Brain natriuretic peptide between traditional and nontraditional risk factors in hemodialysis patients: analysis of cardiovascular mortality in a two-year follow-up

The association between dose of hemodialysis and patients mortality in a prospective cohort study

Dialysis adequacy is a known risk factor for mortality in maintenance hemodialysis (MHD) patients. However, the optimal dialysis dose remains controversial. Therefore, we aimed to explore the relationship between dialysis dose and all-cause and cardiovascular disease (CVD) mortality among MHD. We examined the associations of dialysis dose with mortality in a cohort (n = 558) of MHD patients from 31 December 2015 to 31 December 2020. Dialysis adequacy was assessed using baseline Single-pool Kt/V_urea (spKt/V), which was categorized into three groups, and the lowest dose group was used as the reference category. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression models. A total of 214 patients died (64.5% for CVD). Compared with the low-dose group, high-dose group could reduce the risk of all-cause mortality by 33% (HR = 0.67, 95% CI: 0.47–0.98). Of note, when stratification by age, high-dose group was associated with both lower all-cause (HR = 0.46, 95% CI: 0.26–0.81) and CVD mortality (HR = 0.42, 95% CI: 0.20–0.88) among patients with age below 65 years. When stratification by dialysis age, high-dose group was associated with decreased risk of CVD mortality (HR = 0.43, 95% CI: 0.20–0.91) among patients with dialysis age over 60 months. spKt/V is a simple index of hemodialysis dose used in clinical practice and a useful modifiable factor in predicting the risk of death, especially in MHD patients under 65 years old or dialysis age more than 60 months.

Pathophysiology and significance of natriuretic peptides in patients with end-stage kidney disease

Natriuretic peptides (NP), especially B type (BNP) and its N-terminal pro-B type natriuretic peptide (NT-proBNP), have long been regarded as biomarkers of volume overload and tools to exclude heart failure in the general population. However, their role in end-stage kidney disease (ESKD) is less certain given that BNP and NT-proBNP are excreted by the kidney and so serum concentrations of NPs are nearly universally elevated compared to controls. Nevertheless, the accumulated evidence suggests thatserum concentrations of NPs in patients with ESKD show moderate or strong positive relationships with underlying heart disease, abnormal cardiac structure or function and mortality. Limited evidence also supports the role of BNP including NT-proBNP, ANP in some studies, rather than CNP or DNP in risk stratification among ESKD patients as well as the utility of BNP samplings pre- and post- hemodialysis. However, studies of the cut-off values of NPs have yielded inconsistent results, such that further large-scale studies are needed to clarify these issues. This review summarizes the pathophysiology and significance of NPs in ESKD patients, especially their potential role as risk stratification biomarkers in clinical management.

Association between autonomic nervous dysfunction and cellular inflammation in end-stage renal disease

Background

Alterations in autonomic nervous function are common in hemodialysis (HD) patients. Sympathetic as well as parasympathetic activation may be associated with immune and inflammatory responses. We intended to confirm a role of autonomous dysregulation for inflammation in HD patients.

Methods

30 HD patients (including 15 diabetics) and 15 healthy controls were studied for heart rate variability (HRV) using 5 min ECG recordings. Heart rate variability was estimated by time-domain parameters (the standard deviation of the RR intervals (SDNN) and the percentage of pairs of adjacent RR intervals differing by >50 ms (pNN50)) and frequency-domain-analysis (high- and low-frequency variation of RR intervals, HF and LF). Inflammation was detected as serum C-reactive Protein (CRP), IL-6 and circulating monocyte subpopulation numbers. Immune cells were characterized by ACh receptor expression.

Results

Patients differed from controls in terms of age (68.0 [14.8] yrs vs. 58.0 [13.0] yrs, p < 0.001; Median [IQR]) and sex. However, HRV parameters were different in controls and HD patients (SDNN controls 34.0 [14.0] ms, HD patients 15.5 [14.8] ms, p < 0.01). This finding was not restricted to patients with diabetes mellitus (diab), although diabetes is an important cause of autonomous dysfunction (SDNN, diab 13.0 [14.0] ms, non-diab 18.0 [15.3] ms, p = 0.8). LF and HF were reduced by the same magnitude to 1/3 of those in controls. Patients suffered from chronic inflammation (CRP 9.4 [12.9] mg/l, controls 1.6 [2.4] mg/l, p < 0.001) and expanded proinflammatory monocyte subpopulations (CD14++/CD16+ cells: patients 41 [27]/μl, controls 24 [18]/μl, p < 0.01). ECG parameters did not correlate with inflammation in patients, but monocyte ACh receptor expression was enhanced, indicating potentially elevated responsiveness of this cell type to parasympathetic regulation.

Conclusions

HD patients have strongly impaired HRV. Chronic inflammation is not related to autonomous dysfunction, although monocytes express the ACh receptor at enhanced density making them potentially more sensitive to parasympathetic effects.

Trial registration

This study was listed with ClinicalTrials.gov (NCT00878033).

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-016-0385-1) contains supplementary material, which is available to authorized users.

B-type natriuretic peptide and prognosis of end-stage renal disease: a meta-analysis

Background

The prognostic importance of B-type natriuretic peptide (BNP) or N-terminal pro BNP (NT-proBNP) in patients with end-stage renal disease (ESRD) remains controversial.

Methodology/Principal Findings

We conducted an unrestricted search from the MEDLINE and EMBASE in all languages that were published between 1966 and Augest2013. Twenty-seven long-term prospective studies met our inclusion criterias. From the pooled analysis, elevated BNP/NT-proBNP was significantly associated with increased all cause mortality [odds ratio (OR), 3.85; 95% CI, 3.11 to 4.75], cardiovascular mortality (OR, 4.05; 95% CI, 2.53 to 6.84), and cardiovascular events (OR, 7.02; 95% CI, 2.21 to 22.33). The funnel plot showed no evidence of publication bias. The corresponding pooled positive and negative likelihood ratio for prediction of all cause mortality were 1.86 (95% CI, 1.66 to 2.08) and 0.48 (95% CI, 0.42 to 0.55), respectively.

Conclusions/Significance

BNP/NT-proBNP is a promising prognostic tool to risk-stratify the patients with ESRD. Further investigations are warranted to elucidate the specific pathogenic mechanisms and the impact of other potential prognostic factors.