The utility of brain natriuretic peptide as a prognosticating marker in critical care patients

Background. Brain natriuretic peptide (BNP) is an established biomarker of morbidity and mortality in cardiac failure. Data also suggest potential prognostic utility in non-heart failure cohorts. The utility of BNP in predicting intensive care unit (ICU) outcomes has not been well evaluated in a mixed critical care population in the South African (SA) context. Objective. To evaluate the ability of BNP to predict ICU mortality in a heterogeneous critical care population in SA. Methods. This was a retrospective observational study of 100 patients admitted to a multidisciplinary, closed, intensivist-run ICU in a tertiary academic hospital serving KwaZulu-Natal Province (1 January 2020 - 31 July 2022). Initial BNP was evaluated as a predictor of ICU mortality using univariate and multivariable analyses. Results. There was a statistically significant difference in BNP between survivors and non-survivors in the cohort of patients without heart failure. The median initial BNP in the non-heart failure cohort was 411 (interquartile range (IQR) 116 - 848) ng/L in non-survivors, and 150 (44 - 356) ng/L in survivors (p=0.028). The optimal cut-off for BNP was determined as 366 ng/L. A BNP ≥366 ng/L was an independent predictor of ICU outcome. Conclusion. This study highlights the potential utility of BNP as a predictor of ICU mortality in a heterogeneous ICU population, with the greatest utility in patients without heart failure. Further studies are required to confirm this finding.