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.