Comparison of two guideline-concordant antimicrobial combinations in elderly patients hospitalized with severe community-acquired pneumonia

OBJECTIVE: Two of the guideline-concordant therapies for severe community-acquired pneumonia are either a beta-lactam and fluoroquinolone or beta-lactam and macrolide. However it is unclear if there is a benefit for one vs. The other for elderly patients with severe community-acquired pneumonia. DESIGN: A retrospective population-based cohort study of patients with community-acquired pneumonia. SETTING: Patients admitted to an intensive care unit of any Department of Veterans Affairs hospital during 5-yr period. PATIENTS: We included only those patients >65 yrs of age admitted to the intensive care unit with community-acquired pneumonia who received either beta-lactam + fluoroquinolone or beta-lactam + macrolide antibiotic therapy for pneumonia. INTERVENTION: Not applicable. MEASUREMENTS: We used multilevel regression models to examine the effect of beta-lactam + fluoroquinolone vs. beta-lactam + macrolide on each of the outcomes after adjusting for potential confounders using propensity scores. MAIN RESULTS: The cohort consisted of 1,989 patients: 98.5% male and a mean age of 74 yrs. For treatment, 44% of subjects received beta-lactam + fluoroquinolone and 56% received beta-lactam + macrolide. Unadjusted 30-day mortality was 27% for beta-lactam + fluoroquinolone and 24% for beta-lactam + macrolide (p = .11). In the multilevel models, the use of beta-lactam + fluoroquinolone was not significantly associated with 30-day mortality (odds ratio 1.05, 95% confidence interval 0.85-1.30). However, the use of beta-lactam + fluoroquinolone was significantly associated with increased mean length of stay (incidence rate ratio 1.30, 95% confidence interval 1.27-1.33). CONCLUSIONS: We found no significant difference for 30-day mortality but did demonstrate an association with increase in length of stay associated with the use of beta-lactam + fluoroquinolone. Randomized controlled trials are needed to determine the most effective antibiotics regimes for patients with severe pneumonia.