Association between base excess and mortality in critically ill patients with ischemic stroke: a retrospective cohort study

Base excess (BE) is associated with mortality from many diseases. However, the relationship between BE and mortality in patients with ischemic stroke remains uncertain. Our aim is to investigate the relationship between BE values upon admission to the ICU and mortality rates in critically ill stroke patients. The current study enrolled 1,572 patients with ischemic stroke (863 males and 709 females). The associations of BE with intensive care unit (ICU), hospital, 28-day, and 1-year mortalities were assessed using multivariable logistic regression or Cox proportional hazards model. The potential impact of the Sequential Organ Failure Assessment (SOFA) score (< 5 or ≥ 5) on the prognostic value of BE was further evaluated with interaction and subgroup analyses. BE values less than − 3 mmol/L, greater than 3 mmol/L, and within − 3 to 3 mmol/L (normal BE) were observed in 316 (20.1%), 175 (11.1%), and 1,081 (68.8%) patients, respectively. The restricted cubic splines analyses revealed that a U-shaped curve between BE and the mortality risk. Multivariable analysis indicated that patients with low BE (<-3 mmol/L) had higher rates of ICU mortality (odds ratio [OR], 1.829; 95% confidence interval [CI], 1.281–2.612; P = 0.001), hospital mortality (OR, 1.484; 95% CI, 1.077–2.045; P = 0.016), 28-day mortality (hazard ratio [HR], 1.522; 95% CI, 1.200–1.929; P = 0.001), and 1-year mortality (HR, 1.399; 95% CI, 1.148–1.705; P = 0.001) than patients with normal BE. Subgroup analyses showed consistent results pertaining to SOFA scores ≥ 5. In critically ill patients with ischemic stroke, an initial BE of <-3 mmol/L at ICU admission may indicate an increased risk of ICU, hospital, 28-day, and 1-year mortalities.