Relationship between time-weighted average anion gap and mortality in septic shock patients: a retrospective analysis of the MIMIC-IV database.

BACKGROUND

The relationship between the anion gap (AG) level, represented by the time-weighted average AG (TWA-AG), and outcomes of septic shock patients remains unclear. This study aimed to investigate the relationship between TWA-AG and all-cause mortality in septic shock patients.

METHODS

This study included septic shock patients from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Participants were categorized into four quartiles based on their TWA-AG values. The primary outcome was 30-day mortality, and the secondary outcomes were in-hospital and 1-year mortality. Cox regression models, logistic regression models, and restricted cubic spline analyses were conducted to evaluate the relationship between TWA-AG and mortality.

RESULTS

After adjustment for all potential confounders, the association of TWA-AG, as a continuous variable, with 30-day mortality remained significant, with an adjusted hazard ratio (HR) of 1.06 (95% confidence interval [CI]: 1.04-1.07, P < 0.001). Compared to the first quartile group, the HR with 95% CI for the second, third, and fourth quartile groups were 1.25 (1.06-1.48), 1.44 (1.22-1.69), and 1.89 (1.58-2.27), respectively. A similar relationship was also found for in-hospital mortality and 1-year mortality. A linear relationship was observed between the TWA-AG and mortality. When TWA-AG was integrated into the conventional disease severity scoring systems, the predictive ability of these systems was significantly enhanced.

CONCLUSIONS

Elevated TWA-AG is independently associated with increased all-cause mortality in septic shock patients. TWA-AG may be a promising prognostic marker for septic shock patients.