Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. In this retrospective cohort study looking at patients admitted with asthma exacerbations and treated with corticosteroids, antibiotic administration within the first two days, given for at least two days, was associated with longer length of stay in hospital and higher health care expenditures.

2. There was no concurrent improvement in clinical outcomes or reductions in clinical deterioration.

Evidence Rating Level: 2 (Good)

Study Rundown:

Asthma is one of the most common respiratory conditions seen across North America in both primary care and inpatient settings. Despite clear and concordant guidelines, the existing literature demonstrates poor adherence by health care practitioners. One specific area of poor adherence is routine antibiotic administration, which is not currently recommended. This retrospective cohort study of almost 20,000 patients admitted for asthma exacerbations and treated with corticosteroids in the United States found that early antibiotic administration was linked with longer length of stay in hospital, higher costs, and a trend towards higher rates of antibiotic associated diarrhea. There was no difference in in-hospital mortality, transfer to ICU, mechanical ventilation, or re-admission for asthma exacerbation in 30 days. Early antibiotic use was noted in almost half of the cohort.

The large sample size, limited exclusion criteria, and thorough statistical analyses as well as sensitivity analyses all support this study’s conclusion. Given the retrospective nature of the study, there are likely confounders that could not be adjusted.

In-Depth [retrospective cohort]:

This was a large, retrospective cohort study of 19,811 adults hospitalized for asthma exacerbations and treated with corticosteroids across 543 acute care facilities in the United States. Recruitment occurred between January 2015 and December 2016. Inclusion criteria included age of 18 or older and treatment with oral or IV corticosteroids (minimum 20 mg/day of prednisone equivalent). Exclusion criteria included any separate indication for antibiotic therapy, patients with blood or sputum cultures taken on admission, or patients transferred from another acute care facility (to avoid confounding from antibiotics given there). The exposure of interest was antibiotic therapy during the first two days of admission, maintained for at least 2 days total. The primary outcome was hospital length of stay, and the main secondary outcome was a composite measure called treatment failure, which comprised of in-hospital mortality, initiation of mechanical ventilation, transfer to ICU, or readmission with asthma exacerbation within 30 days of discharge. Other outcomes of interest included hospital cost, allergic reactions, and antibiotic associated diarrhea.

Of the 19,811 patients included, 8,788 (44.4%) received early antibiotic therapy as described above. There was no difference in treatment failure for patients treated with or without antibiotics (5.5% vs 5.7%, p=0.58). Length of stay was higher for patients treated with antibiotics (median 4 days, interquartile range 3-5 days) versus without antibiotics (median 3 days, interquartile range 2-4 days) (p<0.001). Patients treated with antibiotics had higher rates of antibiotic associated diarrhea, however this was not statistically significant (1.4% vs 1.1%) (adjusted OR 1.34, 95% CI 0.99 – 1.83). Treatment with antibiotics was also linked with higher hospitalization costs (median $4776 vs $3641).

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