Associations between initial antimicrobial therapy and medical outcomes for hospitalized elderly patients with pneumonia

Background: Although medical practice guidelines exist, there have been no large-scale studies assessing the relationship between initial antimicrobia l therapy and medical outcomes for patients hospitalized with pneumonia. Objective: To determine the associations between initial antimicrobial ther apy and 30-day mortality for these patients. Methods: Hospital records for 12 945 Medicare inpatients (165 years of age) with pneumonia were reviewed. Associations between initial antimicrobial r egimens and 30-day mortality were assessed with Cox proportional hazards mo dels, adjusting for baseline differences in patient characteristics, illnes s severity, and processes of care. Comparisons were made with patients trea ted with a non-pseudomonal third-generation cephalosporin alone (the refere nce group). Results: Initial treatment with a second-generation cephalosporin plus macr olide (hazard ratio [HR], 0.71; 95% confidence interval [CI], 0.52-0.96), a non-pseudomonal third-generation cephalosporin plus macrolide (HR, 0.74; 9 5% CI, 0.60-0.92), or a fluoroquinolone alone (HR, 0.64; 95% CI, 0.43-0.94) was independently associated with lower 30-day mortality. Adjusted mortali ty among patients initially treated with these 3 regimens became significan tly lower than that in the reference group beginning 2, 3, and 7 days, resp ectively, after hospital admission. Use of a beta-lactam/beta-lactamase inh ibitor plus macrolide (HR, 1.77; 95% CI, 1.28-2.46) and an aminoglycoside p lus another agent (HR, 1.21; 95% CI, 1.02-1.43) were associated with an inc reased 30-day mortality. Conclusions: In this study of primarily community dwelling elderly patients hospitalized with pneumonia, 3 initial empiric antimicrobial regimens were independently associated with a lower 30-day mortality. The more widesprea d use of these antimicrobial regimens is likely to improve the medical outc omes for elderly patients with pneumonia.