Association of serum anion gap with 28-day mortality in critically ill patients with pneumothorax: A retrospective cohort study utilizing the MIMIC-IV database.

BACKGROUND

Pneumothorax in intensive care units (ICU) patients is frequently associated with increased mortality. The serum anion gap (AG) is widely used in clinical practice as an indicator of acid-base disturbances and metabolic acidosis. The association between serum AG and 28-day mortality in critically ill patients with pneumothorax has not been well established.

OBJECTIVE

This study aims to investigate the impact of serum AG on 28-day mortality in critically ill patients with Pneumothorax.

METHODS

A retrospective cohort study was conducted involving 1844 participants diagnosed with Pneumothorax and admitted to ICU. Vital signs, laboratory parameters and comorbidities were collected for all participants to analyze the association between AG levels and 28-day mortality.

RESULTS

A total of 1844 critically ill patients with pneumothorax were included in the study. The mean age was 59.6 years, and 62.4 % were male. The overall 28-day mortality rate was 16.5 %. A greater AG on admission was significantly associated with increased 28-day mortality in unadjusted analysis (hazard ratio [HR] 1.13; 95 % confidence interval [CI] 1.12-1.15; p < 0.001). After adjusting for all confounders, the association remained significant (adjusted HR 1.04; 95 % CI 1.01-1.07; p = 0.003). When AG was converted into categorical variables (quartiles), the risk of 28-day mortality in the greatest Q4 group was significantly higher compared with that in the lowest Q1 group (Model 4: HR = 3.3, 95%CI: 1.89-5.75, p < 0.001).

CONCLUSION

A greater AG on admission was independently associated with increased 28-day mortality in critically ill patients with pneumothorax.Further research is needed to explore the underlying mechanisms of these associations.