Antibiotic therapy for ambulatory patients with community-acquired pneumonia in an emergency department setting

Background: Little attention has been paid to the factors that influence choice of antibiotic therapy for patients with community-acquired pneumonia who are treated on an ambulatory basis in an emergency department setting. Methods: Prospective observational study of all patients who presented to the 6 hospitals for adults in the Capital Health Authority, Edmonton, Alberta, with community-acquired pneumonia (as diagnosed by the emergency department physician) from November 15, 2000, through April 30, 2001, and who were treated on an ambulatory basis. Results: The study population consisted of 768 patients, mean age 51 years. The antibiotics most commonly prescribed were azithromycin (36%), levofloxacin (32%), and clarithromycin (17%). Site of care differences were evident in the frequency of clarithromycin (P < .001) and levofloxacin (P =. 0 1) prescription. Multiple logistic regression analysis showed that older age, presence of chronic obstructive pulmonary disease, antibiotic therapy at the time of presentation, and site of care were factors independently predictive of levofloxacin use (P < .05 for all factors). Levofloxacin prescription did not follow our indications for its use in 51% of the 245 patients who were treated with this antibiotic. The failure, rate (defined as admission to the hospital within 3 weeks of emergency department visit) was low (2.2%). Conclusions: Patient factors and site of care influence the choice of antibiotic therapy in an ambulatory setting, and 50% of levofloxacin use was inappropriate according to our definition.