Associations between pneumonia with sepsis, sepsis-associated encephalopathy, and mortality in adult intensive care unit: a retrospective analysis using MIMIC-IV database.

BACKGROUND: Pneumonia is a common pulmonary infection that can lead to sepsis and sepsis-associated encephalopathy (SAE), both of which are associated with increased mortality. This study aimed to examine the relationship between pneumonia and sepsis, as well as SAE, and to determine the association between pneumonia and patient mortality. METHODS: A retrospective study was conducted based on the data attained from the Medical Information Mart for Intensive Care-IV database (version 3.1). Patients' demographics, comorbidities, laboratory results, clinical characteristics, and 30-day mortality were extracted for patients admitted to the intensive care unit (ICU). Univariate and multivariate regression analyses were performed to assess the associations between pneumonia and sepsis, pneumonia and SAE, and pneumonia and 30-day mortality, both in the entire cohort and subgroups. RESULTS: A total of 46,061 patients were included in the analysis, of whom 7,289 (15.82%) had pneumonia and 38,772 (84.18%) did not. Among pneumonia patients, 5,700 (78.20%) developed sepsis, and 4,250 (58.31%) developed SAE, with a significantly higher mortality rate compared to non-pneumonia patients (25.79% vs. 11.65%, P<0.001). Regression analysis revealed that pneumonia was associated with sepsis [hazard ratio (HR), 1.22, 95% confidence interval (CI), 1.18-1.25], SAE [odds ratio (OR), 1.55, 95% CI, 1.44-1.67], and 30-day mortality (HR, 1.19, 95% CI, 1.12-1.27), all of which all associations were statistically significant (P<0.001). Subgroup analysis indicated that the association between pneumonia and sepsis, SAE, and 30-day mortality remained significant across most subgroups, although demographic and clinical factors influenced these relationships. Multicollinearity and sensitivity analyses confirmed the robustness of the findings. CONCLUSIONS: Pneumonia significantly increased the risk of developing sepsis and SAE, as well as the risk of 30-day mortality in ICU patients. These risks may be modulated by various patient demographic and clinical factors.