A matched comparison of serum lipids between hemodialysis patients and nondialysis morbid controls

Effects of oral non-protein calorie supplements on nutritional status among maintenance hemodialysis patients with protein-energy wasting: a multi-center randomized controlled trial

Protein-energy wasting (PEW) is prevalent in maintenance hemodialysis (MHD) patients, and is one of the major risk factors for poor outcomes and death. This study aimed to investigate the effects of non-protein calorie supplements on the nutritional status of MHD patients with PEW. MHD patients with PEW were enrolled in this multi-center, open-label, randomized controlled trial. Then, they were randomly assigned to the intervention group to receive the non-protein calorie supplements containing 280 kcal of energy every day for 6 months or the control group to complete all aspects of the study without receiving supplements. Patients in both groups received dietary counselling from dietitians. Data on nutritional assessments, anthropometric measurements, blood analysis and dietary recall were collected at the baseline and at six months from both groups. Statistical analyses were performed using analysis of covariance (ANCOVA) adjusted for sex and baseline values. Ninety-two MHD patients completed the study. A significant increase in the subjective global assessment (SGA) score was found in the intervention group compared with the control group (4.88 ± 1.41 vs. 4.40 ± 1.16, p = 0.044). The ratio of PEW patients (diagnosed with SGA ≤5) in the intervention group (61.2%) was also significantly lower than that in the control group (83.7%) (p < 0.001). Moreover, significant improvements in body mass index (20.81 ± 2.46 kg m^-2vs. 19.51 ± 2.60 kg m^-2, p < 0.001), nutrition risk screening 2002 (2.45 ± 1.40 vs. 3.12 ± 1.37, p = 0.038), mid-upper arm circumference (23.30 ± 2.78 cm vs. 21.75 ± 2.87 cm, p = 0.001), and mid-arm muscle circumference (20.51 ± 2.32 cm vs. 19.06 ± 2.92 cm, p = 0.005) were observed in the intervention group compared with the control group. Patients in the intervention group took in more dietary energy than the control group (26.96 ± 4.75 kcal per kg body weight per day vs. 24.33 ± 2.68 kcal per kg body weight per day, p < 0.001). In conclusion, non-protein calorie supplements may improve the nutritional status of MHD patients with PEW.

Long-term weight loss as a predictor of mortality in haemodialysis patients

BACKGROUND

Serial weight decrease can be a prognostic predictor in chronic haemodialysis (HD) patients. We investigated the impact of long-term post-HD body weight (BW) changes on all-cause mortality among HD patients.

METHODS

This longitudinal cohort study and post-hoc analysis evaluated participants of a previous randomised controlled trial conducted between 2006 and 2011 who were followed up until 2018. Weight change slopes were generated with repeated measurements every 6 months during the trial for patients having ≥5 BW measurements. Participants were categorised into four groups based on quartiles of weight change slopes; the median weight changes per 6 months were -1.02 kg, -0.25 kg, +0.26 kg, and +0.86 kg. Cox proportional hazard regression was used to evaluate differences in subsequent survival among the four groups. BW trajectories were plotted with a backward time-scale and multilevel regression analysis to visualise the difference in BW trajectories between survivors and non-survivors.

RESULTS

Among the 461 patients, 404 were evaluated, and 168 (41.6%) died within a median follow-up period of 10.2 years. The Cox proportional hazard regression adjusted for covariates and baseline BW showed that a higher rate of weight loss was associated with higher mortality. The hazard ratios were 2.02 (1.28-3.20), 1.77 (1.10-2.85), 1.00 (reference), and 1.11 (0.67-1.83) for the first, second, third (reference), and fourth quartiles, respectively. BW trajectories revealed a significant decrease in BW in non-survivors.

CONCLUSIONS

Weight loss elucidated by serial BW measurements every 6 months is significantly associated with higher mortality among HD patients.

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

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

Dietary restrictions in dialysis patients: is there anything left to eat?

A significant number of dietary restrictions are imposed traditionally and uniformly on maintenance dialysis patients, whereas there is very little data to support their benefits. Recent studies indicate that dietary restrictions of phosphorus may lead to worse survival and poorer nutritional status. Restricting dietary potassium may deprive dialysis patients of heart-healthy diets and lead to intake of more atherogenic diets. There is little data about the survival benefits of dietary sodium restriction, and limiting fluid intake may inherently lead to lower protein and calorie consumption, when in fact dialysis patients often need higher protein intake to prevent and correct protein-energy wasting. Restricting dietary carbohydrates in diabetic dialysis patients may not be beneficial in those with burnt-out diabetes. Dietary fat including omega-3 fatty acids may be important caloric sources and should not be restricted. Data to justify other dietary restrictions related to calcium, vitamins, and trace elements are scarce and often contradictory. The restriction of eating during hemodialysis treatment is likely another incorrect practice that may worsen hemodialysis induced hypoglycemia and nutritional derangements. We suggest careful relaxation of most dietary restrictions and adoption of a more balanced and individualized approach, thereby easing some of these overzealous restrictions that have not been proven to offer major advantages to patients and their outcomes and which may in fact worsen patients' quality of life and satisfaction. This manuscript critically reviews the current paradigms and practices of recommended dietary regimens in dialysis patients including those related to dietary protein, carbohydrate, fat, phosphorus, potassium, sodium, and calcium, and discusses the feasibility and implications of adherence to ardent dietary restrictions and future research.

Obesity paradox in end-stage kidney disease patients

In the general population, obesity is associated with increased cardiovascular risk and decreased survival. In patients with end-stage renal disease (ESRD), however, an "obesity paradox" or "reverse epidemiology" (to include lipid and hypertension paradoxes) has been consistently reported, i.e. a higher body mass index (BMI) is paradoxically associated with better survival. This survival advantage of large body size is relatively consistent for hemodialysis patients across racial and regional differences, although published results are mixed for peritoneal dialysis patients. Recent data indicate that both higher skeletal muscle mass and increased total body fat are protective, although there are mixed data on visceral (intra-abdominal) fat. The obesity paradox in ESRD is unlikely to be due to residual confounding alone and has biologic plausibility. Possible causes of the obesity paradox include protein-energy wasting and inflammation, time discrepancy among competitive risk factors (undernutrition versus overnutrition), hemodynamic stability, alteration of circulatory cytokines, sequestration of uremic toxin in adipose tissue, and endotoxin-lipoprotein interaction. The obesity paradox may have significant clinical implications in the management of ESRD patients especially if obese dialysis patients are forced to lose weight upon transplant wait-listing. Well-designed studies exploring the causes and consequences of the reverse epidemiology of cardiovascular risk factors, including the obesity paradox, among ESRD patients could provide more information on mechanisms. These could include controlled trials of nutritional and pharmacologic interventions to examine whether gain in lean body mass or even body fat can improve survival and quality of life in these patients.

Lipids, waist circumference and body mass index in haemodialysis patients

In the general population, dyslipidaemia and abdominal obesity are risk factors for cardiovascular disease, but less is known about their roles in patients on maintenance haemodialysis (HD). This study investigated the association between blood lipids and abdominal obesity, as determined by waist circumference (WAC), and body mass index (BMI) in 72 HD patients (32 women). Blood lipid levels were measured using routine laboratory methods. Abdominal obesity, based on the WAC measurement, was found in 62.5% of HD patients (75.0% of women; 52.5% of men). Triglyceride levels were higher in abdominally obese compared with abdominally non-obese men. According to BMI measurements, 34.7% of HD patients were overweight/obese and 9.7% were underweight. In men, WAC and BMI were positively correlated with triglyceride levels. In women, WAC was negatively correlated with high-density lipoprotein (HDL) cholesterol and apolipoprotein A levels. The results indicated that there was a negative association of abdominal obesity and BMI with HDL cholesterol in HD patients.

Novel lipoprotein subfraction and size measurements in prediction of mortality in maintenance hemodialysis patients

BACKGROUND AND OBJECTIVES

Conventional lipid profiles usually cannot predict cardiovascular outcomes in chronic disease states. We hypothesized that novel lipoprotein subfraction concentrations and LDL particle size measurements better predict mortality in maintenance hemodialysis (MHD) patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Mortality-predictability of LDL particle diameter and lipoprotein subfraction concentrations, measured by novel ion mobility, was examined in a cohort of 235 hemodialysis patients who were followed for up to 6 years using Cox models with adjustment for important covariables.

RESULTS

Patients were 54 ± 14 years old (mean ± SD) and included 45% women with total, LDL and HDL cholesterol levels of 143 ± 42, 76 ± 29, and 37 ± 12 mg/dl, respectively. Over 6 years, 71 patients (31%) died. Conventional lipid profile was not associated with mortality. The death hazard ratio (HR, 95% confidence interval) of the highest versus lowest quartiles of very small and large LDL particle concentrations were 2.43 (1.03 to 5.72) and 0.38 (0.15 to 0.96), respectively. Across increasing quartiles of LDL particle diameter, death HRs were 1.00, 0.93 (0.46 to 1.87), 0.43 (0.21 to 0.89), and 0.45 (0.31 to 1.00), respectively.

CONCLUSIONS

Whereas conventional lipid profile cannot predict mortality in MHD patients, larger novel LDL particle diameter or higher large LDL particle concentrations appear predictive of greater survival, whereas higher very small LDL particle concentration is associated with higher death risk. Examining lipoprotein subfraction modulation in chronic diseases is indicated.

[Obesity in haemodialysis: the paradox]

Overweight, as well as obesity have become mass phenomena with an ever increasing prevalence in most countries all over the world, and are associated with a greater cardiovascular risk and mortality. Weight excess is usually directly related to an additional risk of morbidity and mortality in the general population. In contrast, in patients with end-stage renal disease (ESDR) under haemodialysis a paradox has been reported, showing that an increased body mass index (BMI) was associated with better survival, and vice versa. This paradox relationship, sometimes referred to as "reverse epidemiology" proved to be relatively constant in chronic haemodialysis and to a lesser extent in peritoneal dialysis. Reverse epidemiology is also found in haemodialysis patients for other risk factors, such hypertension, or hypercholesterolaemia. And, likewise, this phenomenon is also observed in other populations of heavy chronic disease suggesting a potential selection bias, such as a real survival benefit for obesity in case of the presence of another heavy chronic disease. The possible causes and mechanisms of reverse epidemiology are reviewed in this article.

Alpha-tocopherol supplementation decreases electronegative low-density lipoprotein concentration [LDL(-)] in haemodialysis patients

BACKGROUND

Oxidative stress is a significant contributor to cardiovascular diseases (CVD) in haemodialysis (HD) patients, predisposing to the generation of oxidized low-density lipoprotein (oxLDL) or electronegatively charged LDL subfraction. Antioxidant therapy such as alpha-tocopherol acts as a scavenger of lipid peroxyl radicals attenuating the oxidative stress, which decreases the formation of oxLDL. The present study was designed to investigate the influence of the alpha-tocopherol supplementation on the concentration of electronegative low-density lipoprotein [LDL(-)], a minimally oxidized LDL, which we have previously described to be high in HD patients.

METHODS

Blood samples were collected before and after 120 days of supplementation by alpha-tocopherol (400 UI/day) in 19 stable HD patients (50 +/- 7.8 years; 9 males). The concentrations of LDL(-) in blood plasma [using an anti-LDL- human monoclonal antibody (mAb)] and the anti-LDL(-) IgG auto-antibodies were determined by ELISA. Calculation of body mass index (BMI) and measurements of waist circumference (WC), triceps skin folds (TSF) and arm muscle area (AMA) were performed.

RESULTS

The plasma alpha-tocopherol levels increased from 7.9 microM (0.32-18.4) to 14.2 microM (1.22-23.8) after the supplementation (P = 0.02). The mean concentration of LDL(-) was reduced from 570.9 microg/mL (225.6-1241.0) to 169.1 microg/mL (63.6-621.1) (P < 0.001). The anti-LDL(-) IgG auto-antibodies did not change significantly after the supplementation. The alpha-tocopherol supplementation also reduced the total cholesterol and LDL-C levels in these patients, from 176 +/- 42.3 mg/dL to 120 +/- 35.7 mg/dL (P < 0.05) and 115.5 +/- 21.4 mg/dL to 98.5 +/- 23.01 mg/dL (P < 0.001), respectively.

CONCLUSION

The oral administration of alpha-tocopherol in HD patients resulted in a significant decrease in the LDL(-), total cholesterol and LDL-C levels. This effect may favour a reduction in cardiovascular risk in these patients, but a larger study is required to confirm an effect in this clinical setting.

Racial and survival paradoxes in chronic kidney disease

Most of the 20 million people in the US with chronic kidney disease (CKD) die before commencing dialysis. One of every five dialysis patients dies each year in the US. Although cardiovascular disease is the most common cause of death among patients with CKD, conventional cardiovascular risk factors such as hypercholesterolemia, hypertension and obesity are paradoxically associated with better survival in hemodialysis populations. Emerging data indicate the existence of this 'reverse epidemiology' in earlier stages of CKD. There are also paradoxical relationships between outcomes and race and ethnicity. For example, the survival rate of African American dialysis patients seems to be superior to that of whites on dialysis. Paradoxes-within-paradoxes have been detected among Hispanic and Asian American CKD patients. These survival paradoxes might evolve and change over the natural course of CKD progression as a result of the time differentials of competing risk factors and the overwhelming impact of malnutrition, inflammation and wasting. Reversal of the reverse epidemiology as a result of successful kidney transplantation underscores the role of nutritional status and kidney function in engendering these paradoxes. The observation of paradoxes and their reversal might lead to the formulation of new paradigms and management strategies to improve the survival of patients with CKD. Such movement away from the use of targets set on the basis of data gathered in general populations (e.g. the Framingham cohort) would be a major paradigm shift in clinical medicine and public health.

The impact of haemodialysis-associated variables on lipid profile in Egyptian haemodialysis population

INTRODUCTION

Haemodialysis (HD) patients appear to have particular susceptibility for cardiovascular (CV) diseases with lipid abnormalities among its significant contributors. However, there is controversy concerning the combined effect on lipid constituents during HD of the three commonly used variables; the type of heparin, dialysis membrane and the constituent of dialysate buffer bases. Consequently, this controlled prospective study was thought of.

PATIENTS

Randomly 63 patients were assigned from Urology and Nephrology haemodialysis (HD) unit, Mansoura, Egypt for the planned study. Their mean age was 45.79 +/- 13.11 years. Fourteen patients with end-stage renal disease (ESRD) served as control group for the remaining 49 HD patients. They were subdivided according to the HD duration (< and > 1 year), anticoagulant used (unfractionated [UFH] and low-molecular weight heparin [LMWH, Enoxaparin), membrane type (Hemophane [HP] and polysulfone [PS] membrane) and dialysate buffer bases (bicarbonate versus acetate based).

METHODS

Determining the fasting lipid value of total cholesterol (TC) and triglycerides (TG) as well as lipoproteins including low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and lipoprotein (a) [Lp (a)] was completed.

RESULTS

Bicarbonate dialysate was associated with significantly lower TG (134.7 +/- 11 mg/dl vs. 153 +/- 14 mg/dl, p = 0.004), higher HDL-C (33.1 +/- 3 vs. 28.3 +/- 2, p = 0.0002) and subsequently better atherosclerosis risk ratio [TC/HDL-C (ARR)] (6.02 +/- 0.09 vs. 5.3 +/- 0.9, p = 0.001) despite its insignificant effect on TC and LDL-C. However, logarithm (log) Lp (a) level was significantly higher (1.92 +/- 0.05 vs. 1.82 +/- 0.04 p = 0.001) in comparison with acetate dialysate. Membrane type was not influential in those dialyzed for < 1 year before intervention while after a year of HD, PS (n = 11) compared to HP filters (n = 11) significantly lowered TC (151.7 +/- 16 vs. 172.6 +/- 12, p = 0.003), TG (127.8 +/- 15 vs. 155.7 +/- 15, p = 0.004), LDL-C (122.1 +/- 5 vs. 130.6 +/- 7, p = 0.006) levels as well as ARR (5.9 +/- 0.5 vs. 5.4 +/- 0.3, p = 0.02). Likewise was the reduction in log Lp (a) (1.9 +/- 0.03 vs. 1.8 +/- 0.04, p = 0.002) with insignificant effect on HDL-C. After 6 months, Enoxaparin caused significant improvement of TC (0.0004), TG (p = 0.018), LDL-C (p = 0.006), HDL-C (0.041) and Lp (a) (0.047) compared to UFH. Patients who continued on Enoxaparin for 3 more months displayed an even better attenuation in most of lipid parameters whilst continuation of UFH was insignificant. Switching few patients (n = 4) from UFH to LMWH for 3 months resulted in significant lowering of TC (153 +/- 7 vs. 177.7 +/- 3, p = 0.01), TG (127.5 +/- 5 vs. 137.3 +/- 4, p = 0.03) and LDL-C (124.7 +/- 5 vs. 127.5 +/- 5, p = 0.005). However, switching equal number of patients from LMWH to UFH caused no significant change.

CONCLUSION

Dyslipidaemia in Egyptian haemodialysis patients was improved when bicarbonate-based haemodialysis, the use of polysulfone membrane, and more so when the low-molecular weight heparin Enoxaparin were used.

Association between serum lipids and survival in hemodialysis patients and impact of race

Despite the enormous cardiovascular disease epidemic among maintenance hemodialysis (MHD) patients, total hypercholesterolemia seems paradoxically to be associated with better survival. It was hypothesized that similar paradoxic associations also exist for serum LDL, HDL, and triglycerides. A 3-yr (July 2001 through June 2004) cohort of 15,859 MHD patients was studied in the United States from DaVita dialysis clinics where lipid profile was measured in at least 50% of all outpatients during a given calendar quarter. Cox proportional hazard models were adjusted for case mix and surrogates of malnutrition-inflammation complex. Both total and LDL hypercholesterolemia showed a paradoxic association with better survival. Hypertriglyceridemia (>200 mg/dl) also showed a similar trend, but serum HDL cholesterol did not have any clear association with survival. The association between a low serum LDL <70 mg/dl, which was prevalent among almost 50% of all MHD patients, and a higher all-cause death risk was robust to multivariate adjustment. In the subgroup analyses, these paradoxic associations persisted among most subgroups, although they tended to be stronger among hypoalbuminemic (<3.8 mg/dl) patients and those with a lower dietary protein intake (<1 g/kg per d). However, in black patients, a high serum LDL (>100 mg/ml) was associated with adjusted cardiovascular death hazard ratio of 1.94 (95% confidence interval 1.12 to 2.38; P = 0.02). Despite inverse associations between hyperlipidemia and survival, black MHD patients with high LDL show almost two-fold increase in cardiovascular death risk. Although these associations may not be causal, they call into question whether specific subgroups of dialysis patients are better targets for cholesterol-lowering therapy.

The kidney disease wasting: Inflammation, oxidative stress, and diet-gene interaction

The 350,000 maintenance hemodialysis (MHD) patients in the United States have an unacceptably high mortality rate of >20%/year. Almost half of all deaths are assumed to be cardiovascular. Markers of kidney disease wasting (KDW) such as hypoalbuminemia, anorexia, body weight and fat loss, rather than traditional cardiovascular risk factors, appear to be the strongest predictors of early death in these patients. The KDW is closely related to oxidative stress (SOX). Such SOX markers as serum myeloperoxidase are associated with pro-inflammatory cytokines and poor survival in MHD patients. Identifying the conditions that modulate the KDW/SOX-axis may be the key to improving outcomes in MHD patients. Dysfunctional lipoproteins such as a higher ratio of the high-density lipoprotein inflammatory index (HII) may engender or aggravate the KDW, whereas functionally intact or larger lipoprotein pools, as in hypercholesterolemia and obesity, may mitigate the KDW in MHD patients. Hence, a reverse epidemiology or "bad-gone-good" phenomenon may be observed. Diet and gene and their complex interaction may lead to higher proportions of pro-inflammatory or oxidative lipoproteins such as HII, resulting in the aggravation of the SOX and inflammatory processes, endothelial dysfunction, and subsequent atherosclerotic cardiovascular disease and death in MHD patients. Understanding the factors that modulate the KDW/SOX complex and their associations with genetic polymorphism, nutrition, and outcomes in MHD patients may lead to developing more effective strategies to improve outcomes in this and the 20 to 30 million Americans with chronic disease states such as individuals with chronic heart failure, advanced age, malignancies, AIDS, or cachexia.

Epidemiology of dialysis patients and heart failure patients

The epidemiology of maintenance dialysis patients and heart failure patients has striking similarities. Both groups have a high prevalence of comorbid conditions, a high hospitalization rate, a low self-reported quality of life, and an excessively high mortality risk, mostly because of cardiovascular causes. Observational studies in both dialysis and heart failure patients have indicated the lack of a significant association between the traditional cardiovascular risk factors and mortality, or the existence of a paradoxic or reverse association, in that obesity, hypercholesterolemia, and hypertension appear to confer survival advantages. The time discrepancy between the 2 sets of risk factors, that is, overnutrition (long-term killer) versus undernutrition (short-term killer) may explain the overwhelming role of malnutrition, inflammation, and cachexia in causing the reverse epidemiology, which may exist in more than 20 million Americans. We have reviewed the opposing views about the concept of reverse epidemiology in dialysis and heart failure patients, the recent Die Deutsche Diabetes Dialyze study findings, and the possible role of racial disparities. Contradictory findings on hyperhomocysteinemia in dialysis patients are reviewed in greater details as a possible example of publication bias. Additional findings related to intravenous iron and serum ferritin, calcium, and leptin levels in dialysis patients may enhance our understanding of the new paradigm. The association between obesity and increased death risk in kidney transplanted patients is reviewed as an example of the reversal of reverse epidemiology. Studying the epidemiology of dialysis patients as the archetypical population with such paradoxic associations may lead to the development of population-specific guidelines and treatment strategies beyond the current Framingham cardiovascular risk factor paradigm.