Role of nutrition for cardiovascular risk reduction in chronic kidney disease patients

Geriatric nutrition risk index is associated with renal progression, cardiovascular events and all-cause mortality in chronic kidney disease

BACKGROUND

Malnutrition is common and associated with poor outcomes in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Recently, the geriatric nutritional risk index (GNRI) was reported as a novel tool for evaluating nutritional status. However, the association between GNRI and renal outcome, cardiovascular (CVD) events, and mortality in patients with CKD remains unclear.

METHODS

A prospective cohort study with adult patients with CKD stages 1-4 was conducted at 39 centers around China starting in 2011. Patients were divided into quartiles (Q1, Q2, Q3, and Q4) according to their GNRI category.

RESULTS

A total of 2791 CKD patients within a median follow-up of 4.38 years were included. A low GNRI quartile was independently associated with progression to ESRD, CVD events, and overall mortality. Compared to that in the Q1 group (the reference group), belonging to a higher GNRI quartile significantly reduced the risk of progression to ESRD in the crude and multivariate-adjusted models. Moreover, a significant inverse association was found between those in the high GNRI quartiles and overall mortality among patients with CKD (HR 0.25; 95% CI 0.15-0.43; p = 0.0007, Q4 vs. Q1) after multivariate adjustment. In addition, there was also a significant association between GNRI and CVD events (HR 0.57; 95% CI 0.39-0.84; p = 0.005, Q4 vs. Q1). Moreover, after adjusting for other confounders, only the Q3 group remained significantly fewer CVD events (HR 0.44; 95% CI 0.19-0.98; p = 0.04).

CONCLUSIONS

These findings suggest that GNRI might be a useful prognostic tool for patients with CKD.

Dietary Intake of Proteins and Calories Is Inversely Associated With The Oxidation State of Plasma Thiols in End-Stage Renal Disease Patients

OBJECTIVES

Oxidative stress contributes to the pathogenesis of protein-energy wasting in maintenance hemodialysis (MHD) patients, but knowledge of specific effectors and mechanisms remains fragmented. Aim of the study was to define whether and how food intake is involved in the causal relationship between oxidative stress and protein-energy wasting.

METHODS

Seventy-one adult MHD patients and 24 healthy subjects (control) were studied cross-sectionally with analyses of diet record and of oxidative stress, as measured by a battery of plasma thiols including the protein sulfhydryl (-SH) group (PSH) levels (a marker of total protein-SH reducing capacity), the protein thiolation index (PTI, the ratio between disulfide, i.e., oxidized and reduced -SH groups in proteins), low molecular mass (LMM) thiols, LMM disulfides, and mixed LMM-protein disulfides. In addition, interleukin-6 (IL-6), albumin, C-reactive protein, and neutrophil gelatinase-associated lipocalin (NGAL) were measured as markers of inflammation.

RESULTS

The patients showed low energy (22.0 ± 8.4 kcal/kg/day) and adequate protein (1.0 ± 0.4 g/kg/day) intakes, high levels of cystine (CySS; patients vs.

CONTROL

113.5 [90.9-132.8] vs. 68.2 [56.2-75.7] μM), cysteinylated proteins (CySSP; 216.0 [182.8-254.0] vs. 163.5 [150.0-195.5] μM), and high PTI (0.76 [0.61-0.88] vs. 0.43 [0.40-0.54]; P < .001 in all comparisons). In patients, variation of CySSP was explained by a standard regression model (R = 0.775; P = .00001) that included significant contributions of protein intake (β = -0.361), NGAL (β = 0.387), age (β = 0.295), and albumin (β = 0.457). In the same model, variation of PTI (R = 0.624; P = .01) was explained by protein intake (β = -0.384) and age (β = 0.326) and NGAL (β = 0.311). However, when PSH was entered as dependent variable (R = 0.730; P = .0001), only serum albumin (β = 0.495) and age (β = -0.280), but not dietary intake or NGAL, contributed to the model.

CONCLUSIONS

In MHD, markers of thiol oxidation including CySSP and PTI show independent association with dietary intake and NGAL, whereas PSH, a marker of thiol-reducing capacity, did not associate with these same variables. The mechanism(s) responsible for inverse association between oxidative stress and food intake in MHD remain undefined.

Relationship between uremic toxins and oxidative stress in patients with chronic renal failure

OBJECTIVE

Uremic toxins play a critical role in the manifestation of the uremic syndrome. This is a consequence of retention of such substances in chronic renal failure patients and interactions between them. To date >100 uremic compounds have been discovered. The aim of this study was to elucidate potential relationships between N-methyl-2-pyridone-5-carboxamide (Me2PY) and N-methyl-4-pyridone-5-carboxamide (Me4PY), two uremic compounds, and different parameters of oxidative stress.

MATERIAL AND METHODS

Forty-three non-dialyzed patients at the Nephrological Outpatients Clinic of Gdansk were enrolled and divided into two groups: (i) 20 patients with a mean estimated glomerular filtration rate (eGFR) of 22.7 ml/min/1.73 m(2); and (ii) 23 patients with a mean eGFR of 12.4 ml/min/1.73 m(2). In both groups, the plasma concentrations of uremic toxins (Me2PY, Me4PY, creatinine), malonyldialdehyde (MDA) and carbonyl groups and the erythrocyte concentration of glutathione (GSH) were analyzed. Correlations between uremic toxins and oxidative stress markers were calculated using Pearson's correlation.

RESULTS

We observed significant correlations between serum creatinine and Me2PY (r=0.68; p=0.00001), eGFR and Me2PY (r=-0.55; p=0.00001), Me4PY and serum creatinine (r=0.64, p=0.00001), Me4PY and eGFR (r=-0.59; p=0.00008), MDA and Me2PY (r=0.42; p=0.006), MDA and Me4PY (r=0.38; p=0.02), GSH and Me2PY (r=-0.37; p=0.02) and GSH and Me4PY (r=-0.46; p=0.005), and in particular in patients with severe renal impairment.

CONCLUSIONS

We conclude that there is a relationship between the novel uremic toxins described and oxidative stress markers. However, elucidation of the exact pathogenetic links requires further detailed studies.

Propionyl-L-Carnitine Therapy: Effects on Endothelin-1 and Homocysteine Levels in Patients with Peripheral Arterial Disease and End-Stage Renal Disease

BACKGROUND/AIMS

Recent data have addressed the issue of higher levels of homocysteine (Hcy) and endothelin-1 (ET-1) in end-stage renal disease (ESRD) that may be considered an independent predictor for cardiovascular disease. The prevalence of peripheral arterial disease (PAD) in patients with ESRD has been reported to be relevant, highlighting its clinical importance. We aimed to explore the therapeutic role of propionyl-L-carnitine (PLC) in hemodialysis patients with PAD by measuring ankle/brachial index (ABI), ET-1 and Hcy.

DESIGN

Randomized, double-blind, placebo-controlled trial.

METHODS

Sixty-four patients on hemodialysis with chronic renal insufficiency and PAD were assigned to receive either intravenous PLC (600 mg) or placebo 3 times weekly for 12 months. The ABI and plasma levels of ET-1 and Hcy were measured at baseline, 6 and 12 months.

RESULTS

In the PLC-treated group, progressive increases in ABI were observed, while in the placebo group the reverse trend was seen. Highly significant and progressive reductions in plasma levels of ET-1 and Hcy, compared to baseline, were also seen in the PLC-treated group.

CONCLUSIONS

Hemodynamic flow, endothelial profile and Hcy levels were ameliorated by the administration of PLC in hemodialysis patients with ESRD and PAD.

A Randomised, Controlled Clinical Trial Evaluating Changes in Therapeutic Efficacy and Oxidative Parameters after Treatment with Propionyl L-Carnitine in Patients with Peripheral Arterial Disease Requiring Haemodialysis

OBJECTIVE

We explored the efficacy of intravenous therapy with propionyl L-carnitine in patients with both peripheral arterial disease (PAD) and chronic renal insufficiency requiring haemodialysis.

METHODS

The trial was a randomised, double-blind, placebo-controlled trial. Sixty-four patients on haemodialysis (32 per treatment arm) with chronic renal insufficiency and PAD were assigned to receive either intravenous propionyl L-carnitine 600 mg or placebo 3 times weekly for 12 months. The main outcome measures were the ankle/brachial index (ABI), plasma malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) concentrations, and the plasma nitrite/nitrate ratio (NO(2)/NO(3)); these were measured at baseline and at 6 and 12 months.

RESULTS

Significant increases in ABI were observed in the propionyl L-carnitine group, whereas in the placebo group the reverse trend was seen. In patients treated with propionyl L-carnitine, significant progressive decreases were seen in plasma MDA, 4-HNE and the NO(2)/NO(3) ratio from baseline. In the placebo-treated group, only weakly significant or no differences were seen.

CONCLUSION

Intravenous administration of propionyl L-carnitine to haemodialysis patients with PAD improves both haemodynamic flow and the oxidative profile.