Use of Antibiotics Among Patients Hospitalized for Exacerbations of Asthma

The Centers for Disease Control and Prevention estimates that 37% of all antibiotic use in hospitals may be inappropriate, and reducing unnecessary antibiotic prescribing is now considered an urgent national priority.^1,2 In the United States alone, asthma exacerbations led to 1.8 million emergency department visits and 400 000 hospitalizations annually.³ Although guidelines recommend against prescribing antibiotics during exacerbations of asthma in the absence of concurrent infection, little is known about the use of antibiotics in routine clinical practice.^4,5

We conducted a retrospective study of hospitalizations in 2013 and 2014 at 577 US hospitals that participate in the Premier Alliance database. Patients 18 years or older were included if they had a principal diagnosis of asthma (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] codes 493.0x, 493.1x 493.9x 493.2x, 493.8x, and 493.9x) or a principal diagnosis of acute respiratory failure (ICD-9-CM codes 518.81, 518.82, and 518.84) combined with a secondary diagnosis of asthma. We excluded patients with an admitting or discharge diagnosis of bronchitis, emphysema, chronic obstructive pulmonary disease, or bronchiectasis. We also excluded patients with potential indications for antibiotics, including those with admitting or present-on-admission discharge diagnoses of sinusitis, pneumonia, urinary tract infection, skin and soft-tissue infection, septicemia or sepsis, or fever; those hospitalized for pneumonia within 3 months of the index admission; or those in whom blood or sputum cultures were obtained. The Institutional Review Board at Baystate Medical Center approved the study, which was considered nonhuman subjects research.

For each patient, we assessed receipt, type, and timing of antibiotic therapy. For each hospital, we computed a facility-specific rate of antibiotic treatment. We developed a hierarchical logistic regression model to identify independent patient and hospital factors associated with antibiotic treatment. In a sensitivity analysis, we further restricted the cohort by excluding patients with a diagnosis of infection regardless of present-on-admission status, those 55 years or older, and patients with a diagnosis of tobacco use.

Among 51 951 patients, the median age was 52 years (interquartile range, 39-64 years), 36 527 (70.3%) were female, and 23 728 (45.7%) identified as white (Table). Antibiotics were prescribed on the first hospital day in 21 248 (40.9%) and at any point during the hospitalization in 30 226 patients (58.2%). Median duration of inpatient antibiotic treatment was 3 days (interquartile range, 2-4 days). The most commonly prescribed antibiotics were macrolides (9633 [18.5%]), quinolones (8362 [16.1%]), third-generation cephalosporins (4420 [8.5%]), and tetracyclines (1858 [3.6%]). Treatment rates varied across hospitals (Figure).

Factors associated with lower chance of antibiotic treatment included younger age (adjusted odds ratio [AOR], for <40 years: 0.8; 95% CI, 0.7-0.8; 40-65 years: 0.9; 95% CI, 0.9-1.0 vs >65 years), black race (AOR, 0.8; 95% CI, 0.7-0.8) compared with white race, congestive heart failure (AOR, 0.8; 95% CI, 0.8-0.9), and being treated at a teaching hospital (AOR, 0.7; 95% CI, 0.6-0.8 vs a nonteaching hospital) or a hospital located in the Northeast (AOR, 0.6; 95% CI, 0.5-0.7) or West (AOR, 0.8; 95% CI, 0.6-0.9) compared with the South. Chronic obstructive asthma was associated with an increased likelihood of receiving antibiotic treatment (AOR, 1.6; 95% CI, 1.5-1.7) (Table). These results were robust in sensitivity analysis.

In this large national sample, we found that 58.2% of patients hospitalized for asthma received antibiotics in the absence of documentation of an indication for antibiotic therapy. These findings build on prior research restricted to US emergency departments that reported that 18% to 22% of patients with asthma were given a prescription for an antibiotic on emergency department discharge.⁶

Possible explanations for this high rate of potentially inappropriate treatment include the challenge of differentiating bacterial from nonbacterial infections, distinguishing asthma from chronic obstructive pulmonary disease in the acute care setting, and gaps in knowledge about the benefits of antibiotic therapy. Limitations of the study include the non–population-based sample, the possibility that concern about infection was not always accompanied by a billing diagnosis or culture specimen, and lack of information about antibiotic prescribing at discharge.

These findings suggest a significant opportunity to improve patient safety, reduce the spread of resistance, and lower spending through greater adherence to guideline recommendations. We hope these results prompt hospital-based clinicians to examine local treatment patterns and attract the attention of professional societies and government agencies charged with promoting antimicrobial stewardship.

Corresponding Author: Peter K. Lindenauer, MD, MSc, Center for Quality of Care Research, Baystate Medical Center, 280 Chestnut St, Third Floor, Springfield, MA 01199 (peter.lindenauer@baystatehealth.org).

Published Online: July 25, 2016. doi:10.1001/jamainternmed.2016.4050.

Author Contributions: Dr Lindenauer had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of data analysis.

Study concept and design: Lindenauer, Stefan, Feemster, Carson, Au, Krishnan.

Acquisition, analysis, or interpretation of data: Lindenauer, Stefan, Feemster, Shieh, Carson, Au, Krishnan.

Drafting of the manuscript: Lindenauer.

Critical revision of the manuscript for important intellectual content: All authors.

Administrative, technical, or material support: We have all reviewed the final version of the manuscript and approve it for publication.

Conflict of Interest Disclosures: None reported.

Funding/Support: This study was supported by grants K01 HL114631 (Dr Stefan) and K23 HL111116 (Dr Feemster) from the National Heart, Lung, and Blood Institute of the National Institutes of Health and the Veterans Affairs Health Services Research and Development (Drs Feemster and Au).

Role of the Funder/Sponsor: The funding source had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The views expressed here are those of the authors and do not necessarily reflect the position or policy of the US Department of Veterans Affairs or the US government.