Association of Antibiotic Treatment With Outcomes in Patients Hospitalized for an Asthma Exacerbation Treated With Systemic Corticosteroids

Importance Although professional society guidelines discourage use of empirical antibiotics in the treatment of asthma exacerbation, high antibiotic prescribing rates have been recorded in the United States and elsewhere. Objective To determine the association of antibiotic treatment with outcomes among patients hospitalized for asthma and treated with corticosteroids. Design, Setting, and Participants Retrospective cohort study of data of 21 628 adults hospitalized for asthma exacerbation and treated with systemic corticosteroids in 540 US acute care hospitals from January 1, 2015, through December 31, 2016. Exposures Early antibiotic treatment, defined as treatment with an antibiotic initiated during the first 2 days of hospitalization. Patients not treated with antibiotics or treated on day 2 or later were included in the nontreated/late-treated group. Patients with documented infection diagnosed at admission were excluded. Main Outcomes and Measures The primary outcome measure was hospital length of stay. Other outcomes included treatment failure (initiation of mechanical ventilation, transfer to the intensive care unit after hospital day 1, in-hospital mortality, or readmission for asthma within 30 days of discharge), hospital costs, and antibiotic-related diarrhea. Multivariable adjustment, propensity score matching, propensity weighting, and instrumental variable analysis were used to assess the association of antibiotic treatment with outcomes. Results Of the 21 628 patients, the median (interquartile range [IQR]) age was 46 (33-59) years, 15 662 (72.4%) were women and 9616 (44.5%) were White, and Medicare was the primary form of health insurance for 5499 (25.4%). Antibiotics were prescribed for 8927 patients (41.3%) on day 1; 3022 patients (14.0%) were started after day 1. Compared with patients not treated with antibiotics or treated after day 1, patients treated with antibiotics on day 1 were older (median [IQR] age, 48 [35-60] vs 45 [32-57] years), more likely to be White (48.7% vs 41.5%) and smokers (4.5% vs 3.2%), and had a higher number of comorbidities (eg, congestive heart failure, 5.7% vs 5.4%). Those treated with antibiotics on day 1 had a statistically significant longer hospital stay compared with those not treated on day 1 (mean [SD], 2.81 [2.27] vs 2.57 [2.45] days; difference, 0.11 days, 95% CI, 0.03 to 0.19; median [IQR] 2 [1-4] vs 2 [1-3] days). In propensity score–matched analysis, receipt of antibiotics on day 1 was associated with a marginally longer but not clinically meaningful increase in hospital stay (length of stay ratio, 1.06; 95% CI, 1.04 to 1.09), higher cost of hospitalization (median [IQR] cost, $4320 [$2754-$6716] vs $3861 [$2479-$6236]) but lower risk of treatment failure (7.1% vs 8.2%; difference, −1.08%, 95% CI, −1.93% to −0.24%; adjusted OR, 0.86; 95% CI, 0.77 to 0.97). Multivariable adjustment, propensity score weighting, and instrumental variable analysis yielded similar results. Conclusions and Relevance Among adult patients hospitalized for asthma exacerbation and treated with corticosteroids, antibiotic therapy initiated on day 1 of hospitalization was associated with a slightly longer but not clinically important increase in hospital length of stay, higher hospitalization cost, and lower risk of treatment failure. These findings highlight the need to perform randomized clinical trials to determine the role of antibiotic prescribing among patients hospitalized for asthma exacerbation.