Application of a Risk Score to Identify Older Adults with Community-Onset Pneumonia Most Likely to Benefit From Empiric Pseudomonas Therapy

Study Objective: To assess the impact of empiric Pseudomonas pharmacotherapy on 30-day mortality in hospitalized patients with community-onset pneumonia stratified according to their risk (low, medium, or high) of drug-resistant pathogens. Design: Retrospective cohort study. Data Source: Veterans Health Administration database. Patients: A total of 50,119 patients who were at least 65 years of age, hospitalized with pneumonia, and received antibiotics within 48 hours of admission between fiscal years 2002 and 2007. Patients were stratified into empiric Pseudomonas therapy (31,027 patients) and no Pseudomonas therapy (19,092 patients) groups based on antibiotics received during their first 48 hours of admission. Measurements and Main Results: A clinical prediction scoring system developed in 2014 that stratifies patients with community-onset pneumonia according to their risk of drug-resistant pathogens was used to identify patients who were likely to benefit from empiric Pseudomonas therapy as well as those in whom antipseudomonal therapy could be spared; patients were classified into low-risk (68%), medium-risk (21%), and high-risk (11%) groups. Of the 50,119 patients, 62% received Pseudomonas therapy. All-cause 30-day mortality was the primary outcome. Empiric Pseudomonas therapy (adjusted odds ratio 0.72, 95% confidence interval 0.62–0.84) was associated with lower 30-day mortality in the high-risk group but not the low- or medium-risk groups. Conclusion: Application of a risk score for patients with drug-resistant pathogens can identify patients likely to benefit from empiric Pseudomonas therapy. Widespread use of this score could reduce overuse of anti-Pseudomonas antibiotics in low- to medium-risk patients and improve survival in high-risk patients.