Brain Natriuretic Peptide between Traditional and Nontraditional Risk Factors in Hemodialysis Patients: Analysis of Cardiovascular Mortality in a Two-Year Follow-Up

Abstract

Background: The ability of brain natriuretic peptide (BNP) together with other traditional and nontraditional risk factors to predict cardiovascular (CV) mortality in hemodialysis (HD) patients has not been well established. The aim of this prospective study was to determine the predictive cutoff values of baseline measurement of BNP along with the known CV disease risk factors to predict all-cause and CV mortality in HD patients. Methods: BNP concentration before HD was measured in 125 prevalent HD patients (age 53.0 ± 13.5 years, HD vintage 75.2 ± 61.0 months). In addition, several traditional CV risk factors (blood pressure, dyslipidemia, diabetes mellitus, body mass index, left ventricular hypertrophy) and uremia/dialysis-related CV risk factors (anemia, calcium and phosphate impairment, malnutrition, inflammation, ultrafiltration, HD duration, Kt/V) were examined. Results: During the 2-year follow-up, we lost 28 out of 125 patients (22.5%), with CV disease (65.7%) being the main cause of mortality. The cutoff point for BNP, as predictor of the clinical outcome, according to the ROC curve was 1,194 pg/ml for CV mortality with sensitivity and specificity of 63 and 65%, respectively (AUC 0.61 and confidence interval (CI) 95% 0.47–0.75). Kaplan-Meier analysis showed that all-cause (log-rank, p = 0.002) and CV mortality (log-rank, p = 0.001) were the cause of a significantly lower survival in patients with a mean BNP >1,200 pg/ml. The univariate Cox regression analysis found the following factors to be predictors of all-cause mortality: hemoglobin (<110 g/l), phosphorus (>1.78 mmol/l), albumin (<40 g/l), C-reactive protein (CRP ≧10 mg/l), BNP (>1,200 pg/ml) and cardiac ejection fraction (≤55%). The multivariate Cox regression analyses demonstrated that only CRP ≧10 mg/l with a hazard ratio (HR) 6.82 (CI 95% 1.86–24.9, p = 0.004) and BNP >1,200 pg/ml with HR 5.79 (CI 95% 1.58–21.3, p = 0.004) were predictors of all-cause mortality. BNP >1,200 pg/ml with HR 13.52 (CI 95% 1.68–108.9, p = 0.014) was found to be an even stronger predictor of CV mortality than CRP ≧10 mg/l with HR 6.53 (CI 95% 1.35–31.6, p = 0.020). Conclusions: Our study pointed out that BNP >1,200 pg/ml as a marker of cardiac dysfunction and CRP ≧10 mg/l as a marker of inflammation identify HD patients at increased risk of CV mortality.