N-terminal pro brain natriuretic peptide predicts mortality in patients with end-stage renal disease in hemodialysis

Nt-proBNP in haemodialysis patients: a preliminary study

OBJECTIVE

N-terminal pro-brain natriuretic peptide (Nt-proBNP) is a marker of left ventricular function. Although many factors can increase left ventricular dysfunction in haemodialysis patients, the role of Nt-proBNP is uncertain.

MATERIAL AND METHODS

Serum concentrations of Nt-proBNP and troponin T were measured by electrochemiluminescence and C-reactive protein by immunoturbidimetry in 52 dialysis patients followed-up for 36 months.

RESULTS

Nt-proBNP correlated (p<0.05) with time on haemodialysis (rho=0.345), left ventricular mass index (r=0.596), troponin T level (r=0.605) and age (r=0.296). Patients with a history of heart disease showed higher levels of Nt-proBNP (median; minimum-maximum ngl/L) (15,571; 1,553-209,451) than those without (4,535; 751-115,078) (p<0.01). Sensitivity and specificity of Nt-proBNP in the detection of left ventricular dysfunction (ventricular ejection fraction < 45%) were 1.0 and 0.782, respectively. In the univariate analysis, patients with Nt-proBNP levels > or = 33,314 ng/L, CRP > or = 5 mg/L or troponin T > or = 0.1 microg/L had poorer probabilities of 1-year, 2-year and 3-year survival than patients with lower levels. Unfavourable prognostic factors in the multivariate analysis were CRP > 5 mg/L and Tn T > 0.1 microg/L.

CONCLUSIONS

Nt-proBNP showed good diagnostic performance for detecting left ventricular dysfunction and was an important predictor of mortality in haemodialysis patients in the univariate analysis. In the multivariate analysis, Nt-proBNP lost its prognostic value, whereas for CRP and Tn T it was maintained.

Natriuretic peptides in chronic kidney disease and during renal replacement therapy: an update

Natriuretic peptides play a major role in sodium and body volume homeostasis in patients with adequate kidney function. Circulating B-type natriuretic peptide (BNP) and its amino-terminal fragment NT-proBNP provide important information on cardiac dysfunction, hypervolemia, and risk for hospitalization or death even in patients with severe impairment of kidney function. NT-proBNP acts also as significant independent predictor of progression of chronic kidney disease (CKD). Differences in elimination and degradation as well as molecular weight and half-life between BNP and NT-proBNP are responsible for different plasma levels, different membrane-dependent removal during hemodialysis, and different diagnostic and prognostic power to predict morbidity and mortality in patients at different stages of CKD and in those on hemodialysis or peritoneal dialysis. Serial estimations of natriuretic peptides will help in the identification of potential complications in CKD patients with or without renal replacement therapies and probably improve outcome of these patients.

Cardiovascular disease in patients with chronic renal impairment: role of natriuretic peptides

Although there is overwhelming evidence that natriuretic peptides might be helpful in the diagnosis and management of congestive heart failure patients, the relationship among brain natriuretic peptides (BNP), renal function, and the severity of heart failure is less clear. It is obvious that the metabolism and elimination of BNP and N-terminal prohormone brain natriuretic peptide (NT-proBNP) are different with BNP clearance less dependent upon renal function. This paper reviews current data about the diagnostic and predictive role of natriuretic peptides to detect cardiac events in patients with chronic kidney disease. Although BNP and Nt-proBNP can be used to diagnose acute heart failure and may help predict risk and future cardiac events in patients with chronic kidney disease (CKD), a strategy that incorporates their use in daily clinical practice is still lacking.

N-terminal Pro-B–Type Natriuretic Peptide (NT-proBNP) Concentrations in Hemodialysis Patients: Prognostic Value of Baseline and Follow-up Measurements

Background: Increased N-terminal pro-B–type natriuretic peptide (NT-proBNP) concentrations are associated with increased cardiovascular mortality in chronic hemodialysis patients. Previous studies focused on prevalent dialysis patients and examined single measurements of NT-proBNP in time.

Methods: We measured NT-proBNP concentrations in 2990 incident hemodialysis patients to examine the risk of 90-day and 1-year mortality associated with baseline NT-proBNP concentrations. In addition, we calculated the change in concentrations after 3 months in a subset of 585 patients to examine the association between longitudinal changes in NT-proBNP and subsequent mortality.

Results: Increasing quartiles of NT-proBNP were associated with a monotonic increase in 90-day [quartile 1, referent; from quartile 2 to quartile 4, hazard ratio (HR) 1.7–6.3, P &lt; 0.001] and 1-year (quartile 1, referent; from quartile 2 to quartile 4, HR 1.7–4.9, P &lt; 0.001) all-cause mortality. After multivariable adjustment, these associations remained robust. When examined using a multivariable fractional polynomial, increased NT-proBNP concentrations were associated with increased 90-day (HR per unit increase in log NT-proBNP 1.5, 95% CI 1.3–1.7) and 1-year (HR per unit increase in log NT-proBNP 1.4, 95% CI 1.3–1.5) all-cause mortality. In addition, patients with the greatest increase in NT-proBNP after 3 months of dialysis had a 2.4-fold higher risk of mortality than those with the greatest decrease in NT-proBNP.

Conclusions: NT-proBNP concentrations are independently associated with mortality in incident hemodialysis patients. Furthermore, the observation that longitudinal changes in NT-proBNP concentrations were associated with subsequent mortality suggests that monitoring serial NT-proBNP concentrations may represent a novel tool for assessing adequacy and guiding therapy in patients initiating hemodialysis.

B-type natriuretic peptides strongly predict mortality in patients who are treated with long-term dialysis

BACKGROUND AND OBJECTIVES

Left ventricular abnormalities contribute to cardiovascular disease in patients with chronic kidney disease and may be detected by measurement of B-type natriuretic peptide in serum.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a prospective cohort study of predialysis patients, patients who were on dialysis, and kidney transplant recipients, serum was collected and assayed for both B-type natriuretic peptide and its N-terminal fragment. Median levels were compared using nonparametric tests, and predictors of B-type natriuretic peptide were determined by linear regression. Survival analysis and Cox regression were performed to examine the association of levels of B-type natriuretic peptide with cardiovascular events and death.

RESULTS

Levels of B-type natriuretic peptide were highest in patients who were on dialysis. Patients who were receiving dialysis and had known cardiovascular disease, were not on the waiting list for kidney transplantation, or had left ventricular systolic dysfunction on echocardiography had significantly higher levels of B-type natriuretic peptide than patients without these characteristics. Glomerular filtration rate was an important predictor of B-type natriuretic peptide levels for patients who were not on dialysis (predialysis and renal transplant recipients). Left ventricular systolic dysfunction predicted B-type natriuretic peptide levels in patients who were on dialysis. Both forms of B-type natriuretic peptide were associated with a two- to three-fold increased risk for death in patients who were on dialysis.

CONCLUSIONS

Levels of B-type natriuretic peptide are greatest in patients who are on dialysis and have cardiovascular comorbidities and are strong predictors of death.

N-terminal prohormone brain natriuretic peptide as a predictor of cardiovascular disease and mortality in blacks with hypertensive kidney disease: the African American Study of Kidney Disease and Hypertension (AASK)

BACKGROUND

Higher levels of N-terminal prohormone brain-type natriuretic peptide (NT-proBNP) predict cardiovascular disease (CVD) in several disease states, but few data are available in patients with chronic kidney disease or in blacks.

METHODS AND RESULTS

The African American Study of Kidney Disease and Hypertension trial enrolled hypertensive blacks with a glomerular filtration rate of 20 to 65 mL x min(-1) x 1.73 m(-2) and no other identified cause of kidney disease. NT-proBNP was measured with a sandwich chemiluminescence immunoassay (coefficient of variation 2.9%) in 994 African American Study of Kidney Disease and Hypertension participants. NT-proBNP was categorized as undetectable, low, moderate, or high. Proteinuria was defined as 24-hour urinary protein-creatinine ratio >0.22. A total of 134 first CVD events (CVD death or hospitalization for coronary artery disease, heart failure, or stroke) occurred over a median of 4.3 years. Participants with high NT-proBNP were much more likely to have a CVD event than participants with undetectable NT-proBNP after adjustment (relative hazard 4.0 [95% confidence interval [CI] 2.1 to 7.6]). A doubling of NT-proBNP was associated with a relative hazard of 1.3 (95% CI 1.0 to 1.6) for coronary artery disease, 1.7 (95% CI 1.4 to 2.2) for heart failure, 1.1 (95% CI 0.9 to 1.4) for stroke, and 1.8 (95% CI 1.4 to 2.4) for CVD death. The association of NT-proBNP with CVD events was significantly stronger (P(interaction)=0.05) in participants with than in those without proteinuria. Higher NT-proBNP was not associated with renal disease progression.

CONCLUSIONS

These results suggest that elevated NT-proBNP levels are associated with higher CVD risk among blacks with hypertensive kidney disease. This association may be stronger in individuals with significant proteinuria.

Amino-terminal pro-B-type natriuretic peptide testing in renal disease

Concentrations of amino-terminal pro-B-type natriuretic peptides (NT-proBNP) are typically higher in patients with chronic kidney disease (CKD) than in those without CKD. These elevated levels of NT-proBNP in patients with CKD do not simply reflect the reduced clearance of the peptide; rather, they largely reflect a true-positive finding, identifying the presence of heart disease in these patients, while similarly indicating prognosis as well. Although modestly stronger inverse correlations exist between renal function and NT-proBNP compared with B-type natriuretic peptide (BNP), the dependence of both peptides on renal clearance is similar. Across the range of CKD, correlations between BNP and NT-proBNP remain strong, and the prognostic impact of NT-proBNP in patients with CKD is preserved. When evaluating the patient with acute dyspnea and CKD, both BNP and NT-proBNP are affected similarly, with higher decision limits necessary compared with patients with preserved renal function. Importantly, when using NT-proBNP to evaluate a patient with dyspnea and impaired renal function, the recommended cut points of 450, 900, and 1,800 ng/L for those aged <50, 50-75, and >75 years, respectively, do not require further adjustment for renal function. Thus, NT-proBNP testing remains useful for the diagnostic and prognostic evaluation of patients with CKD.

Relationships of N-terminal pro-B-natriuretic peptide and cardiac troponin T to left ventricular mass and function and mortality in asymptomatic hemodialysis patients

BACKGROUND

Although the cardiac biomarker troponin T (cTnT) is related strongly to mortality in patients with end-stage renal disease, the independent association of N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) and cTnT levels in predicting outcomes is unknown. The objective of this study is to determine factors associated with NT-pro-BNP and cTnT and determine whether these levels are associated with mortality.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

Asymptomatic hemodialysis patients (n = 150) in 4 university-affiliated hemodialysis units. EXPOSURE & OUTCOMES: For cross-sectional analysis, echocardiographic variables as exposures and NT-pro-BNP and cTnT levels as outcomes; for longitudinal analysis, association of NT-pro-BNP and cTnT levels as exposures to all-cause and cardiovascular disease mortality as outcomes.

RESULTS

In a multivariate regression analysis, low midwall fractional shortening, a measure of poor systolic function, was an independent correlate of log NT-pro-BNP level (P < 0.01), whereas left ventricular mass index was an independent correlate of cTnT level (P < 0.01). During a median follow-up of 24 months, 46 patients died, 26 of cardiovascular causes. NT-pro-BNP levels had a strong graded relationship with all-cause (hazard ratios [HRs], 1.54, 4.78, and 4.03 for increasing quartiles; P < 0.001) and cardiovascular mortality (HRs, 2.99, 10.95, and 8.54; P < 0.01), whereas cTnT level had a weaker relationship with all-cause (HRs, 1.57, 2.32, and 3.39; P < 0.01) and cardiovascular mortality (HRs, 0.81, 2.12, and 2.14; P = 0.1). The combination of the 2 biomarker levels did not improve the association with all-cause or cardiovascular mortality compared with NT-pro-BNP level alone. NT-pro-BNP level was a marker of mortality even after adjusting for left ventricular mass index and midwall fractional shortening.

LIMITATIONS

Our cohort was predominantly black and of limited sample size.

CONCLUSION

NT-pro-BNP level strongly correlates with left ventricular systolic dysfunction and is associated more strongly with mortality than cTnT level in asymptomatic hemodialysis patients.

Measuring risk in end-stage renal disease: is N-terminal pro brain natriuretic peptide a useful marker?

Natriuretic peptides are important in the maintenance of body volume homeostasis. There has been interest in utilizing the levels of these peptides to diagnose and prognosticate cardiovascular disease. In end-stage renal disease, the diagnostic utility of these peptides is limited. Madsen et al. report that levels of N-terminal pro brain natriuretic peptide (NT-proBNP) levels offer important information on the risk of mortality in patients undergoing hemodialysis.