Broad-spectrum antibiotic use and poor outcomes in community-onset pneumonia: a cohort study.

Question Is broad-spectrum antibiotic use associated with poor outcomes in community-onset pneumonia after adjusting for confounders? Methods Retrospective, observational cohort study of 1995 adults with pneumonia admitted from 4 United States hospital emergency departments. We used multivariable regressions to investigate the effect of broad-spectrum antibiotics on 30-day mortality, length of stay, cost, and Clostridioides difficile infection. To address indication bias, we developed a propensity score using multilevel (individual provider) generalised linear mixed models to perform inverse-probability of treatment weighting (IPTW) to estimate the average treatment effect in the treated (ATT). We also manually reviewed a sample of mortality cases for antibiotic-associated adverse events. Results 39.7% of patients received broad-spectrum antibiotics, but drug-resistant pathogens were recovered in only 3%. Broad-spectrum antibiotics were associated with increased mortality in both the unweighted multivariable model ( OR 3.8, CI 2.5–5.9, p OR 4.6, CI 2.9–7.5, p C. difficile infection. Healthcare- associated pneumonia (HCAP) was not associated with mortality independent of broad-spectrum antibiotic use. In manual review we identified antibiotic-associated events in 17.5% of mortality cases. Conclusion Broad-spectrum antibiotics appear to be associated with increased mortality and other poor outcomes in community-onset pneumonia.