Impact of Endotracheal Intubation Timing on Clinical Outcomes in Patients with Severe Pneumonia: A Single-Center Retrospective Cohort Study

Purpose: To compare clinical outcomes between early (< 24 hours) and delayed (≥ 24 hours) mechanical ventilation (MV) in adults with severe pneumonia. Methods: In this single-center, multi-ward retrospective cohort study, 827 adults with severe pneumonia requiring MV were admitted to the intensive care unit (ICU) between January 2022 and December 2024. Patients were divided into an early MV group (< 24 hours after ICU admission) and a delayed MV group (≥ 24 hours after ICU admission) according to the timing of endotracheal intubation. Propensity score matching (PSM) was performed to balance baseline characteristics (age, PSI score, APACHE II score, comorbidities). The primary outcome was 28-day all-cause mortality. Secondary outcomes included ICU length of stay, duration of MV, and incidence of related complications. Results: After PSM, 274 patients were included per group. Compared with the delayed MV, early MV was associated with significantly lower 28-day mortality (42.7% vs 51.8%; HR=0.735, 95% CI: 0.567– 0.954; P=0.032), shorter ICU stay (11 vs 13 days; P=0.043), shorter MV duration (141 vs 145 h; P=0.018), and lower rates of tracheostomy at ICU discharge (30.7% vs 39.4%; P=0.032) and continuous renal replacement therapy (CRRT) requirement (23.4% vs 31.0%; P=0.044). In the unmatched cohort, cox regression showed that early MV was independently associated with lower ICU mortality (HR=0.767, 95% CI: 0.615– 0.956; P=0.018). Conclusion: In critically ill patients with severe pneumonia receiving MV in the ICU, early initiation of invasive mechanical ventilation was associated with lower 28-day mortality. Keywords: severe pneumonia, endotracheal intubation, timing, mechanical ventilation, mortality, propensity score matching