Improvement in clinical and economic outcomes with empiric antibiotic therapy covering atypical pathogens for community-acquired pneumonia patients: a multicenter cohort study.

Objective: To determine the effectiveness of empiric antibiotic regimens covering atypical pathogens with respect to detailed clinical and economic outcomes in community-acquired pneumonia (CAP).

Methods: A population-based, multicenter, retrospective cohort study was conducted from June 2010 to May 2011. Patients with a diagnosis of CAP were enrolled and categorized into two groups according to the initial antibiotic strategy used - covering or not covering atypical pathogens. Regression analysis was performed to assess their clinical outcomes (all-cause mortality, clinical improvement rate after 72 h of antimicrobial therapy, and clinical cure rate) and economic outcomes (length of stay, hospitalization costs, and antibiotic expenditure).

Results: A total of 827 patients met the criteria for CAP; 561 (67.8%) received antibiotics with atypical pathogen coverage (APC group), while 266 (32.2%) did not (non-APC group). Regression analysis revealed that the all-cause mortality was much lower in the APC group than in the non-APC group (0.9% vs. 4.9%, respectively), with an odds ratio (OR) of 0.18 (95% confidence interval (CI) 0.06-0.49). Clinical improvement at 72 h (87.7% vs. 85.0%, p=0.274) and the clinical cure rate (91.1% vs. 88.3%, p=0.213) were more favorable in the APC group, but with no significant difference compared to the non-APC group. Moreover, the APC group had a shorter mean length of stay (APC 10.2 days vs. non-APC 11.6 days, p<0.001). In addition, the mean total hospitalization costs for the APC group were markedly lower compared with the non-APC group (US$ 1172.7 vs. US$ 1510.7; p<0.001).

Conclusion: Antimicrobial treatment covering atypical pathogens for hospitalized CAP patients is associated with reduced mortality and economic burden.