Empiric antibiotic therapy and mortality among medicare pneumonia inpatients in 10 western states : 1993, 1995, and 1997.

STUDY OBJECTIVES To examine the association of empiric inpatient antibiotic treatment of community-acquired pneumonia (CAP) with mortality, and whether this association varies from year to year. DESIGN Population-based, retrospective study adjusting for demographics, comorbidities, and clinical characteristics. SETTING Acute-care hospitals in 10 western states. PATIENTS A group of 10,069 Medicare beneficiaries aged > or = 65 years who were hospitalized with CAP during fiscal years 1993, 1995, and 1997. MEASUREMENTS AND RESULTS We examined the risk for mortality during the 30 days after admission to the hospital. The impact of specific antibiotic regimens varied greatly from year to year. In 1993, therapy with a macrolide plus a beta-lactam was associated with significantly lower mortality than therapy with either a beta-lactam alone (adjusted odds ratio [AOR], 0.42; 95% confidence interval [CI], 0.25 to 0.69) or other regimens that did not include a macrolide, beta-lactam, or fluoroquinolone (AOR, 0.35; 95% CI, 0.20 to 0.62). Those associations were not observed in 1995 or 1997. Lower mortality was associated with fluoroquinolone monotherapy compared with beta-lactam monotherapy in 1997 (AOR, 0.27; 95% CI, 0.07 to 0.96) and with macrolide monotherapy compared with other regimens in 1995 (AOR, 0.24; 95% CI, 0.06 to 0.93), but the number of patients who received these regimens was small. CONCLUSIONS The inclusion of a macrolide or a fluoroquinolone in initial empiric CAP treatment was associated with improved survival, but this association varied from year to year, perhaps as a result of a temporal variation in the incidence of atypical pathogen pneumonia. Improved testing and surveillance for atypical pathogen pneumonia are needed to guide empiric therapy.