Association between base excess and mortality in patients with congestive heart failure

Abstract

Aims: The relationship between baseline base excess (BE) and survival outcomes in patients with congestive heart failure (CHF) is unclear. Therefore, we aimed to investigate this relationship based on the Multiparameter Intelligent Monitoring in Intensive Care III (MIMIC-III) database (v1.4).

Methods and results: This retrospective cohort study included 5956 adult patients with CHF from the MIMIC-III database from 2001 to 2012. Using the Cox proportional-hazard analysis and Kaplan-Meier plot, we evaluated the relationship between baseline BE and all-cause death at 1 year after admission to the intensive care unit. At the 1 year follow-up, 2104 participants (35.3%) had died. There was an association between BE and all-cause death (log-rank test P < 0.0001). In the Cox regression model adjusted for demographic and clinical variables, the risk of all-cause death in the first (BE ≤ -8), second (-8 < BE ≤ -3), fourth (2 < BE ≤ 7), and fifth (BE > 7) BE groups was significantly higher than that in the third BE group (-3 < BE ≤ 2) [hazard ratio (HR) 1.99, 95% confidence interval (CI) 1.62-2.43, HR 1.40, 95% CI 1.23-1.60, HR 1.46, 95% CI 1.26-1.69, and HR 1.68, 95% 1.33-2.12, respectively]. Similar results were observed when BE was modelled as a continuous variable using a Cox regression model with a restricted cubic spline.

Conclusions: This study demonstrated the existence of a U-shaped relationship between BE and survival outcome in patients with CHF. Both low and high BE increased the risk of all-cause mortality.

Keywords: Base excess; Congestive heart failure; Mortality; Regression analysis.