Short Term Prognostic Value of the Rapid B-Type Natriuretic Peptide Assay on Length of Hospitalisation in Congestive Heart Failure Patients Presenting to an Emergency Department in Hong Kong: A Prospective Observational Study

Abstract

Introduction Congestive heart failure is a common disease presentation to the emergency department (ED) and most of these patients require hospitalisation for treatment. The aim of this study was to assess the predictive value of B-type natriuretic peptide (BNP) level measured at the ED with respect to the length of hospital stay (LOS) in patients presenting with congestive heart failure (CHF). We also compared whether the BNP level could be a better predictor of LOS than clinical parameters and attempted to establish a cut-off point of BNP level which could differentiate those CHF patients with short hospital stay from the whole population of CHF patients. Method Patients with clinical features compatible with congestive heart failure were recruited into the study. Point-of-care test for BNP level was performed. The LOS, 6-month readmission and mortality were retrieved from the computer Clinical Management System of the hospital. Pearson's correlation coefficient was used to test the association of BNP level and the LOS, 6-month readmission and mortality rate. Result One hundred and twelve (112) patients were recruited into this study and 20 of them succumbed during hospitalisation. The data of the remaining 92 patients were analysed. The correlation coefficient of BNP level and LOS was 0.088. The correlation coefficient of BNP level and readmission within 6 months was 0.130 while the correlation coefficient of BNP level and 6-month mortality was 0.121. The correlation coefficient of other clinical features and LOS ranged from −0.098 to 0.247. The mean LOS of patients with BNP less than 400 pg/ml was 93.29 hours (95%CI=57.38 to 129.19). The mean LOS of patients with BNP greater than 400 pg/ml was 181.05 hours (95%CI=126.01 to 236.08). Patients with BNP level less than 400 pg/ml tended to have a shorter LOS than those with BNP level greater than 400 pg/ml (p=0.046). Conclusion CHF patients with BNP level measured in the emergency department greater than 400 pg/ml tend to have a longer LOS than patients with BNP level less than 400 pg/ml. BNP is not a good predictor for readmission and mortality of these patients.