Effect modification by chronic obstructive pulmonary disease, anion gap, and serum creatinine on the association between invasive mechanical ventilation and 28-day mortality in intensive care unit sepsis patients: a retrospective cohort study.

Background: Sepsis remains a leading cause of mortality in intensive care units (ICUs) worldwide, affecting millions of patients annually. Although mechanical ventilation (MV) is a life-saving intervention in sepsis management, its association with patient outcomes remains controversial, with conflicting evidence regarding its impact on mortality. Current literature lacks a comprehensive analysis of the clinical phenotypes and laboratory parameters that may modify this relationship. This study aimed to evaluate the association between MV and 28-day mortality in ICU sepsis patients and to explore potential effect modifiers. Methods: We conducted a retrospective cohort study of adult sepsis patients admitted to the ICU of Fuqing Affiliated Hospital, Fujian Medical University, between January 1, 2017, and December 31, 2024. Sepsis was defined according to Sepsis-3 criteria. The primary exposure was invasive mechanical ventilation, and the primary outcome was 28-day all-cause mortality. Covariates included 25 variables encompassing demographics, seven comorbidities, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, vital signs, eleven laboratory parameters, and antibacterial therapy. We performed multi-variable logistic regression adjusting for these covariates to assess the MV-mortality association, with stratified analyses and interaction terms to evaluate effect modification. Results: Among 673 ICU sepsis patients, 507 (75.3%) received mechanical ventilation. The 28-day mortality rate was significantly higher in the MV group than in the non-ventilation group (56.0% vs. 29.5%, Conclusion: Mechanical ventilation is independently associated with 28-day mortality in ICU sepsis patients, particularly in those with an elevated anion gap, lower serum creatinine, and without COPD. These findings highlight the importance of judicious MV use in sepsis patients and support individualized patient assessment and tailored respiratory management strategies in clinical practice. Clinical trial registration: Identifier ChiCTR2500109053 https://www.chictr.org.cn/showproj.html?proj=283223.