Effect of lipid-lowering dietary recommendations on the nutritional intake and lipid profiles of chronic peritoneal dialysis and hemodialysis patients

Dietary Lipids and Dyslipidemia in Chronic Kidney Disease

The progression of chronic kidney disease (CKD) leads to altered lipid metabolism. CKD patients exhibit high blood triglyceride (TG) levels, reduced concentrations and functionality of high-density lipoproteins (HDL), and elevated levels of atherogenic small, dense, low-density lipoproteins (sdLDL). Disorders of lipid metabolism and other metabolic disturbances place CKD patients at high risk for cardiovascular disease (CVD). Extensive evidence supports the cardioprotective effects of unsaturated fatty acids, including their beneficial effect on serum cholesterol and TG levels. Dietary lipids might therefore be especially important in the nutritional management of CKD. We review current dietary recommendations for fat intake by CKD patients and suggest potential nutritional interventions by emphasizing dietary lipids that might improve the blood lipid profile and reduce cardiovascular risk in CKD.

Egg Intake in Chronic Kidney Disease

Patients with chronic kidney disease (CKD) are often instructed to adhere to a renal-specific diet depending on the severity and stage of their kidney disease. The prescribed diet may limit certain nutrients, such as phosphorus and potassium, or encourage the consumption of others, such as high biological value (HBV) proteins. Eggs are an inexpensive, easily available and high-quality source of protein, as well as a rich source of leucine, an essential amino acid that plays a role in muscle protein synthesis. However, egg yolk is a concentrated source of both phosphorus and the trimethylamine N-oxide precursor, choline, both of which may have potentially harmful effects in CKD. The yolk is also an abundant source of cholesterol which has been extensively studied for its effects on lipoprotein cholesterol and the risk of cardiovascular disease. Efforts to reduce dietary cholesterol to manage dyslipidemia in dialysis patients (already following a renal diet) have not been shown to offer additional benefit. There is a paucity of data regarding the impact of egg consumption on lipid profiles of CKD patients. Additionally, egg consumption has not been associated with the risk of developing CKD based on epidemiological studies. The egg yolk also contains bioactive compounds, including lutein, zeaxanthin, and vitamin D, which may confer health benefits in CKD patients. Here we review research on egg intake and CKD, discuss both potential contraindications and favorable effects of egg consumption, and describe the need for further research examining egg intake and outcomes in the CKD and end-stage renal disease population.

Nutrition Interventions in Chronic Kidney Disease

Dietary modification is recommended in the management of chronic kidney disease (CKD). Individuals with CKD often have multiple comorbidities, such as high blood pressure, diabetes, obesity, and cardiovascular disease, for which dietary modification is also recommended. As CKD progresses, nutrition plays an important role in mitigating risk for cardiovascular disease and decline in kidney function. The objectives of nutrition interventions in CKD include management of risk factors, ensuring optimal nutritional status throughout all stages of CKD, preventing buildup of toxic metabolic products, and avoiding complications of CKD. Recommended dietary changes should be feasible, sustainable, and suited for patients' food preferences and clinical needs.

Nutrition prescription to achieve positive outcomes in chronic kidney disease: a systematic review

In Chronic Kidney Disease (CKD), management of diet is important in prevention of disease progression and symptom management, however evidence on nutrition prescription is limited. Recent international CKD guidelines and literature was reviewed to address the following question “What is the appropriate nutrition prescription to achieve positive outcomes in adult patients with chronic kidney disease?” Databases included in the search were Medline and CINAHL using EBSCOhost search engine, Embase and the Cochrane Database of Systematic Reviews published from 2000 to 2009. International guidelines pertaining to nutrition prescription in CKD were also reviewed from 2000 to 2013. Three hundred and eleven papers and eight guidelines were reviewed by three reviewers. Evidence was graded as per the National Health and Medical Research Council of Australia criteria. The evidence from thirty six papers was tabulated under the following headings: protein, weight loss, enteral support, vitamin D, sodium, fat, fibre, oral nutrition supplements, nutrition counselling, including protein and phosphate, nutrients in peritoneal dialysis solution and intradialytic parenteral nutrition, and was compared to international guidelines. While more evidence based studies are warranted, the customary nutrition prescription remains satisfactory with the exception of Vitamin D and phosphate. In these two areas, additional research is urgently needed given the potential of adverse outcomes for the CKD patient.

HMG CoA reductase inhibitors (statins) for dialysis patients

BACKGROUND

Cardiovascular disease accounts for more than half the number of deaths among dialysis patients. The role of HMG CoA reductase inhibitors (statins) in the treatment of dyslipidaemia in dialysis patients is unclear and their safety has not been established.

OBJECTIVES

To assess the benefits and harms of statins in peritoneal dialysis (PD) and haemodialysis patients (HD).

SEARCH STRATEGY

We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled trials (CENTRAL, in The Cochrane Library), the Cochrane Renal Group's specialised register and handsearched reference lists of textbooks, articles and scientific proceedings.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs comparing statins with placebo, no treatment or other hypolipidaemic agents in dialysis patients.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. Statistical analyses were performed using the random effects model after testing for heterogeneity. The results were expressed as mean difference (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CI).

MAIN RESULTS

Fourteen studies (2086 patients) compared statins versus placebo or other lipid lowering agents. Compared to placebo, statins did not decrease all-cause mortality (10 studies, 1884 patients; RR 0.95, 95% CI 0.86 to 1.06) or cardiovascular mortality (9 studies, 1839 patients: RR 0.96, 95% CI 0.65 to 1.40). There was a lower incidence of nonfatal cardiovascular events with statins compared to placebo in haemodialysis patients (1 study, 1255 patients; RR 0.86, 95% CI 0.74 to 0.99). Compared with placebo, statin use was associated with a significantly lower end of treatment average total cholesterol (14 studies, 1823 patients; MD -42.61 mg/dL, 95% CI -53.38 to -31.84), LDL cholesterol (13 studies, 1801 patients; MD -43.06 mg/dL, 95% CI -53.78 to -32.35) and triglycerides (14 studies, 1823 patients: MD -24.01 mg/dL, 95% CI -47.29 to -0.72). There was similar occurrence of rhabdomyolysis and elevated liver function tests with statins in comparison to placebo.

AUTHORS' CONCLUSIONS

Statins decreased cholesterol levels in dialysis patients similar to that of the general population. With the exception of one study, studies were of short duration and therefore the efficacy of statins in decreasing the mortality rate is still unclear. Statins appear to be safe in this high-risk population. Ongoing studies should provide more insight about the efficacy of statins in reducing mortality rates in dialysis patients.

HMG CoA reductase inhibitors (statins) for dialysis patients

BACKGROUND

Cardiovascular disease accounts for more than half the number of deaths among dialysis patients. The role of HMG CoA reductase inhibitors (statins) in the treatment of dyslipidaemia in dialysis patients is unclear and their safety has not been established.

OBJECTIVES

To assess the benefits and harms of statins in peritoneal dialysis (PD) and haemodialysis patients (HD).

SEARCH STRATEGY

We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled trials (CENTRAL, in The Cochrane Library), the Cochrane Renal Group's specialised register and handsearched reference lists of textbooks, articles and scientific proceedings.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs comparing statins with placebo, no treatment or other hypolipidaemic agents in dialysis patients.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. Statistical analyses were performed using the random effects model after testing for heterogeneity. The results were expressed as mean difference (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CI).

MAIN RESULTS

Fourteen studies (2086 patients) compared statins versus placebo or other lipid lowering agents. Compared to placebo, statins did not decrease all-cause mortality (10 studies, 1884 patients; RR 0.95, 95% CI 0.86 to 1.06) or cardiovascular mortality (9 studies, 1839 patients: RR 0.96, 95% CI 0.65 to 1.40). There was a lower incidence of nonfatal cardiovascular events with statins compared to placebo in haemodialysis patients (1 study, 1255 patients; RR 0.86, 95% CI 0.74 to 0.99). Compared with placebo, statin use was associated with a significantly lower end of treatment average total cholesterol (14 studies, 1823 patients; MD -42.61 mg/dL, 95% CI -53.38 to -31.84), LDL cholesterol (13 studies, 1801 patients; MD -43.06 mg/dL, 95% CI -53.78 to -32.35) and triglycerides (14 studies, 1823 patients: MD -24.01 mg/dL, 95% CI -47.29 to -0.72). There was similar occurrence of rhabdomyolysis and elevated liver function tests with statins in comparison to placebo.

AUTHORS' CONCLUSIONS

Statins decreased cholesterol levels in dialysis patients similar to that of the general population. With the exception of one study, studies were of short duration and therefore the efficacy of statins in decreasing the mortality rate is still unclear. Statins appear to be safe in this high-risk population. Ongoing studies should provide more insight about the efficacy of statins in reducing mortality rates in dialysis patients.

Analysis of dyslipidemia in patients on chronic hemodialysis in Catalonia

Chronic hemodialysis patients show a high incidence and prevalence of cardiovascular disease of multifactorial etiology and an association between dyslipidemia and accelerated atherosclerosis. We analyzed characteristics of dyslipidemia in 1824 hemodialysis patients (59% men; mean age 65 +/- 15 years) in Catalonia and identified risk factors by logistic regression. Prevalence of dyslipidemia was high (63%). Most frequent lipid alterations were decreased HDL cholesterol (40%), hypertriglyceridemia (31%) and hypercholesterolemia (19%). Total cholesterol/HDL ratio was elevated in 23%. Body mass index (OR 1.08; 95% CI 1.05-1.11), diabetes mellitus (1.4; 1.09-1.79), ischemic heart disease (1.38, 1.08-1.75) and stroke (1.30; 1.0-1.69) were independent factors associated with dyslipidemia. Lengthy time (> 7 years) on dialysis (0.77; 0.59-0.99) and female sex (0.78; 0.64-0.96) were independent protective factors. A significant reduction in the risk of developing dyslipidemia was observed after the age of 50. Lipid-lowering drug use was low (19%), with statins being the most frequent (83%). The percentage of patients reaching target LDL levels according to individual cardiovascular risk (ATPIII) was unsatisfactory, particularly in high risk patients (52%). In light of the high prevalence of dyslipidemia and low adherence to target LDL goals, we conclude that strict control of dyslipidemia should be included in cardiovascular risk prevention strategies for chronic hemodialysis patients.

Comparison of intermittent with continuous simvastatin treatment in hypercholesterolemic patients with end stage renal failure

Coronary artery disease is the most important cause of morbidity and mortality in patients with end-stage renal failure (RF). Hypercholesterolemia is an important risk factor for coronary heart disease. Patients with chronic renal failure (CRF) have difficulties in compliance with their care and treatment. Intermittent simvastatin treatment may help to increase compliance and can be a treatment alternative in patients with CRF at risk of coronary artery disease. We investigated the effects of simvastatin and compared intermittent with continuous simvastatin treatment in hypercholesterolamic patients with CRF. The study group included 40 of 422 CRF patients on dialysis in our clinic. The inclusion criterion was low density lipoprotein cholesterol (LDL-C) of 130 mg/dL or more. Twenty patients received simvastatin 10 mg/day (continuous group) and 20 patients received simvastatin 20 mg three times a week (only dialysis days- intermittent group) for four months. Nineteen patients served as controls and they were given a prescribed diet only. Total cholesterol (TC) and LDL-C decreased markedly in patients receiving intermittent and continuous simvastatin compared to controls. Continuous simvastatin decreased TC by 23% (P < 0.001) and LDL-C by 39% (P < 0.001). Intermittent simvastatin decreased TC by 26% (P < 0.001) and LDL-C by 40% (P < 0.001). The atherogenic index ratios in both the continuous and intermittent groups (TC/High density lipoprotein-cholesterol (HDL-C) and LDL-C/HDL-C) decreased significantly. There was no significant difference in patient compliance between the two groups. Intermittent simvastatin is as effective and reliable as continuous simvastatin treatment and can be an alternative treatment in hypercholesterolemic patients on dialysis.

Protein and energy nutrition among adult patients treated with chronic peritoneal dialysis

Protein-energy malnutrition (PEM) in adult patients treated with chronic peritoneal dialysis (CPD), which is highly prevalent and frequently severe in its manifestation, poses a significant therapeutic dilemma. The causes of PEM include inflammation, low nutrient intake, nutrient losses during dialysis, metabolic acidemia, coexisting illnesses, and possibly the endocrine disorders of uremia. Treatment strategies for PEM in CPD patients include the following: attempt to treat the potentially reversible causes of anorexia, increase nutrient intake (by nutritional counseling, oral food supplements, consideration of appetite stimulants and intraperitonial amino acid solutions), and the correction of metabolic acidosis. Coexisting illnesses engendering PEM should be treated. Experimental evidence suggests that such agents as anabolic steroids, human growth hormone, insulin-like growth factor-I, and L-carnitine may engender positive protein balance in these individuals. Finally, the use of anti-inflammatory agents to improve the nutritional status of malnourished CPD patients remains to be defined. There is a need to carry out clinical trials that examine whether an improvement in the nutritional status of CPD patients is associated with an improvement in their mortality, morbidity and/or quality of life.

Congestive heart failure in patients with chronic kidney disease and on dialysis

CHF is highly prevalent in ESRD and is a leading cause of death in such patients. Hypertension, renal anemia, and comorbid conditions such as coronary artery disease are particularly important risk factors for CHF in ESRD. Dialysis hypotension may be a marker of poor prognosis in such persons. Recent studies suggest that lipid peroxidation and L-carnitine deficiency may contribute to CHF in some patients with ESRD. All forms of renal replacement therapy are capable of ameliorating symptoms of CHF, but their effect on cardiovascular mortality has not been firmly established. Drug therapy, particularly angiotensin-converting enzyme inhibitors and beta-adrenergic receptor blockers, is under-used in patients with ESRD and CHF. Heart/kidney transplantation may be a viable option for some patients with advanced CHF and ESRD.

Association of fish intake and survival in a cohort of incident dialysis patients

Multiple studies in the general population have shown cardioprotective and survival benefits associated with dietary fish intake, but little is known about outcomes associated with dietary fish intake in patients with chronic renal failure. We investigated fish consumption and survival in 216 incident dialysis patients. Fish consumption was identified in a 24-hour dietary recall and a 3-day food diary collected at baseline (near treatment start) and a 3-day food diary collected 1 year later. Patients who reported fish intake had higher average serum albumin levels at baseline than patients who did not report fish intake. Patient survival was followed up for an average of 3 years from baseline. In univariate Cox regression models, younger age, black race, peritoneal dialysis rather than hemodialysis as initial treatment modality, absence of cardiovascular comorbidity, higher self-assessed physical functioning, and fish consumption were significantly associated with patient survival. A multivariable Cox proportional hazards regression analysis showed that dietary fish consumption independently predicted patient survival, controlling for all other variables in the model. In multivariable analysis, patients who were younger, black, and had higher mental health scores at baseline also had a significantly decreased mortality risk. Patients who reported fish consumption were approximately 50% less likely to die during the study interval. Health outcomes associated with fish consumption merit continued study in patients with chronic renal failure.

Accelerated atherosclerosis, dyslipidemia, and oxidative stress in end-stage renal disease

Premature atherosclerosis is a major cause of morbidity and mortality in end-stage renal disease patients. Dyslipidemia and increased oxidative stress contribute to premature atherogenesis in these patients. The dyslipidemia of end-stage renal disease consists of both quantitative and qualitative abnormalities in serum lipoproteins. Qualitative changes include hypertriglyceridemia (increased remnant lipoproteins), low high-density lipoprotein-cholesterol, and increased lipoprotein (a). In addition to quantitative changes, lipoproteins in end-stage renal disease undergo compositional and qualitative changes that make them pro-atherogenic, such as various modifications of apolipoprotein B, including oxidation, and modification by advanced glycation end-products. The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors and low-dose fibrates could be effective therapies for lipid disorders. The best evidence for increased oxidative stress in end-stage renal disease is the demonstration of increased plasma F2-isoprostanes. Confirmation of the positive findings with high-dose alpha-tocopherol in the Secondary Prevention with Antioxidants of Cardiovascular Disease in End-stage Renal Disease Study is urgently needed. Clinical trials with statins and other drugs that improve dyslipidemia also need to be undertaken. These therapies could clearly lead to a reduction in cardiovascular morbidity and mortality in these patients.

Safety and efficacy of simvastatin in hypercholesterolemic patients undergoing chronic renal dialysis

Dyslipidemia is universal but hypercholesterolemia per se is present in around 50% of dialysis patients. Although dietary therapy is of benefit in some, the majority require drug therapy. We compared the efficacy and safety of simvastatin plus an optimized lipid-lowering dialysis diet with placebo plus diet in a randomized, double-blind trial stratified for dialysis modality. Patients treated with hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD) for at least 9 months and with serum non-high-density lipoprotein (HDL) cholesterol greater than 135 mg/dL, low-density lipoprotein (LDL) greater than 116 mg/dL, and triglyceride less than 600 mg/dL after a 6-week dietary treatment phase and an 8-week diet plus placebo run-in phase, were enrolled in the 24-week double-blind treatment phase. Fifty-seven patients (16 men, 41 women, median age 63 years, range 22-75 yr) were randomized 2:1 to diet plus 5 mg/day simvastatin (n = 38: 22 HD, 16 CAPD) or diet plus placebo (n = 19: 12 HD, 7 CAPD) for 24 weeks. Dose was doubled bimonthly (maximum 20 mg/day) if non-HDL cholesterol was greater than 135 mg/dL. Forty-two patients (73.7%) completed the trial. Comparing baseline and 24 weeks, simvastatin (median 10 mg/day) was significantly more effective than placebo in reducing serum non-HDL cholesterol concentrations. For HD, the median percentage changes for total cholesterol (TC) (simvastatin versus placebo) were -21.4% and -12.1% (P = 0.011), respectively; for LDL cholesterol, -33.0% and -8.8% (P = 0.023); for non-HDL cholesterol, -25.2% and -14.0% (P = 0.008); and for TC:HDL, -17.65% and -1.67% (P = 0.008). For CAPD, changes for TC were -22.1% and -1.5% (P = 0.003), respectively; for LDL, -36.4% and 0.0% (P = 0.001); for non-HDL cholesterol, -24.9% and -3.6% (P = 0.002); and for TC:HDL ratio, -21.49% and +9.74% (P = 0.045). Changes with CAPD in apolipoprotein (Apo) A1 were -4.7% and +4.0% (P = 0.031); and for ApoB, -19.9% and +2.6%, respectively (P = 0.031). There were no significant changes in ApoA1 or ApoB with HD. Compared with placebo, triglyceride levels fell 10.2% with HD and 6.2% with CAPD. HDL cholesterol was unchanged with HD but rose 8.5% with CAPD. These trends, however, did not reach statistical significance (P > 0.05). There was no effect on Lp (a). The incidence of clinical and laboratory adverse experiences were not increased in the simvastatin-treated patients compared with placebo. Simvastatin appears to be a safe and effective treatment for the reduction of serum non-HDL cholesterol levels in both HD and, particularly, CAPD patients.