Prognostic value of N terminal pro B type natriuretic peptide in critically ill patients

Abstract

To investigate whether plasma N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) as measured at admission to intensive care unit (ICU) is an independent predictor of mortality in critically ill patients. A prospective observational study of patients in ICU was conducted . One hundred and twenty patients aged>18 years were included during a 6 month period. Among them 88 patients were enrolled for the study. Plasma NT-pro-BNP samples were obtained at admission to ICU. The acute physiology and chronic health evaluation II(APACHEII) score was calculated within 24 hours after admission based on the worst values up to that point. The final evaluation was 28 day mortality. Thirty five patients died within 28 days of ICU admission, the mortality was 39.8%. In 88 patients , the mean plasma NT-pro-BNP levels (ng/L) were 1 221.7 (78.75 500.0), and that in survivor group was significantly lower than non survivor group [781.8 (78.75 066.6) vs. 2 774.5 ( 166.85 500.0 ), P <0.01]. The mean NT-pro-BNP level (ng/L) in male patients was higher than that in females [1 585.5 (103.75 100.0) vs. 794.5 (78.75 500.0), P <0.05]. There was correlation between gender and NT-pro-BNP levels ( r =-0.224, P <0.05). Patients admitted to the ICU because of a severe infection had higher levels of NT-pro-BNP (ng/L) compared with the rest of the cohorts [3 416.1 (103.7 5 100.0) vs. 883.4 (78.75 500.0), P <0.01]. There was correlation between severe infection at admission to ICU and NT-pro-BNP levels ( r =0.285, P <0.01). Areas under the receiver operating characteristic curves (ROC curves) of NT-pro-BNP and APACHEII score were 0.734[95% confidence interval (95% CI ) 0.6280.840] and 0.747 (95% CI 0.6370.858), respectively. Logistic regression analysis showed that the NT-pro-BNP level> 1 418 ng/L and the APACHEII score were independently associated with 28 day mortality [odds ratio ( OR ) 5.235, 95% CI 1.81915.071; OR 1.105, 95% CI 1.81915.071]. With 1 418 ng/L of NT-pro-BNP as the cutoff value, survival rate was significantly lower in the patients with higher NT-pro-BNP level as compared with those with lower values at admission (χ²=16.9, P <0.01). The ICU NT-pro-BNP level higher than 1 418 ng/L and APACHEII score at admission are independent prognosis markers of early mortality. NT-pro-BNP might serve as a potent early diagnostic and prognostic marker in critically ill patients.