS

Patients with sarcopenic obesity have increased myosteatosis. Sarcopenic obesity and myosteatosis are associated with increased mortality in patients on HD.

Central obesity as assessed by conicity index and a-body shape index associates with cardiovascular risk factors and mortality in kidney failure patients

Background

Anthropometric indices of central obesity, waist circumference (WC), conicity index (CI), and a-body shape index (ABSI), are prognostic indicators of cardiovascular (CV) risk. The association of CI and ABSI with other CV risk indices, markers of nutritional status and inflammation, and clinical outcomes in chronic kidney disease (CKD) stage 5 (CKD5) patients was investigated.

Methods

In a cross-sectional study with longitudinal follow up of 203 clinically stable patients with CKD5 (median age 56 years; 68% males, 17% diabetics, 22% with CV disease, and 39% malnourished), we investigated CI and ABSI and their associations with atherogenic index of plasma (AIP), Framingham CV risk score (FRS), Agatston scoring of coronary artery calcium (CAC) and aortic valve calcium (AVC), handgrip strength (HGS), high sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6). CV events (CVE) and all-cause mortality during up to 10-years follow up were analyzed by multivariate survival analysis of restricted mean survival time (RMST).

Results

Chronic kidney disease patients with middle and highest CI and ABSI tertiles (indicating greater abdominal fat deposition), compared to those with the lowest CI and ABSI tertiles, tended to be older, more often men and diabetic, had significantly higher levels of hsCRP, IL-6, AIP, FRS, CAC and AVC scores. CI and ABSI were positively correlated with CAC, FRS, AIP, hsCRP and IL-6. Both CI and ABSI were negatively correlated with HGS. In age-weighted survival analysis, higher CI and ABSI were associated with higher risk of CVE (Wald test = 4.92, p = 0.027; Wald test = 4.95, p = 0.026, respectively) and all-cause mortality (Wald test = 5.24, p = 0.022; Wald test = 5.19, p = 0.023, respectively). In RMST analysis, low vs. high and middle tertiles of CI and ABSI associated with prolonged CVE-free time and death-free time, and these differences between groups increased over time.

Conclusion

Abdominal fat deposit indices, CI and ABSI, predicted CV outcomes and all-cause mortality, and were significantly associated with the inflammatory status in CKD patients.

Low BMI and high waist-to-hip ratio are associated with mortality risk among hemodialysis patients: a multicenter prospective cohort study

Background

Data are limited on the relationship between waist-to-hip ratio (WHR) and mortality risk among maintenance hemodialysis (MHD) patients. Moreover, the combined association of body mass index (BMI) and WHR with mortality remains uncertain. Therefore, we aimed to explore the individual and combined association of BMI and WHR with the all-cause and cardiovascular disease (CVD) mortality.

Methods

In this multicenter prospective cohort study, we enrolled 1034 MHD patients. The primary outcome was all-cause mortality and secondary outcome was CVD mortality. Multivariable Cox proportional hazards models were used to evaluate the individual and combined association of BMI and WHR with the risk of mortality.

Results

A nonlinear inverse relationship was found between BMI and risk of all-cause mortality (P for nonlinearity <.05). Being underweight (<18.5 kg/m²) was associated with higher all-cause mortality risk (HR 1.45; 95% CI 1.08-1.94) compared with normal weight (18.5-23.9 kg/m²), while being overweight (24-27.9 kg/m²; HR 0.96; 95% CI 0.70-1.31) and obese (≥28 kg/m²; HR 1.19; 95% CI 0.62-2.26) showed no significant differences. Of note, WHR was independently and positively associated with all-cause mortality (per standard deviation increase, HR 1.13; 95% CI 1.00-1.27). When analyzed jointly, patients with low BMI (<18.5 kg/m²) and high WHR (≥0.95) had the highest risk of all-cause mortality. Similar results were obtained for CVD mortality.

Conclusions

In patients undergoing hemodialysis from China, low BMI and high WHR were individually and jointly associated with higher risk of mortality. Our results emphasize that BMI and WHR may jointly affect the prognosis of MHD patients.

U-Shaped Association between Waist-to-Hip Ratio and All-Cause Mortality in Stage 3-5 Chronic Kidney Disease Patients with Body Mass Index Paradox

The obesity paradox, referring to the association of high body mass index (BMI) with low all-cause mortality risk, is found in patients with chronic kidney disease (CKD). Central obesity is associated with metabolic syndrome and may have better prognostic value than BMI for all-cause mortality. Whether central obesity is associated with all-cause mortality in cases of obesity paradox in CKD patients remains unknown. We included 3262 patients with stage 3–5 CKD, grouped into five quintiles (Q1–5) by waist-to-hip ratio (WHR). Low WHR and BMI were associated with malnutrition and inflammation. In Cox regression, high BMI was not associated with all-cause mortality, but BMI < 22.5 kg/m² increased the mortality risk. A U-shaped association between central obesity and all-cause mortality was found: WHR Q1, Q4, and Q5 had higher risk for all-cause mortality. The hazard ratio (95% confidence interval) of WHR Q5 and Q1 for all-cause mortality was 1.39 (1.03–1.87) and 1.53 (1.13–2.05) in male and 1.42 (1.02–1.99) and 1.28 (0.88–1.85) in female, respectively. Waist-to-height ratio and conicity index showed similar results. Low WHR or low BMI and high WHR, but not high BMI, are associated with all-cause mortality in advanced CKD.

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

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