Antibiotic Timing as a Quality-of-Care Metric in ICU Pneumonia: Association With In-Hospital Mortality and Microbiological Confirmation.

BACKGROUND: Timely antibiotic therapy is recommended for critically ill patients with pneumonia and is widely used as a quality-of-care indicator. However, its independent association with in-hospital mortality remains uncertain after adjustment for illness severity, empirical antibiotic therapy, and microbiological confirmation. METHODS: This retrospective cohort study included 7515 adult ICU patients with pneumonia from the MIMIC-IV v2.2 database who received systemic antibiotic therapy. Antibiotic timing was categorized as <1 h, 1-3 h, and >3 h after hospital admission. The primary outcome was in-hospital mortality. Multivariable logistic regression adjusted for age, sex, SOFA score, Charlson Comorbidity Index, invasive mechanical ventilation, vasopressor therapy, microbiological confirmation, and empirical antibiotic therapy. Sensitivity, subgroup, and interaction analyses were performed. RESULTS: Crude in-hospital mortality was similar across antibiotic timing groups (21.8%, 22.4%, and 21.7% for <1 h, 1-3 h, and >3 h, respectively; p = 0.791). After adjustment, neither antibiotic administration within 1-3 h (adjusted OR 0.98, 95% CI 0.79-1.21; p = 0.873) nor >3 h (adjusted OR 1.02, 95% CI 0.83-1.25; p = 0.847) was independently associated with in-hospital mortality. Microbiological confirmation was also not independently associated with mortality (adjusted OR 1.10, 95% CI 0.95-1.28; p = 0.198). All additional analyses produced consistent results. CONCLUSIONS: After adjustment for illness severity, comorbidity burden, microbiological confirmation, organ support, and empirical antibiotic therapy, antibiotic timing was not independently associated with in-hospital mortality. Antibiotic timing alone should not be considered a comprehensive quality-of-care metric in critically ill patients with pneumonia.