Serum Creatinine Modifies Associations between Body Mass Index and Mortality and Morbidity in Prevalent Hemodialysis Patients

Observational study on obesity: Insights from middle-aged and elderly college staff in Beijing

Obesity poses a serious global public health challenge, particularly among middle-aged, and elderly college staff. This study aims to explore the associated factors of obesity by analyzing the metabolic indicators of 1756 university staff from Minzu University of China, Beijing. Venous blood samples were collected, and blood metabolic indicators were analyzed. The results indicate that middle-aged faculty members are more susceptible to obesity compared to their younger counterparts. Multiple linear regression analysis revealed that BMI values increase with age (B = 0.074, P < .001), uric acid (B = 0.008, P < .001), alanine transaminase (B = 0.043, P < .001), low-density lipoprotein (B = 1.941, P < .001), triglycerides (B = 0.544, P < .001), total cholesterol (TC, B = -1.582, P < .001), and other factors, while decreasing with the increase of high-density lipoprotein (B = -1.493, P < .001). In light of these findings, it is recommended that middle-aged and elderly college staff undergo regular blood indicator checks and enhance weight management to mitigate the risk of obesity and promote their overall health.

Equations to Estimate the Normalized Creatinine Generation Rate (CGRn) in 3/Week Dialysis Patients With or Without Residual Kidney Function

OBJECTIVE

Normalized creatinine generation rate (CGRn) can be computed for a variety of dialysis schedules using a recently described kinetic modeling program. However, the availability of estimating equations might facilitate broader study of this metric. We developed equations to estimate CGRn based on modeling and then tested them against modeled CGRn values in the Frequent Hemodialysis Network Nocturnal Trial baseline (3/week) dataset.

DESIGN AND METHODS

We used a "what-if" derivation of a previously published variable volume 2-pool creatinine kinetic model to generate predicted predialysis values of serum creatinine that would result from creatinine generation rates of 250-2000 mg/day in patients with creatinine distribution volumes of 20 to 50 L, dialyzed from 60 to 480 min per treatment three times a week. Then, in patients with residual kidney function, we calculated an "anuric expected predialysis serum creatinine value" before applying the same equations. We then compared estimated CGRn values as predicted by this approach with modeled values in patient data from the Frequent Hemodialysis Network Nocturnal Trial.

RESULTS

The estimating equations for CGRn yielded results similar to those obtained with formal modeling, in both anuric patients and those with residual kidney function, with mean percent error of 0.845 ± 6.15 (SD) in anuric patients, and ‒0.29 ± 4.90 in patients with a mean creatinine clearance of 5.44 ± 4.82 mL/min, with R-squared values of 0.96 in both anuric patients and those with residual renal clearance of creatinine.

CONCLUSIONS

In patients dialyzed 3/week, CGRn can be estimated using prediction equations. Use of these equations may facilitate broader investigation of CGRn as a measure of nutritional status and outcome.

Sex-specific analysis of haemodialysis prevalence, practices and mortality over time: the Austrian Dialysis Registry from 1965 to 2014

BACKGROUND

Despite a higher prevalence of chronic kidney disease among women, more men than women start renal replacement therapy (RRT). We hypothesized that gender differences in health care access exist and therefore aimed at determining whether characteristics and outcomes of haemodialysis patients over time differ by sex.

METHODS

We studied all 28 323 adults who began haemodialysis during 1965-2014 in the Austrian Dialysis Registry, analysing trends in patient characteristics by sex and decade with mortality (via Cox regression), which was compared with the mortality of the Austrian general population.

RESULTS

More men than women started haemodialysis (60.1% men versus 39.9% women overall), with minor differences among decades and age groups. The male:female mortality rate ratio in the general population ranged from 1.2 to 2.4 for age groups >18 years and in haemodialysis patients ranged from 0.80 to 1.3 (closer to 1 than in the general population, but consistently >1 in Decades 3-5). In recent decades, diabetes and hypertension replaced glomerulonephritis as the primary cause of end-stage renal disease in both men and women. Interaction analyses showed the mortality risk associated with haemodialysis access (only recorded in Decade 5) was significantly lower for men than for women.

CONCLUSIONS

The male:female mortality rate ratio and the proportion of women starting haemodialysis were remarkably stable, which does not support the hypothesis of gender differences in health care/haemodialysis access or could imply that such differences might have persisted over decades. Future research should expand to other countries and other forms of RRT.

Alpha lipoic acid supplementation improved antioxidant enzyme activities in hemodialysis patients

Background: Cardiovascular disease (CVD) is the main cause of death in hemodialysis (HD) patients and oxidative stress is an important risk factor for CVD. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) are primary antioxidant enzymes in human cells acting against toxic reactive oxygen species (ROS) and their reduced activity may contribute to oxidative disorders in HD patients. Alpha lipoic acid (ALA) as a potent strong antioxidant may affect these enzymes. Objective: We examined the effects of ALA supplementation on antioxidant enzyme activities in HD patients. Method: In this double-blinded, randomized clinical trial, 63 HD patients (43 males and 20 females; age range: 22-79 years) were assigned into the ALA group (n: 31), receiving a daily dose of ALA (600 mg), or a control group (n: 32), receiving placebo for 8 weeks. Body mass index (BMI), antioxidant enzymes, albumin (Alb) and hemoglobin (Hb) were determined before and after intervention. Results: At baseline, the mean blood activities of SOD, GPx, and CAT in ALA group were 1032±366, 18.9±5.09 and 191±82.7 U/gHb which increased at the end of study to 1149±502, 19.1±7.19 and 208±86.6 U/gHb respectively. However, only the increase of SOD was statistically significant in comparison with placebo group (P = 0.04). The mean levels of Alb, Hb, weight and BMI were not significantly changed in study groups (P>0.05). Conclusion: ALA may be beneficial for HD patients by increasing the activity of antioxidant enzymes; however, further studies are needed to achieve precise results.

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

Background

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

Methods

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

Results

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

Conclusion

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

Complex inter-relationship of body mass index, gender and serum creatinine on survival: exploring the obesity paradox in melanoma patients treated with checkpoint inhibition

BACKGROUND

A male gender driven obesity paradox (improved survival for overweight/obese patients compared to normal weight) was recently shown in melanoma in the context of checkpoint inhibition (anti-PD-1/anti-CTLA4 monotherapy) in a pooled meta-analysis. We characterized the relationship of Body Mass Index (BMI) with survival and explored gender-based interactions with surrogates of body composition/malnutrition in the context of PD-1 blockade as monotherapy or in combination with ipilimumab in a real-world setting.

METHODS

Advanced melanoma patients who received at least one dose of pembrolizumab, nivolumab, or nivolumab plus ipilimumab (combination) from June 2014 to September 2016 were included in this retrospective cohort study (N = 139). Overall Survival (OS) and Progression Free Survival (PFS) were the main outcomes. Analysis was performed using Random Survival Forests (RSF)/ multivariable Cox Proportional-Hazards models.

RESULTS

Overweight/Class-I (25- < 35 kg/m²) obese patients had a significantly lower risk of mortality (adjusted-HR:0.26; 95%CI:0.1-0.71; p-value = 0.008) and progressive disease (adjusted-HR:0.43; 95%CI:0.19-0.95; p-value:0.038) compared to normal-weight (18.5- < 25 kg/m²). Class II/III obesity (compared to normal-weight) had an adjusted HR of 0.42 (95%CI: 0.1-1.77; p-value: 0.238) for OS and 1 (95%CI:0.34-2.94; p-value:0.991) for PFS. Exploration of interactions for OS showed that the association was predominantly driven by males (adjusted-HR_males:0.11; 95%CI:0.03-0.4; adjusted-HR_females: 0.56; 95%CI:0.16-1.89_; p-value_interaction:0.044); the association was not seen in patients with serum creatinine< 0.9 mg/dL (adjusted-HR:0.43; 95%CI:0.15-1.24; p-value_interaction:0.020), who were predominantly females. These observations were made in both the anti-PD-1 monotherapy (n = 79) and combination therapy (anti-PD-1/CTLA-4, n = 60) cohorts.

CONCLUSIONS

The findings support the existence of an "obesity paradox" restricted to overweight/Class-I obesity in the real-world setting; the association was driven predominantly by males who largely had higher serum creatinine levels, a surrogate for skeletal muscle mass in the setting of metastatic disease. These observations suggest that sarcopenia (low skeletal muscle mass) or direct measures of body mass composition may be more suitable predictors of survival in melanoma patients treated with PD-1 blockade (monotherapy/combination).

Low serum creatinine predicts risk for type 2 diabetes

AIMS

As an insulin target tissue, skeletal muscle is inversely related to type 2 diabetes mellitus (T2DM). Serum creatinine originates mainly from creatine in muscle and is considered as a reliable surrogate marker for muscle mass in apparently healthy subjects. It is therefore hypothesized that low serum creatinine could effectively predict increased risk of T2DM. Yet information is scarce regarding the longitudinal relationship between serum creatinine and T2DM. This study aims to investigate this relation in a large general population of both men and women.

METHODS

A prospective cohort study (n = 57 587; follow-up range: 1-9 years, mean: 3.57 years, 95% confidence interval: 3.55-3.58 years) was conducted in a general population sample from Tianjin, China. Multivariable Cox proportional hazards regression models were used to assess the relationship between baseline serum creatinine and the risk of developing T2DM (as defined by the American Diabetes Association criteria).

RESULTS

During the follow-up period, 2017 subjects developed T2DM. The multivariate-adjusted hazard ratios (95% confidence interval) for T2DM incidence across quintiles of serum creatinine were 1.00 (reference), 0.86 (0.75, 0.99), 0.82 (0.72, 0.94), 0.85 (0.74, 0.97), and 0.77 (0.67, 0.89; P for trend <.01). Similar results were observed in both sexes (interaction P = .56).

CONCLUSIONS

These findings indicate that serum creatinine concentration is inversely related to incident T2DM in both men and women. Measuring serum creatinine may assist in the early detection of individuals at high risk of developing T2DM.

Visceral, general, abdominal adiposity and atherogenic index of plasma in relatively lean hemodialysis patients

Background

Obesity is a well-established risk factor for atherosclerosis. However, it is unknown which measure of adiposity best relates to atherosclerosis in relatively lean maintenance hemodialysis (MHD) patients. We aimed to explore and compare the associations between different adiposity indices reflecting general, abdominal, visceral adiposity and arteriosclerosis risk with atherogenic index of plasma(AIP) in relatively lean MHD patients.

Methods

We conducted a multicenter, cross-sectional study in Guizhou Province, Southwest China. General/abdominal adiposity indices like body mass index (BMI), waist circumference(WC), waist-height ratio(WHtR), conicity index (Ci) and visceral obesity indices including visceral adiposity index (VAI), lipid accumulation product (LAP) and the hypertriglyceridemic waist phenotype (HW phenotype) were recorded. Univariate and multivariate linear regression models were used.

Results

All adiposity indices correlated positively with AIP in univariate analysis both in men and women except for Ci. After adjustment for age and traditional atherosclerosis risk factors, BMI, WC, WHtR, VAI and LAP still had associations with AIP both in men (β = 0.265, 0.153, 0.16, 0.788 and 0.74, respectively, all P < 0.001) and women (β = 0.34,0.199, 0.21, 0.83 and 0.74, respectively, all P < 0.001). After further adjustment for BMI, associations between AIP and VAI, LAP remained significant, but associations between WC, WHtR and AIP disappeared.

Conclusions

The HW phenotype, VAI, and LAP, validated and convenient markers of visceral obesity, were superior to classical anthropometric general/ abdominal adiposity indices for atherosclerosis risk assessment, especially in relatively lean MHD patients aged 40 years or older.

The Incidence and Pathophysiology of the Obesity Paradox: Should Peritoneal Dialysis and Kidney Transplant Be Offered to Patients with Obesity and End-Stage Renal Disease?

PURPOSE OF REVIEW

To educate nephrologists and primary-care physicians about the incidence, pathophysiology, and survival benefits of the obesity paradox in end-stage renal disease (ESRD). This review also discusses the future of kidney transplant and peritoneal dialysis in obese dialysis patients.

RECENT FINDINGS

Obesity paradox in ESRD was first reported three decades ago, and since then, there have been several epidemiological studies that confirmed the phenomenon. Regardless of the anthropometric indices used to define obesity in ESRD patients, these markers serve to predict the dialysis patient's survival. The pathophysiology of obesity paradox tends to be multifactorial. Recent cohort studies demonstrated a survival benefit in all race and ethnic groups, but Hispanics and blacks experienced increased survival rates when compared to non-Hispanic whites. Obese dialysis patients should be offered peritoneal dialysis, especially if they are new to dialysis and have an adequate renal residual function. Several studies have shown that the benefit of receiving kidney transplant in obese patients exceeds the risks. The robotic-assisted kidney transplant (RAKT) procedure is the latest innovation that could offer hope for obese dialysis patients who have been denied or are waiting for kidney transplant. The obesity paradox phenomenon in ESRD is a unique illustration of survival benefit in a population that has a high overall annual mortality. Peritoneal dialysis should be encouraged for obese patients who have preserved residual renal function. Kidney transplant centers should encourage RAKT utilization in obese dialysis patients instead of denying them a kidney transplant.

Relation of Lean Body Mass and Muscle Performance to Serum Creatinine Concentration in Hemodialysis Patients

INTRODUCTION

Serum creatinine concentration is an important uremic marker and predictor of survival in dialysis patients. This cross-sectional case-control study was made to quantitatively describe the relation between lean body mass (LBM), physical performance measures, and serum creatinine values.

METHODS

Ninety hemodialysis patients and 106 controls were measured by bioimpedance spectroscopy, handgrip strength, sit-to-stand test, and biochemical serum tests. Univariate and multivariate general linear models were used to analyze quantitative relations.

RESULTS

At univariate regression LBM accounted for 13.6% variability of serum creatinine concentration. In adjusted analyses with age, height, and body mass, LBM persisted as the only significant predictor of midweek predialysis serum creatinine concentration. Physical performance measures handgrip strength and sit-to-stand performance did not improve prediction of serum creatinine. With addition of serum urea concentration and residual diuresis the predictive value of the regression model improved to account for 45% of serum creatinine variability. Each kg of LBM was associated with 7.7 μmol/l increase in creatinine concentration (95% CI 3.4-12.1, p=0.001).

CONCLUSION

Bioimpedance derived LBM has a significant linear relation with predialysis serum creatinine concentrations. Hereby described quantitative relation should help clinicians to better evaluate observed creatinine concentrations of hemodialysis patients when bioimpedance derived LBM is available.

Body Mass Index Change and Hospitalization Risk in Elderly Hemodialysis Patients: Results from Japanese Dialysis Outcomes and Practice Patterns Study

BACKGROUND

Short-term weight gains and losses are associated with a lower and higher mortality risk, respectively, in patients undergoing hemodialysis (HD). However, little is known about their association with the risk of subsequent hospitalization.

METHODS

In a prospective cohort of 1,804 HD patients aged ≥65 years enrolled in the Japanese Dialysis Outcomes and Practice Patterns Study phases 3 (2005-2008) and 4 (2009-2011), we examined the associations between changes in body mass index (BMI) over a 4-month baseline period (<-3%, -3 to <-1%, -1 to <1% [reference], 1 to <3%, and ≥3%) and subsequent risk of all-cause, cardiovascular, and noncardiovascular hospitalization using Cox models with adjustment for potential confounders.

RESULTS

During a median follow-up of 1.2 years, we noted 1,028 incident hospitalizations for any cause, including 275 and 753 hospitalizations for cardiovascular and noncardiovascular causes, respectively. An L-shaped association was observed between BMI change and all-cause hospitalization. The multivariable-adjusted hazard ratios (HRs; 95% CI) of all-cause hospitalization associated with BMI changes of <-3%, -3 to <-1%, 1 to <3%, and ≥3% (vs. -1 to <1%) were 1.29 (1.01-1.65), 1.22 (0.98-1.51), 1.04 (0.83-1.29), and 1.10 (0.83-1.45), respectively. Qualitatively similar associations were present for cardiovascular-related hospitalization (corresponding HRs [95% CI]: 1.58 [1.06-2.37], 1.09 [0.75-1.58], 0.99 [0.72-1.36], and 0.91 [0.51-1.64], respectively) but not for noncardiovascular-related hospitalization (corresponding HRs [95% CI]: 1.19 [0.90-1.57], 1.26 [0.99-1.59], 1.06 [0.84-1.35], and 1.18 [0.86-1.63], respectively).

CONCLUSIONS

Decreases in BMI over a relatively short-term period were independently associated with higher risk of subsequent hospitalization, particularly cardiovascular-related hospitalization, among elderly HD patients.

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

Background

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

Methods

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

Results

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

Conclusions

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

Body Size and Outcomes in Dialysis and Transplant Patients - Does it Matter?

The terminologies of "body size", "body mass index (BMI)", "body weight", "large BMI" and "obesity" are controversial for defining the effects of "adiposity" or "fat excess" on the outcomes of dialysis and transplant patients. However, probably these terminologies will be continued to be used in the future as well, because of being older and simpler terminologies. In the general population obesity is a powerful risk factor for cardiovascular morbidity and mortality, while, it conferred a survival advantage to dialysis patients. However, this may be a oversimplification, since obesity may still be a risk factor in non-sarcopenic hemodialysis patients. Obesity is associated with early post-transplant adverse effects (i.e. delayed graft function, graft failure, wound infections, also transplant costs) and unfavorable graft and patient survival. However, thanks to safer immunosuppressive protocols, recently graft and patient survival is similar in obese as those of the non-obese patients. On the other hand, morbid obesity may still be a cause of unfavorable patient and graft survival. Since obese transplant recipients have better life expectancy as compared to wait-listed hemodialysis patients, they should be transplanted as well, while morbidly obese patients should be asked to lose weight before being placed in the waiting lists.