Subclinical cardiovascular disease markers and vitamin D deficiency in non-dialysis chronic kidney disease patients

Insulin Resistance and Vitamin D Deficiency: A Link Beyond the Appearances

Vitamin D is a steroid hormone that plays a key role in the regulation of body homeostasis, including cardiovascular function. Although the chronic deficiency of vitamin D is associated with cardiovascular risk factors, as well as with an adverse prognosis, randomized controlled trials have failed in demonstrating that dietary vitamin D supplementation could ameliorate the prognosis of patients with cardiovascular diseases, and suggested that vitamin D deficiency is the expression of the effects of other determinants of cardiovascular risk. Thus, the supplementation of vitamin D is not sufficient to improve the cardiovascular risk profile and prognosis. Insulin resistance is a complex phenomenon that plays a key role in the pathogenesis of conventional cardiovascular risk factors. Interestingly, defects of vitamin D and insulin resistance have a superimposable epidemiological distribution. According to the common view, Insulin resistance is considered the direct or indirect consequence of vitamin D deficiency. However, it is also reasonable to speculate that the deficit or the impaired action of vitamin D, in some circumstances, could be the result of the same pathogenic mechanisms responsible of insulin resistance development. In this case, vitamin D deficiency could be considered an epiphenomenon of insulin resistance. Insulin resistance is a reversible condition, being possibly ameliorated by physical activity and hypocaloric diets. Notably, both physical exercise and energy-restricted dietary regimens are associated with an increase of vitamin D levels. These findings indicate that improving insulin resistance condition is a necessary step to ameliorate vitamin D supplementation-based strategies in cardiovascular prevention.

Effect of Vitamin D Supplementation on the Regulation of Blood Pressure in Iranian Patients with Essential Hypertension: A Clinical Trial

BACKGROUND

Low serum vitamin D level is associated with both high blood pressure and incidence of primary hypertension. Experimental studies suggest that vitamin D supplements may reduce blood pressure.

OBJECTIVE

The aim of this study was to investigate whether vitamin D supplementation reduces systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) in Iranian patients with essential hypertension.

METHOD

A total of 173 patients with essential hypertension participated in this open-label clinical trial. SBP, DBP, and serum vitamin D levels were measured at baseline and at the end of the study. Vitamin D was administered at a dose of 50,000 IU/week, and 1000 IU/day in patients with serum vitamin D levels <20 ng/mL and 20-30 ng/mL, respectively, for 8 weeks.

RESULTS

Based on serum vitamin D levels, 45.1%, 17.3%, and 29.5% of patients were deficient, insufficient, and sufficient for vitamin D intake, respectively. Baseline serum levels of vitamin D were not correlated with SBP, DBP, and MAP at the beginning of the study (p = ns). Multiple logistic regression analysis revealed that the risk of vitamin D deficiency was 2.5-fold times higher in women than in men (p = 0.03). After 8 weeks of supplementation with vitamin D, mean SBP and MAP were significantly reduced by 5.5 ± 16.16 (p = 0.01) and 3.7 ± 9.24 (p = 0.004) mmHg, respectively. Neither sex nor age could significantly predict BP response to vitamin D supplementation.

CONCLUSION

Vitamin D supplementation may significantly reduce SBP and MAP but not DBP in patients with essential hypertension.

Impact of Physical Activity and Natural Bioactive Compounds on Endothelial Dysfunction in Chronic Kidney Disease

Chronic kidney disease (CKD) represents a world-wide public health problem. Inflammation, endothelial dysfunction (ED) and vascular calcifications are clinical features of CKD patients that increase cardiovascular (CV) mortality. CKD-related CV disease pathogenic mechanisms are not only associated with traditional factors such as arterial hypertension and dyslipidemia, but also with ED, oxidative stress and low-grade inflammation. The typical comorbidities of CKD contribute to reduce the performance and the levels of the physical activity in nephropathic patients compared to healthy subjects. Currently, the effective role of physical activity on ED is still debated, but the available few literature data suggest its positive contribution. Another possible adjuvant treatment of ED in CKD patients is represented by natural bioactive compounds (NBCs). Among these, minor polar compounds of extra virgin olive oil (hydroxytyrosol, tyrosol and oleocanthal), polyphenols, and vitamin D seem to exert a beneficial role on ED in CKD patients. The objective of the review is to evaluate the effectiveness of physical exercise protocols and/or NBCs on ED in CKD patients.

Are Nutraceuticals Beneficial in Chronic Kidney Disease?

Chronic kidney disease (CKD) is a worldwide health problem in which prevalence is constantly rising. The pathophysiology of CKD is complicated and has not been fully resolved. However, elevated oxidative stress is considered to play a vital role in the development of this disease. CKD is also thought to be an inflammatory disorder in which uremic toxins participate in the development of the inflammatory milieu. A healthy, balanced diet supports the maintenance of a good health status as it helps to reduce the risk of the development of chronic diseases, including chronic kidney disease, diabetes mellitus, and hypertension. Numerous studies have demonstrated that functional molecules and nutrients, including fatty acids and fiber as well as nutraceuticals such as curcumin, steviol glycosides, and resveratrol not only exert beneficial effects on pro-inflammatory and anti-inflammatory pathways but also on gut mucosa. Nutraceuticals have attracted great interest recently due to their potential favorable physiological effects on the human body and their safety. This review presents some nutraceuticals in which consumption could exert a beneficial impact on the development and progression of renal disease as well cardiovascular disease.

Pregnancy-associated plasma protein A as a predictor of all-cause mortality and cardiovascular events in patients with chronic kidney disease: a meta-analysis of prospective studies

INTRODUCTION

The aim of the study was to assess the association of elevated serum pregnancy associated plasma protein A (PAPP-A) and the risk of all-cause mortality, cardiovascular events and mortality due to infection in patients with chronic kidney disease (CKD).

MATERIAL AND METHODS

We systematically searched the Medline database up to March 2017. A random effects model was used to pool the relative risks (RRs) and their 95% confidence intervals (CIs). Sensitivity analysis and subgroup analysis were performed to explore the potential sources of heterogeneity.

RESULTS

Six studies involving 2034 subjects were included. The pooled RRs for the risk of all-cause mortality and cardiovascular events were 1.50 (95% CI: 1.17-1.92), 1.26 (95% CI: 0.95-1.69), respectively. Sensitivity analysis by excluding each individual study showed no influence on the main results. Subgroup analysis showed that age, male proportion, follow-up term, and assay methods were not modifiable factors.

CONCLUSIONS

Our study suggests that elevated serum PAPP-A is associated with the risk of all-cause mortality in patients with CKD.

Associations between neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, albuminuria and uric acid and the estimated glomerular filtration rate in hypertensive patients with chronic kidney disease stages 1-3

INTRODUCTION

The neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), albuminuria and uric acid are known to be independent predictors of hypertension and cardiovascular mortality. However, to date, no study has been conducted describing the relationships between the NLR, PLR and estimated glomerular filtration rate (eGFR) in hypertensive patients with chronic kidney disease (CKD) who do not require renal replacement therapy.

MATERIAL AND METHODS

This prospective study included 271 patients with essential hypertension and eGFR ≥ 30 ml/min/1.73 m². The patients were divided into two groups: those with CKD stages 1 and 2 and those with stage 3. We used the complete blood count to calculate the NLR and PLR, and we measured the albuminuria and uric acid levels. Then, we studied their associations with the eGFR and their potential uses as independent risk factors for renal damage.

RESULTS

The NLR, albuminuria and uric acid were higher in patients with CKD stage 3 than in those with stages 1 and 2 (p = 0.013, p = 0.001 and p = 0.001, respectively). However, no significant difference was detected in the PLR. In stage 3 patients, albuminuria and uric acid were found to be independent risk factors affecting the eGFR (p = 0.042 and p = 0.001, respectively). However, the effects of the NLR and PLR on the eGFR were not significant (p = 0.104 and p = 0.578, respectively).

CONCLUSIONS

The NLR, similar to albuminuria and uric acid, the NLR was found to be a specific marker for CKD stage 3 patients. However, the NLR and PLR did not act as independent risk factors affecting the eGFR.

Bacterial infections are associated with cardiovascular disease in Iran: a meta-analysis

INTRODUCTION

The present study aimed to assess the prevalence and association of various bacterial infections with cardiovascular disease (CVD) in Iran.

MATERIAL AND METHODS

An electronic search was performed using related keywords in the national and international databases up to June 30, 2017. Out of the 1807 articles found on the associations between bacterial infections and CVD, 20 relevant studies were selected for the meta-analysis.

RESULTS

The prevalence of bacterial infections was higher in case groups compared with the control groups. Odds ratios for assessing the association between Chlamydia pneumonia infection and CVD based on PCR, IgG and IgA tests were 7.420 (95% CI: 3.088-17.827), 3.710 (95% CI: 1.361-10.115) and 2.492 (95% CI: 1.305-4.756), respectively. Moreover, the calculated odds ratio for Mycoplasma pneumonia infection was 1.815 (95% CI: 0.973-3.386). For Helicobacter pylori infection, odds ratios based on IgG and IgA tests were 3.160 (95% CI: 1.957-5.102) and 0.643 (95% CI: 0.414-0.999), respectively.

CONCLUSIONS

The present meta-analysis suggested that there was a significant association between H. pylori, C. pneumonia and M. pneumonia infections and CVD in Iran. These findings confirm the potential role of bacterial infections as predisposing factors for CVD.

Is N-terminal pro-brain natriuretic peptide a reliable marker for body fluid status in children with chronic kidney disease?

INTRODUCTION

Brain natriuretic peptides, released in response to left ventricular stress, have a strong prognostic value in dialysis patients. However, their role in detecting abnormalities of fluid status is under debate; the relationship between volume status and brain natriuretic peptides (BNPs) differs among various studies. The aim of our study was to evaluate the clinical utility of N-terminal proBNP in the assessment of fluid status and cardiovascular risk in this setting.

MATERIAL AND METHODS

The study included 65 children: 10 pre-dialysis, 13 hemodialysis, 12 peritoneal dialysis patients and 30 healthy controls. Volume status was determined by multifrequency bioimpedance and NT-pro-BNP, as well as echocardiography to estimate the left ventricle structure and function.

RESULTS

The median log NT-proBNP values of hemodialysis and peritoneal dialysis patients were 3.66 (2.05-4.90) and 3.57 (2.51-4.13) pg/ml, respectively, and significantly higher compared with the control group (p < 0.001, p < 0.001). On simple correlation, NT-proBNP was correlated with markers of volume overload and cardiac dysfunction. On multivariate regression analysis, only left ventricle mass index (β = 0.402, p = 0.003) and left atrium diameter (β = 0.263, p = 0.018) were independently associated with NT-proBNP (adjusted R 2 of the model: 0.707, p < 0.001).

CONCLUSIONS

Our research suggested that NT-proBNP, which was correlated with LV systolic and diastolic dysfunction and fluid overload as assessed by bioimpedance, can be used to evaluate cardiovascular states in a chronic kidney disease (CKD) population. From the early stages of CKD, periodic monitoring of NT-proBNP levels may be essential for early detection of patients with high risk of cardiovascular events, and for taking preventive intervention as soon as possible.

Clinical Usefulness of the Cardio-Ankle Vascular Index as a Predictor of Primary Cardiovascular Events in Patients With Chronic Kidney Disease

Background

The cardio-ankle vascular index (CAVI) is a physiologic marker reflecting arterial function. There have been no prospective studies investigating the relationship between CAVI and cardiovascular events in patients with chronic kidney disease (CKD). The aim of this prospective study was to assess the clinical usefulness of CAVI as a predictor of primary cardiovascular events in patients with CKD.

Methods

The study enrolled 460 outpatients with CKD but no history of cardiovascular disease (152 men and 308 women; mean ± standard deviation age, 74 ± 12 years). Patients were assigned to one of three groups: low (L, CAVI < 9; n = 100), medium (M, CAVI 9 - 10; n = 199), or high (H, CAVI > 10; n = 161). The utility of the CAVI as a predictor of primary cardiovascular events was evaluated.

Results

During the follow-up period (median 60.1 months), major adverse cardiovascular events (MACE) occurred in 91 cases (L, 8 (8.0%); M, 31 (15.6%); H, 52 (32.3%); P < 0.001, log-rank test). On multivariate Cox regression analysis, the risk for a MACE was significantly higher in group H than in non-group H (hazard ratio, 2.04; 95% confidence interval, 1.31 - 3.02; P < 0.01). A CAVI cut-off of 9.7 yielded the largest area under the curve, 0.701 (95% confidence interval: 0.657 - 0.743, P < 0.001), indicating a sensitivity of 74.0% and a specificity of 59.6% for discriminating between those who did and did not experience a MACE during follow-up.

Conclusions

The results of this study showed that a high CAVI is a predictor of primary cardiovascular events in patients with CKD.

Native vitamin D in pre-dialysis chronic kidney disease

Chronic kidney disease patients have a high prevalence of vitamin D insufficiency/deficiency. Vitamin D deficiency has been associated with a variety of bone, metabolic and cardiovascular disorders. However, the role of native vitamin D supplementation (ergocalciferol, cholecalciferol or calcifediol) remains unclear in chronic kidney disease (CKD), particularly in the pre-dialytic phase. Several international guidelines have been developed on CKD-Mineral and Bone Disorder, but the optimal strategy for native vitamin D supplementation and its clinical benefit remains a subject of debate in the scientific community. This paper aims to review the available literature, including randomized clinical trials that evaluated the effects of native vitamin D supplementation on pre-dialysis CKD on biochemical and clinically relevant outcomes.

Influence of renal function on the association between homocysteine level and risk of ischemic stroke

We examined whether the association between total homocysteine (tHCY) and risk of ischemic stroke (IS) varies depending on renal function to gain insight into why tHCY-lowering vitamins do not reduce the incidence of cardiovascular disease in clinical trials. We analyzed data from 542 IS patients with large artery atherosclerosis (LAA) or small artery occlusion (SAO) after stratification by estimated glomerular filtration rate (eGFR) to evaluate renal function. We found that tHCY level was positively associated with the occurrence of IS in both LAA (OR: 1.159, 95% CI: 1.074-1.252, P<0.001) and SAO (OR: 1.143, 95% CI: 1.064-1.228, P<0.001) patients and in LAA (OR: 1.135, 95% CI: 1.047-1.230, P=0.002) and SAO (OR: 1.159, 95% CI: 1.060-1.268, P=0.001) subgroups with normal renal function but not in LAA or SAO subgroups with renal insufficiency. eGFR level was positively associated with IS in LAA (OR: 1.022, 95% CI: 1.010-1.034, P<0.001) and SAO (OR: 1.024, 1.012-1.037, P<0.001) subgroups with normal renal function but was negatively associated with IS in LAA (OR: 0.875, 95% CI: 0.829-0.925, P<0.001) and SAO (OR: 0.890, 95% CI: 0.850-0.932, P<0.001) subgroups with renal insufficiency. Folic acid level was negatively associated with IS in LAA (OR: 0.734, 95% CI: 0.606-0.889, P=0.002) and SAO (OR: 0.861, 95% CI: 0.767-0.967, P=0.012) subgroups with renal insufficiency. Therefore, renal function as evaluated by eGFR exerts a significant influence on the association between tHCY and risk of IS.