Elevated high-density lipoprotein cholesterol and cardiovascular mortality in maintenance hemodialysis patients

Association of serum lipid levels over time with survival in incident peritoneal dialysis patients

BACKGROUND

The association of dyslipidemia with mortality has not been fully evaluated in patients on peritoneal dialysis (PD). Moreover, changes in lipids levels over time and associated death risk have not yet been studied in this population.

OBJECTIVE

We studied the association of time-updated serum lipid concentrations with all-cause and cardiovascular (CV) mortalities in a 10-year cohort of 749 incident PD patients.

METHODS

Association was assessed using time-varying Cox proportional hazard regression models with adjustment for multiple variables including statin therapy.

RESULTS

During a median follow-up of 36 (interquartile range, 21-61) months, 273 all-cause and 107 CV deaths occurred. Compared with those with total cholesterol (TC) of 180 to <210 or low-density lipoprotein cholesterol (LDL-C) of 100 to <130 mg/dL, hazard ratios (95% confidence interval) of the lowest TC (<150 mg/dL) and LDL-C (<70 mg/dL) were 2.32 (1.61-3.35) and 2.02 (1.45-2.83) for all-cause mortality and 1.87 (1.04-3.37) and 1.92 (1.13-3.26) for CV mortality, respectively. Lower triglyceride (<100 mg/dL) and high-density lipoprotein cholesterol (<30 mg/dL) levels were associated with higher all-cause mortality (1.66 [1.11-2.47] and 1.57 [1.08-2.29]) but not with CV mortality.

CONCLUSIONS

Contrary to the general population, lower TC and LDL-C levels over time were significantly associated with both worse survival and increased CV mortality in incident PD patients. Although lower triglyceride and high-density lipoprotein cholesterol concentrations were associated with significantly higher all-cause mortality, they failed to show any clear association with CV mortality. The underlying mechanisms responsible for this apparent paradox await further investigations.

The atherogenic index of plasma and the risk of mortality in incident dialysis patients: Results from a nationwide prospective cohort in Korea

Background

The atherogenic index of plasma (AIP), which is the logarithmic ratio of triglyceride (TG) to high-density lipoprotein cholesterol (HDL-C), had a linear relationship with clinical outcomes in the general population. However, the association of each lipid profile, TG and HDL-C, with survival was not straightforward in dialysis patients. This non-linear association led us to further investigate the prognostic impact of the AIP in these patients.

Methods

From a nationwide prospective cohort, 1,174 incident dialysis patients were included. Patients were categorized into quintiles according to the AIP. An independent association of the AIP with all-cause and cardiovascular mortality was determined.

Results

During a mean follow-up duration of 33.2 months, 170 patients (14.5%) died, and cardiovascular death was observed in 55 patients (4.7%). Multivariate Cox analyses revealed that the lowest (quintile 1, hazard ratio [HR] = 1.76, 95% confidence interval [CI] = 1.02–3.03) and the highest (quintile 5, HR = 2.15, 95% CI = 1.26–3.65) AIP groups were significantly associated with higher all-cause mortality compared to patients in quintile 3 (reference group). In terms of cardiovascular mortality, only the highest AIP group (quintile 5, HR = 2.59, 95% CI = 1.06–6.34) was significantly associated with increased risk of mortality. Sensitivity analyses showed that a U-shaped association between the AIP and all-cause mortality remained significant in non-diabetic and underweight to normal body mass index patients.

Conclusions

Both the highest and the lowest AIP groups were independently associated with all-cause mortality, showing a U-shaped association. It suggested further studies are needed to identify targets and subgroups that can benefit from intervention of the AIP in incident dialysis patients.

Association of Serum Triglyceride to HDL Cholesterol Ratio with All-Cause and Cardiovascular Mortality in Incident Hemodialysis Patients

BACKGROUND AND OBJECTIVES

Elevated serum triglyceride/HDL cholesterol (TG/HDL-C) ratio has been identified as a risk factor for cardiovascular (CV) disease and mortality in the general population. However, the association of this important clinical index with mortality has not been fully evaluated in patients with ESRD on maintenance hemodialysis (MHD). We hypothesized that the association of serum TG/HDL-C ratio with all-cause and CV mortality in patients with ESRD on MHD is different from the general population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied the association of serum TG/HDL-C ratio with all-cause and CV mortality in a nationally representative cohort of 50,673 patients on incident hemodialysis between January 1, 2007 and December 31, 2011. Association of baseline and time-varying TG/HDL-C ratios with mortality was assessed using Cox proportional hazard regression models, with adjustment for multiple variables, including statin therapy.

RESULTS

During the median follow-up of 19 months (interquartile range, 11-32 months), 12,778 all-cause deaths and 4541 CV deaths occurred, respectively. We found that the 10th decile group (reference: sixth deciles of TG/HDL-C ratios) had significantly lower risk of all-cause mortality (hazard ratio, 0.91 [95% confidence interval, 0.83 to 0.99] in baseline and 0.86 [95% confidence interval, 0.79 to 0.94] in time-varying models) and CV mortality (hazard ratio, 0.83 [95% confidence interval, 0.72 to 0.96] in baseline and 0.77 [95% confidence interval, 0.66 to 0.90] in time-varying models). These associations remained consistent and significant across various subgroups.

CONCLUSIONS

Contrary to the general population, elevated TG/HDL-C ratio was associated with better CV and overall survival in patients on hemodialysis. Our findings provide further support that the nature of CV disease and mortality in patients with ESRD is unique and distinct from other patient populations. Hence, it is vital that future studies focus on identifying risk factors unique to patients on MHD and decipher the underlying mechanisms responsible for poor outcomes in patients with ESRD.

Could high-density lipoprotein cholesterol predict increased cardiovascular risk?

PURPOSE OF REVIEW

Serum high-density lipoprotein (HDL) is considered to be protective against cardiovascular disease. However, there is emerging evidence that under certain conditions the HDL molecule can become dysfunctional and proinflammatory, paradoxically leading to increased risk of cardiovascular disease. This review will provide a brief outline of the potential mechanisms by which HDL can become atherogenic and summarize some of the clinical evidence on this topic.

RECENT FINDINGS

HDL metabolism, structure, and function in addition to its level can be profoundly altered under conditions of marked oxidative stress and chronic inflammation. These abnormalities, in turn, lead to impaired reverse cholesterol transport, increased systemic oxidative stress/inflammation, and endothelial dysfunction that subsequently may contribute to atherogenesis and progression of cardiovascular disease.

SUMMARY

Association of serum HDL cholesterol level with outcomes is not only dependent on its serum concentration but also on the qualities/properties of this lipoprotein at a given point in time. Hence, it is essential that future studies examining association of HDL with risk of cardiovascular disease take into account the complexities of HDL metabolism and function and address the impact of the HDL particle as a whole (quantity as well as various properties) on atherosclerosis and cardiovascular outcomes.

Risk factors for mortality in patients undergoing hemodialysis: A systematic review and meta-analysis

BACKGROUND

No consensus exists regarding the factors influencing mortality in patients undergoing hemodialysis (HD). This meta-analysis aimed to evaluate the impact of various patient characteristics on the risk of mortality in such patients.

METHODS

PubMed, Embase, and Cochrane Central were searched for studies evaluating the risk factors for mortality in patients undergoing HD. The factors included age, gender, diabetes mellitus (DM), body mass index (BMI), previous cardiovascular disease (CVD), HD duration, hemoglobin, albumin, white blood cell, C-reactive protein (CRP), parathyroid hormone, total iron binding capacity (TIBC), iron, ln ferritin, adiponectin, apolipoprotein A1 (ApoA1), ApoA2, ApoA3, high-density lipoprotein (HDL), total cholesterol, hemoglobin A1c (HbA1c), serum phosphate, troponin T (TnT), and B-type natriuretic peptide (BNP). Relative risks with 95% confidence intervals were derived. Data were synthesized using the random-effects model.

RESULTS

Age (per 1-year increment), DM, previous CVD, CRP (higher versus lower), ln ferritin, adiponectin (per 10.0μg/mL increment), HbA1c (higher versus lower), TnT, and BNP were associated with an increased risk of all-cause mortality. BMI (per 1kg/m² increment), hemoglobin (per 1d/dL increment), albumin (higher versus lower), TIBC, iron, ApoA2, and ApoA3 were associated with reduced risk of all-cause mortality. Age (per 1-year increment), gender (women versus men), DM, previous CVD, HD duration, ln ferritin, HDL, and HbA1c (higher versus lower) significantly increased the risk of cardiac death. Albumin (higher versus lower), TIBC, and ApoA2 had a beneficial impact on the risk of cardiac death.

CONCLUSIONS

Multiple markers and factors influence the risk of mortality and cardiac death in patients undergoing HD.

Do HDL and LDL subfractions play a role in atherosclerosis in end-stage renal disease (ESRD) patients?

BACKGROUND

Significantly increased cardiovascular mortality in patients with chronic kidney (CKD) disease cannot be explained by traditional risk factors. Recent studies revealed that the quality of HDL and LDL cholesterol may be more important than their serum levels. The aim of this study was to assess which LDL and HDL subfractions were more abundant in end-stage renal disease (ESRD) patients and to analyse whether subfraction distribution could be associated with accelerated atherosclerotic processes.

METHODS

This study included 50 ESRD patients undergoing dialysis and 20 healthy volunteers. LDL and HDL subfractions were analysed in serum with the use of Lipoprint system. All patients had intima-media thickness (IMT) measured.

RESULTS

Statistically significant differences in subfractions between control and study group were observed in case of: HDL1 (p < 0.0001), HDL2 (p = 0.009), HDL3 (p < 0.0001), HDL4 (p = 0.003), HDL5 (p = 0.01), HDL7 (p < 0.0001), HDL8 (p < 0.0001), HDL9 (p < 0.0001), HDL10 (p < 0.0001), large HDL (p < 0.0001), HDL Small (p < 0.0001) as well as IDL-B (p = 0.014), IDLA (p = 0.011), LDL2 (p = 0.007). Significant differences were also observed in HDL and LDL subfraction distribution between haemodialysis patients with normal and increased IMT: HDL6 (p = 0.020), HDL Large (HDL1-3) (p = 0.017), HDL Intermediate (HDL4-7) (p = 0.017).

CONCLUSIONS

This study revealed that ESRD influenced HDL subfractions. In HD patients, large HDL subfractions are more abundant while small HDL fraction is more frequent in healthy persons. It failed to show the influence of end-stage disease on LDL subfraction levels. Shift in HDL subfractions might be responsible for the increased risk of atherosclerosis in CKD patients.

HDL Cholesterol Efflux Does Not Predict Cardiovascular Risk in Hemodialysis Patients

The cardioprotective effect of HDL is thought to be largely determined by its cholesterol efflux capacity, which was shown to inversely correlate with atherosclerotic cardiovascular disease in populations with normal kidney function. Patients with ESRD suffer an exceptionally high cardiovascular risk not fully explained by traditional risk factors. Here, in a post hoc analysis in 1147 patients with type 2 diabetes mellitus on hemodialysis who participated in the German Diabetes Dialysis Study (4D Study), we investigated whether the HDL cholesterol efflux capacity is predictive for cardiovascular risk. Efflux capacity was quantified by incubating human macrophage foam cells with apoB-depleted serum. During a median follow-up of 4.1 years, 423 patients reached the combined primary end point (composite of cardiac death, nonfatal myocardial infarction, and stroke), 410 patients experienced cardiac events, and 561 patients died. Notably, in Cox regression analyses, we found no association of efflux capacity with the combined primary end point (hazard ratio [HR], 0.96; 95% confidence interval [95% CI], 0.88 to 1.06; P=0.42), cardiac events (HR, 0.92; 95% CI, 0.83 to 1.02; P=0.11), or all-cause mortality (HR, 0.96; 95% CI, 0.88 to 1.05; P=0.39). In conclusion, HDL cholesterol efflux capacity is not a prognostic cardiovascular risk marker in this cohort of patients with diabetes on hemodialysis.

Low levels of high-density lipoprotein cholesterol increase the risk of incident kidney disease and its progression

Available experimental evidence suggests a role for high-density lipoprotein cholesterol (HDL-C) in incident chronic kidney disease (CKD) and its progression. However, clinical studies are inconsistent. We therefore built a cohort of 1,943,682 male US veterans and used survival models to examine the association between HDL-C and risks of incident CKD or CKD progression (doubling of serum creatinine, eGFR decline of 30% or more), or a composite outcome of ESRD, dialysis, or renal transplantation. Models were adjusted for demographics, comorbid conditions, eGFR, body mass index, lipid parameters, and statin use over a median follow-up of 9 years. Compared to those with HDL-C of 40 mg/dl or more, low HDL-C (under 30 mg/dl) was associated with increased risk of incident eGFR under 60 ml/min/1.73 m(2) (hazard ratio: 1.18; confidence interval: 1.17-1.19) and risk of incident CKD (1.20; 1.18-1.22). Adjusted models demonstrate an association between low HDL-C and doubling of serum creatinine (1.14; 1.12-1.15), eGFR decline of 30% or more (1.13; 1.12-1.14), and the composite renal end point (1.08; 1.06-1.11). Cubic spline analyses of the relationship between HDL-C levels and renal outcomes showed a U-shaped relationship, where risk was increased in lowest and highest deciles of HDL-C. Thus, a significant association exists between low HDL-C levels and risks of incident CKD and CKD progression. Further studies are needed to explain the increased risk of adverse renal outcomes in patients with high HDL-C.

Current Focuses in Serum Lipid Abnormalities in Dialysis Patients

BACKGROUND

Dyslipidemia is a common metabolic complication in patients with chronic kidney disease and is detected as changes in lipoprotein concentrations in serum.

SUMMARY

Recently, other features of lipid abnormalities have been described, such as alterations in serum n-3 polyunsaturated fatty acids, cholesterol metabolism (proportion of hepatic synthesis and intestinal absorption), and dysfunctional high-density lipoprotein.

KEY MESSAGES

Since abnormalities of these new aspects predict adverse outcomes in hemodialysis populations, they may be helpful in risk stratification of patients and could also be new targets for prevention.

HDL abnormalities in nephrotic syndrome and chronic kidney disease

Normal HDL activity confers cardiovascular and overall protection by mediating reverse cholesterol transport and through its potent anti-inflammatory, antioxidant, and antithrombotic functions. Serum lipid profile, as well as various aspects of HDL metabolism, structure, and function can be profoundly altered in patients with nephrotic range proteinuria or chronic kidney disease (CKD). These abnormalities can, in turn, contribute to the progression of cardiovascular complications and various other comorbidities, such as foam cell formation, atherosclerosis, and/or glomerulosclerosis, in affected patients. The presence and severity of proteinuria and renal insufficiency, as well as dietary and drug regimens, pre-existing genetic disorders of lipid metabolism, and renal replacement therapies (including haemodialysis, peritoneal dialysis, and renal transplantation) determine the natural history of lipid disorders in patients with kidney disease. Despite the adverse effects associated with dysregulated reverse cholesterol transport and advances in our understanding of the underlying mechanisms, safe and effective therapeutic interventions are currently lacking. This Review provides an overview of HDL metabolism under normal conditions, and discusses the features, mechanisms, and consequences of HDL abnormalities in patients with nephrotic syndrome or advanced CKD.

The effect of omega-3 on serum lipid profile in hemodialysis patients

Introduction: One of the major complications in hemodialysis patients is cardiovascular disease. Lipid abnormality is an important factor in the development of cardiovascular disease.

Objectives: To investigate the effect of omega-3 supplementation on serum lipid profile in hemodialysis patients.

Patients and Methods: This randomized clinical trial study included 2 groups of patients: those who received omega-3 supplementation (experimental group; 30 cases) and those who received placebo (control group; 30 cases). They received these for 10 weeks and serum lipid profile (triglyceride, high-density lipoprotein [HDL-C], low-density lipoprotein [LDL-C], and total cholesterol) was assessed 2 times, first before initiating supplementation and then at the end of 10-week study period.

Results: Mean (±SD) serum total cholesterol levels at the beginning was 163 (±47) mg/dL in experimental group and 143 (±25) mg/dL in control group (P> 0.05). These values decreased to 124 mg/dL and 132 mg/dL in control and experimental groups (P< 0.05). There was no significant difference of HDL-C, LDL-C, or triglyceride levels between experimental and control groups after 10 weeks of treatment.

Conclusion: Omega-3 supplementation in hemodialysis patients only showed significant decrease of serum total cholesterol level, but not other lipids.

Higher serum triglyceride to high-density lipoprotein cholesterol ratio was associated with increased cardiovascular mortality in female patients on peritoneal dialysis

BACKGROUND AND AIMS

High serum triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio has been found to be an independent predictor for cardiovascular events in the general population. We aimed to evaluate whether a high TG/HDL-C ratio was associated with an increased risk of mortality in patients on continuous ambulatory peritoneal dialysis (CAPD).

METHODS AND RESULTS

In this single-center retrospective cohort study, 1170 incident patients on peritoneal dialysis (PD) from 1 January 2007 to 31 December 2011 were recruited and followed up until 31 December 31 2013. The mean age was 47.4 ± 15.2 years, and 24.7% were diabetic. During a median of the 34.5-month follow-up period, 213 (18.2%) deaths occurred, 121 of which (56.8%) were caused by cardiovascular disease (CVD). The serum median TG/HDL-C ratio at baseline was 2.57 (range: 0.06-39.39). On multivariate Cox regression analysis, the highest quartile of the TG/HDL-C ratio (≥4.19) was associated with increased risk of all-cause mortality (hazard ratio (HR) 1.98, 95% confidence interval (CI), 1.17-3.36; P = 0.011) and CVD mortality (HR 2.28, 95% CI, 1.16-4.47; P = 0.017). For female patients, each one-unit higher baseline TG/HDL-C was associated with 13% (95% CI 1.06-1.22; P = 0.001) increased risk of CVD mortality, whereas such an association was not observed for male patients, (HR 1.00, 95% CI 0.92-1.08; P = 0.977).

CONCLUSIONS

A higher serum TG/HDL-C ratio was associated with an increased risk of all-cause and CVD mortality in PD patients. Moreover, the increased risk of CVD mortality was significantly higher in female than male PD patients.

Association of serum lipids with outcomes in Hispanic hemodialysis patients of the West versus East Coasts of the United States

BACKGROUND

Paradoxical associations exist between serum lipid levels and mortality in patients on maintenance hemodialysis (MHD) including those of Hispanic origin. However, there are significant racial and ethnic variations in patients of 'Hispanic' background. We hypothesized that clinically meaningful differences existed in the association between lipids and survival in Hispanic MHD patients on the West versus East Coast.

METHODS

We examined the survival impact of serum lipids in a 2-year cohort of 15,109 MHD patients of Hispanic origin being treated in California, Texas, representing the West versus New York, New Jersey and Florida representing the East Coast, using Cox models with various degrees of adjustments.

RESULTS

The association of serum total and HDL cholesterol with mortality follows a U-shaped pattern in Hispanic patients residing in the West. This is in contrast to Hispanic patients in the East Coast whose survival seems to improve with increasing total and HDL cholesterol levels. Elevated serum LDL levels in Hispanic patients on the West Coast are associated with a significant increase in mortality, while this association is not observed in patients residing on the East Coast.

CONCLUSIONS

Substantial differences exist in the association of serum lipids with mortality in MHD patients of Hispanic background depending on whether they reside on the West or East Coast of the United States. These geographical variances most likely reflect ethnic, racial and genetic distinctions, which are usually ignored. Future studies should take into account these critical variations in a population of patients who make up a significant portion of our society.

Residual Cardiovascular Risk in Chronic Kidney Disease: Role of High-density Lipoprotein

Although reducing low-density lipoprotein-cholesterol (LDL-C) levels with lipid-lowering agents (statins) decreases cardiovascular disease (CVD) risk, a substantial residual risk (up to 70% of baseline) remains after treatment in most patient populations. High-density lipoprotein (HDL) is a potential contributor to residual risk, and low HDL-cholesterol (HDL-C) is an established risk factor for CVD. However, in contrast to conventional lipid-lowering therapies, recent studies show that pharmacologic increases in HDL-C levels do not bring about clinical benefits. These observations have given rise to the concept of dysfunctional HDL where increases in serum HDL-C may not be beneficial because HDL loss of function is not corrected by or even intensified by the therapy. Chronic kidney disease (CKD) increases CVD risk, and patients whose CKD progresses to end-stage renal disease (ESRD) requiring dialysis are at the highest CVD risk of any patient type studied. The ESRD population is also unique in its lack of significant benefit from standard lipid-lowering interventions. Recent studies indicate that HDL-C levels do not predict CVD in the CKD population. Moreover, CKD profoundly alters metabolism and composition of HDL particles and impairs their protective effects on functions such as cellular cholesterol efflux, endothelial protection, and control of inflammation and oxidation. Thus, CKD-induced perturbations in HDL may contribute to the excess CVD in CKD patients. Understanding the mechanisms of vascular protection in renal disease can present new therapeutic targets for intervention in this population.

Latest consensus and update on protein-energy wasting in chronic kidney disease

PURPOSE OF REVIEW

Protein-energy wasting (PEW) is a state of metabolic and nutritional derangements in chronic disease states including chronic kidney disease (CKD). Cumulative evidence suggests that PEW, muscle wasting and cachexia are common and strongly associated with mortality in CKD, which is reviewed here.

RECENT FINDINGS

The malnutrition-inflammation score (KALANTAR Score) is among the comprehensive and outcome-predicting nutritional scoring tools. The association of obesity with poor outcomes is attenuated across more advanced CKD stages and eventually reverses in the form of obesity paradox. Frailty is closely associated with PEW, muscle wasting and cachexia. Muscle loss shows stronger associations with unfavorable outcomes than fat loss. Adequate energy supplementation combined with low-protein diet for the management of CKD may prevent the development of PEW and can improve adherence to low-protein diet, but dietary protein requirement may increase with aging and is higher under dialysis therapy. Phosphorus burden may lead to poor outcomes. The target serum bicarbonate concentration is normal range and at least 23 mEq/l for nondialysis-dependent and dialysis-dependent CKD patients, respectively. A benefit of exercise is suggested but not yet conclusively proven.

SUMMARY

Prevention and treatment of PEW should involve individualized and integrated approaches to modulate identified risk factors and contributing comorbidities.

Association of Adiponectin With Body Composition and Mortality in Hemodialysis Patients

BACKGROUND

In the general population, circulating adiponectin is associated with a favorable cardiovascular risk profile (eg, lower triglycerides and body fat) and decreased mortality. Hemodialysis (HD) patients have comparatively higher adiponectin concentrations, but prior studies examining the adiponectin-mortality association in this population have not accounted for body composition or shown a consistent relationship.

STUDY DESIGN

Prospective cohort study.

SETTINGS & PARTICIPANTS

We examined baseline serum adiponectin concentrations in 501 HD patients across 13 dialysis centers from the prospective MADRAD (Malnutrition, Diet, and Racial Disparities in Chronic Kidney Disease) cohort (entry period, October 2011 to February 2013; follow-up through August 2013).

PREDICTOR

Serum adiponectin concentration in tertiles (tertiles 1, 2, and 3 defined as ≤16.1, >16.1-<30.1, and ≥30.1-100.0 μg/mL, respectively). Adjustment variables included case-mix and laboratory test results (age, sex, race, ethnicity, vintage, diabetes, serum albumin, total iron-binding capacity, serum creatinine, white blood cell count, phosphate, hemoglobin, and normalized protein catabolic rate), body composition surrogates (subcutaneous, visceral, and total-body fat and lean body mass), and serum lipid levels (cholesterol, high-density lipoprotein cholesterol, and triglycerides).

OUTCOMES

All-cause mortality using survival (Cox) models incrementally adjusted for case-mix and laboratory test results.

RESULTS

Among 501 HD patients, 50 deaths were observed during 631.1 person-years of follow-up. In case-mix- and laboratory-adjusted Cox analyses, the highest adiponectin tertile was associated with increased mortality versus the lowest tertile (HR, 3.35; 95% CI, 1.50-7.47). These associations were robust in analyses that additionally accounted for body composition (HR, 3.18; 95% CI, 1.61-8.24) and lipid levels (HR, 3.64; 95% CI, 1.34-7.58).

LIMITATIONS

Residual confounding cannot be excluded.

CONCLUSIONS

Higher adiponectin level is associated with a 3-fold higher death risk in HD patients independent of body composition and lipid levels. Future studies are needed to elucidate underlying mechanisms and determine therapeutic targets associated with improved outcomes in HD patients.

Dialysis Modalities and HDL Composition and Function

Lipid abnormalities may have an effect on clinical outcomes of patients on dialysis. Recent studies have indicated that HDL dysfunction is a hallmark of ESRD. In this study, we compared HDL composition and metrics of HDL functionality in patients undergoing hemodialysis (HD) or peritoneal dialysis (PD) with those in healthy controls. We detected a marked suppression of several metrics of HDL functionality in patients on HD or PD. Compositional analysis revealed that HDL from both dialysis groups shifted toward a more proinflammatory phenotype with profound alterations in the lipid moiety and protein composition. With regard to function, cholesterol efflux and anti-inflammatory and antiapoptotic functions seemed to be more severely suppressed in patients on HD, whereas HDL-associated paraoxonase activity was lowest in patients on PD. Quantification of enzyme activities involved in HDL metabolism suggested that HDL particle maturation and remodeling are altered in patients on HD or PD. In summary, our study provides mechanistic insights into the formation of dysfunctional HDL in patients with ESRD who are on HD or PD.

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.

Triglyceride to high-density lipoprotein cholesterol ratio predicts cardiovascular outcomes in prevalent dialysis patients

Triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio, an indicator of atherogenic dyslipidemia, is a predictor of cardiovascular (CV) outcomes in the general population and has been correlated with atherosclerotic events. Whether the TG/HDL-C ratio can predict CV outcomes and survival in dialysis patients is unknown. We performed this prospective, observational cohort study and enrolled 602 dialysis patients (539 hemodialysis and 63 peritoneal dialysis) from a single center in Taiwan followed up for a median of 3.9 years. The outcomes were the occurrence of CV events, CV death, and all-cause mortality during follow-up. The association of baseline TG/HDL-C ratio with outcomes was explored with Cox regression models, which were adjusted for demographic parameters and inflammatory/nutritional markers. Overall, 203 of the patients experienced CV events and 169 patients died, of whom 104 died due to CV events. Two hundred fifty-four patients reached the composite CV outcome. Patients with higher TG/HDL-C levels (quintile 5) had a higher incidence of CV events (adjusted hazard ratio [HR] 2.03, 95% confidence interval [CI] 1.19-3.47), CV mortality (adjusted HR 1.91, 95% CI 1.07-3.99), composite CV outcome (adjusted HR 2.2, 95% CI 1.37-3.55), and all-cause mortality (adjusted HR 1.94, 95% CI 1.1-3.39) compared with the patients in quintile 1. However, in diabetic dialysis patients, the TG/HDL-C ratio did not predict the outcomes. The TG/HDL-C ratio is a reliable and easily accessible predictor to evaluate CV outcomes and survival in prevalent nondiabetic dialysis patients. ClinicalTrials.gov: NCT01457625.

Dysfunctional high-density lipoproteins in children with chronic kidney disease

OBJECTIVES

Our aim was to determine if chronic kidney disease (CKD) occurring in childhood impairs the normally vasoprotective functions of high-density lipoproteins (HDLs).

MATERIALS AND METHODS

HDLs were isolated from children with end-stage renal disease on dialysis (ESRD), children with moderate CKD and controls with normal kidney function. Macrophage response to HDLs was studied as expression of inflammatory markers (MCP-1, TNF-α, IL-1β) and chemotaxis. Human umbilical vein endothelial cells were used for expression of adhesion molecules (ICAM-1, VCAM-1, E-selectin) and adhesion. Cellular proliferation, apoptosis, and necrosis of endothelial cells were measured by MTS/PMS reagent-based assay, flow cytometry, and ELISA. Cholesterol efflux was assessed by gas chromatographic measurements of cholesterol in macrophages exposed to HDLs.

RESULTS

Compared with HDL(Control), HDL(CKD) and HDL(ESRD) heightened the cytokine response and disrupted macrophage chemotaxis. HDL(Control) reduced endothelial expression of ICAM-1, VCAM-1, E-selectin, whereas HDL(CKD) and HDL(ESRD) were less effective and showed reduced capacity to protect endothelial cells against monocyte adhesion. Compared with a dramatically enhanced endothelial proliferation following injurious stimulus by HDL(Control), neither HDL(CKD) nor HDL(ESRD) caused proliferative effects. HDLs of all three groups were equally protective against apoptosis assessed by flow cytometry and cleaved caspase-3 activity. Compared to HDL(Control), HDL(CKD) and HDL(ESRD) trended toward reduced capacity as cholesterol acceptors.

CONCLUSION

CKD in children impairs HDL function. Even in the absence of long-standing and concomitant risk factors, CKD alters specific HDL functions linked to control of inflammation and endothelial responses.