Association Between Empirical Anti-Pseudomonal Antibiotics for Recurrent Lower Respiratory Tract Infections and Mortality: A Retrospective Cohort Study

Purpose: Whether the empirical use of anti-pseudomonal antibiotics actually improves patient outcomes is unclear. Hence, we aimed to determine whether empirical anti-pseudomonal antibiotics are better than anti-pseudomonal antibiotics in treating patients with recurrent lower respiratory tract infections (LRTIs).

Patients and methods: We extracted data from the Japanese nationwide database of the Real World Data Co., Ltd. Our target population was patients with LRTIs, defined as chronic obstructive pulmonary disease exacerbation and pneumonia. We included patients aged ≥40 years who were admitted for lower respiratory tract infections ≥2 times within 90 days. We excluded patients who had an event (death or transfer) within 24 h after admission. We ran a frailty model adjusted for the following confounding factors: number of recurrences, age, body mass index, activities of daily living, Hugh-Johns classification, altered mental status, oxygen use on admission, blood urea nitrogen, and systemic steroid use.

Results: We included 893 patients with 1362 observations of recurrent LRTIs. There were 897 (66%) observations in the non-anti-pseudomonal antibiotic group and 465 (34%) in the anti-pseudomonal group; the numbers of in-hospital deaths were 86/897 (10%) and 63/465 (14%), respectively. Our frailty model yielded an adjusted hazard ratio (HR) (anti-pseudomonal group/non-anti-pseudomonal group) of 1.49 (95% confidence interval, 1.03-2.14).

Conclusion: The empirical use of anti-pseudomonal antibiotics was associated with a higher HR of in-hospital mortality than the use of non-anti-pseudomonal antibiotics. Physicians might need to consider limiting the prescription of anti-pseudomonal antibiotics based on background factors such as the patient's baseline function and disease severity. Further studies are needed to evaluate the causal relationship between empirical anti-pseudomonal antibiotics and mortality, and identify specific patient population who benefit from empirical anti-pseudomonal antibiotics.