AB035. Use of antibiotics among patients hospitalized for exacerbations of asthma

Background: Guidelines discourage routine administration of antibiotics during exacerbations of asthma, however little is known about treatment patterns in clinical practice. To determine the frequency of antibiotic use in the management of patients hospitalized for asthma and to identify factors associated with treatment.

Methods: Design: retrospective cohort study of hospitalizations for asthma in 2013 and 2014. Setting: 576 US hospitals. Participants: inpatient and observation cases >18 years with a principal diagnosis of asthma or a principal diagnosis of acute respiratory failure combined with a secondary diagnosis of asthma. Patients with indications for antibiotic therapy were excluded. Main outcome: we assessed the receipt, timing, type, and duration of antibiotic therapy. We developed a multivariable hierarchical model to identify factors independently associated with use of antibiotics.

Results: Among 68,707 cases, the median age was 56 years, 71% were female and 50% identified as White. Antibiotics were prescribed on the first hospital day in 38,215 (56%) cases, and at any point during the hospitalization in 49,096 (71%) cases. Median duration of inpatient treatment was 3 days. The most commonly prescribed antibiotics were quinolones (25%), macrolides (24%), 3rd generation cephalosporins (16%) and tetracyclines (4%). Across 457 hospitals with at least 25 cases of asthma during the study period, the median (IQR) rate of antibiotic use on hospital day 1 was 60% (50–72%). Factors independently associated with antibiotic treatment included a diagnosis of chronic obstructive asthma (OR 1.4; 95% CI, 1.4–1.5), mechanical ventilation (OR 1.1; 95% CI, 1.1–1.2), and being treated at a non-teaching (OR 1.4; 95% CI, 1.1–1.6), rural (OR 1.3; 95% CI, 1.1–1.5), or small (<200 beds compared to >400) hospital (OR 1.3; 95% CI, 1.0–1.5). Factors associated with lower odds included younger age (age <40 compared to >65 years, OR 0.7; 95% CI, 0.7–0.8), Black race compared to White (OR 0.8; 95% CI, 0.7–0.8) and heart failure (OR 0.8; 95% CI, 0.8–0.8). These results were robust in sensitivity analyses that sought to exclude patients with other potential indications for antibiotic treatment.

Conclusions: In contrast to national guidelines, the majority of patients hospitalized for asthma receive antibiotics. These findings suggest a large opportunity to improve antimicrobial stewardship by focusing attention on the overuse of antibiotics in asthma.

Keywords: Asthma; antibiotic; hospitalization; retrospective study