Novel biomarkers do not correlate with severity of vascular stiffness in CKD patients with severe co-morbid disease

BACKGROUND/AIMS

Novel biomarkers may help explain the pathobiology of vascular disease in chronic kidney disease, and thus set the stage for identification of therapeutic targets, potential reversibility, and improved outcomes in this population.

METHODS

124 subjects with GFR <60 ml/min or on renal replacement therapy underwent measurement of inflammatory, vascular and cardiac biomarkers as well as aortic pulse wave velocity (PWV) testing. A subset of patients (n = 60) had repeat PWV measured at 6 months.

RESULTS

Thirty-four percent of the patients were diabetic, and 50% had a history of cardiovascular disease or congestive heart failure. Median PWV was 9.8 (IQR 8.3-12.7) m/s. No significant correlations between the measured biomarkers and baseline PWV was observed. An increase in PWV (>1.5 m/s) over 6 months was observed in those subjects with diabetes, a higher brain natriuretic peptide level, lower cholesterol and lower phosphate level. Age (HR 1.086, p = 0.0028), fetuin (0.024, p = 0.0448), and interleukin-10 (top tertile HR 4.720, p = 0.0359) were associated with mortality.

CONCLUSIONS

In this cohort of patients with chronic kidney disease and diabetes and/or heart disease, we were unable to demonstrate that select biomarkers can inform processes leading to vascular disease. Biomarkers do appear to have utility in predicting future events in this population.

Is N-terminal probrain-type natriuretic peptide a clinically useful biomarker of volume overload in peritoneal dialysis patients?

BACKGROUND

Brain natriuretic peptide (BNP) has been reported to be a powerful predictor of peritoneal dialysis patient survival. However, it is unclear as to whether this is related to cardiac dysfunction or chronic volume overload.

METHODS

To investigate the relationship between BNP, cardiac function and fluid volume overload, we reviewed multifrequency bioimpedance, transthoracic echocardiography and serum N-terminal probrain-type natriuretic peptide (NTproBNP) in 115 stable peritoneal dialysis outpatients attending for assessment of peritoneal dialysis and transport status.

RESULTS

In this cross-sectional study, the median NTproBNP was 251 (118-605) pmol/L. On simple univariate analysis, NTproBNP was associated with markers of residual renal function, volume overload, hypertension and hypertensive cardiac disease and inflammation [reduced serum albumin and raised C-reactive protein]. However, on multivariate logistical regression analysis, the strongest association for log NTproBNP was with the estimated right ventricular end-systolic pressure (β = 0.02, F = 11.5, P = 0.001), followed by log 24-h urine volume (β = -0.19, F = 10.7, P = 0.002), extracellular/total body water ratio (β = 13.5, F = 6.1, P = 0.017) and the number of different antihypertensive medications prescribed (β = 0.15, F = 8.7, P = 0.005).

CONCLUSION

In this cross-sectional study, although NTproBNP was associated with residual renal function, cardiac hypertrophy, volume overload and inflammation on simple univariate analysis, on further examination NTproBNP was predominantly affected by factors associated with volume overload, and these results require confirmation in a prospective study.

Sudden cardiac death in patients with chronic kidney disease: prevention is the sine qua non

Despite developments in the technology of dialysis procedures and improvements in the understanding of systemic derangements related to chronic kidney disease (CKD), cardiovascular disease is the major cause of death. Unfortunately, the leading subset of cardiovascular disease death is sudden cardiac death (SCD). To date much effort has been exerted to figure out the clues pointing to the risk of future development of SCD in patients with CKD. However, none of these factors satisfactorily detects a truly vulnerable dialysis patient. Thus, recently, it has been advocated that a combination of noninvasive risk assessment methods, carefully chosen to reflect the different aspects of the underlying pathology and changes in the myocardial substrate in CKD, could help to identify patients at high risk of SCD within the CKD. In this review, we aimed to summarize what is known about risk stratification of patients with CKD and appropriate prevention strategies with a special emphasis on recent developments and the use of complimentary tests perhaps as a risk prediction rule.

Comparison of B-type natriuretic peptide and NT proBNP as predictors of survival in patients on high-flux hemodialysis and hemodiafiltration

End stage renal failure is associated with very high risk of cardiovascular disease. Serum levels of B-type natriuretic peptide (BNP) and NT proBNP reflect cardiovascular risk but it is unknown which of these peptides is a better predictor of survival in this population. BNP and NT proBNP levels and other relevant parameters were measured in 103 patients on high-flux hemodialysis (HD) and hemodiafiltration. Patients were followed for 4 years or until transplantation or death. Median BNP level was 262 pg/mL while the corresponding NT proBNP level was 362 pg/mL. Levels of these peptides were significantly lower in patients receiving hemodiafiltration than in those on high-flux HD. Only 1 of the 26 patients with normal NT proBNP died during follow-up while 3 of the 33 patients with normal BNP levels died in the same period. Both median BNP and NT proBNP levels were higher in those who died during follow-up than in those who survived 4 years. Cox Proportional Hazard models showed that both logBNP and log NT proBNP were independent predictors of survival. The area under the receiver operating characteristic curve was very similar for BNP and NT proBNP (0.779 vs. 0.781) for predicting 4-year survival. Net reclassification improvement analysis showed that adding NT proBNP to the baseline model lead to improved prediction of 4-year survival. BNP and NT proBNP levels were markedly elevated in HD patients and were highly predictive of survival. NT proBNP may have marginal advantage over BNP in predicting survival in this population.

Left atrial volume is an independent predictor of mortality in CAPD patients

BACKGROUND

Echocardiography is an established technique to estimate the risk for cardiovascular complications in patients with end-stage renal disease (ESRD). An enlarged left atrium (LA) has recently emerged as a marker of adverse cardiovascular outcomes in various pathologic conditions. However, there have been few studies to evaluate its prognostic value in patients with ESRD, particularly those receiving continuous ambulatory peritoneal dialysis (CAPD).

METHODS

We conducted an observational cohort study to investigate whether enlarged LA can predict patient outcome in 216 patients with CAPD. Study outcomes were all-cause and cardiovascular mortality.

RESULTS

Increased left atrium volume index (LAVI > 32 mL/m(2)) was observed in 99 (45.8%) of the CAPD patients. During the follow-up (26.3 ± 18.6 months), 20 patients (9.3%) died. Kaplan-Meier analysis revealed that the 5-year survival rate was significantly lower in patients with LAVI > 32 mL/m(2) than those with LAVI ≤ 32 mL/m(2) (69 versus 82%, P = 0.024). In multivariate analyses adjusted for echocardiographic parameters and clinical and laboratory data, increased LAVI was an independent predictor of all-cause mortality [hazard ratio (HR) 1.05, 95% confidence interval (CI) 1.01-1.10, P = 0.03] and cardiovascular mortality (HR 1.08, 95% CI 1.02-1.14, P = 0.006). Furthermore, increased LAVI provided the highest predictive value for all-cause mortality [area under the receiver operating characteristic curve (AUC) = 0.766, P < 0.001] and cardiovascular mortality (AUC = 0.836, P < 0.001) among the measured echocardiographic parameters.

CONCLUSIONS

We showed that increased LAVI predicted adverse outcomes better than other echocardiographic parameters in patients with CAPD.

Fluid status in peritoneal dialysis patients: the European Body Composition Monitoring (EuroBCM) study cohort

BACKGROUND

Euvolemia is an important adequacy parameter in peritoneal dialysis (PD) patients. However, accurate tools to evaluate volume status in clinical practice and data on volume status in PD patients as compared to healthy population, and the associated factors, have not been available so far.

METHODS

We used a bio-impedance spectroscopy device, the Body Composition Monitor (BCM) to assess volume status in a cross-sectional cohort of prevalent PD patients in different European countries. The results were compared to an age and gender matched healthy population.

RESULTS

Only 40% out of 639 patients from 28 centres in 6 countries were normovolemic. Severe fluid overload was present in 25.2%. There was a wide scatter in the relation between blood pressure and volume status. In a multivariate analysis in the subgroup of patients from countries with unrestricted availability of all PD modalities and fluid types, older age, male gender, lower serum albumin, lower BMI, diabetes, higher systolic blood pressure, and use of at least one exchange per day with the highest hypertonic glucose were associated with higher relative tissue hydration. Neither urinary output nor ultrafiltration, PD fluid type or PD modality were retained in the model (total R² of the model = 0.57).

CONCLUSIONS

The EuroBCM study demonstrates some interesting issues regarding volume status in PD. As in HD patients, hypervolemia is a frequent condition in PD patients and blood pressure can be a misleading clinical tool to evaluate volume status. To monitor fluid balance, not only fluid output but also dietary input should be considered. Close monitoring of volume status, a correct dialysis prescription adapted to the needs of the patient and dietary measures seem to be warranted to avoid hypervolemia.

N-terminal proBNP--marker of cardiac dysfunction, fluid overload, or malnutrition in hemodialysis patients?

BACKGROUND AND OBJECTIVES

N-terminal probrain type natriuretic peptide (NTproBNP) has been proven to be a valuable biomarker for predicting cardiac events and mortality in the hemodialysis population. However recent reports have suggested that NTproBNP is a marker of volume overload rather than one of cardiac dysfunction. Therefore this study investigated the effect of fluid volume status on NTproBNP.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Volume status was determined pre- and postdialysis in 72 stable hemodialysis outpatients by multifrequency bioimpedance, and the relationship to NTproBNP values was examined.

RESULTS

The mean and median NTproBNP values were 931.9 +/- 230 and 242 (90 to 688) pmol/L, respectively. On simple correlation, NTproBNP was associated with markers of volume overload and cardiac dysfunction. However, on logistical regression analysis, the strongest association was with the predialysis ratio of extracellular water/total body water (beta 26.6, F29.6, P = 0.000), followed by postdialysis mean arterial blood pressure (beta 0.14, F17.1, P = 0.000), dialysate calcium concentration (beta -1.19, F14.1, P = 0.002), and change in extracellular fluid volume with dialysis (beta 0.27, F7.4, P = 0.009)

CONCLUSIONS

In this study, NTproBNP was not associated with cardiac dysfunction as assessed by transthoracic echo or nuclear medicine scintigraphy but was dependent on factors associated with volume overload. However, because bioimpedance results can also be affected by malnutrition with loss of cell mass, NTproBNP may be elevated not only in patients with volume overload, but also those with malnutrition.

The effect of lipoproteins on the development and progression of renal disease

The field of research examining how lipoproteins may contribute to the development and/or progression of renal disease has rapidly expanded over the last 25 years. In animal models, lipoproteins and lipids have been associated with both the initiation and progression of renal disease. Numerous potential mechanisms of lipoprotein-induced renal injury have been identified by utilizing animal models and tissue-culture experiments. However, with the exception of rare genetic mutations, the association between lipoproteins and human renal disease is less clear. In humans, the evidence that lipid-lowering therapy delays renal progression is limited. The purpose of this paper is to review the current literature on lipoprotein abnormalities and the development or progression of renal disease.