High-Risk Subgroups Have Little, if Any, Net Benefit from Antibiotics for Acute LRTI


Am Fam Physician. 2015 Oct 1;92(7):640-642.

Clinical Question

Are there subgroups of patients with acute lower respiratory tract infection (LRTI) who do not have clinically suspected pneumonia but who may benefit from antibiotics?

Bottom Line

Patients with acute LRTI and green sputum or cardiopulmonary comorbidities experience a slightly greater benefit with amoxicillin treatment. That outcome must be balanced against the harms of antibiotics on the individual and population level. (Level of Evidence = 1b –)


This is a secondary analysis of data from a large European randomized trial of the treatment of acute LRTI. These researchers recruited 2,061 adults with acute LRTI but no suspected pneumonia. The patients were randomized to receive 1 g of amoxicillin three times daily for seven days or matching placebo. Although U.S. physicians may criticize the choice of antibiotic, the prevalence of mycoplasma was extremely low in this cohort (0.2%), and there is good susceptibility of common respiratory pathogens to amoxicillin in Europe and the United Kingdom where this study took place. The current study identified subgroups of patients traditionally thought to be at increased risk of bacterial infection, namely those with lung disease, abnormal lung findings, a longer duration of illness, smokers, and those with fever or green sputum. For each subgroup, the authors looked at the effect of amoxicillin on symptom duration, severity, and new or worsening symptoms.

The overall results of the trial found a number needed to treat to prevent new or worsening symptoms of approximately 30, similar to the number needed to treat to harm for adverse events related to antibiotic use. Overall, the authors found minimal differences in outcomes for the identified high-risk subgroups. There was a somewhat greater reduction in duration of symptoms for patients with green sputum (approximately two days), and a greater reduction in symptom severity between days 2 and 4 for those with significant cardiopulmonary morbidities (approximately three more patients out of 10 who rated symptoms as mild rather than moderate). None of the subgroups saw a greater benefit in preventing a worsening of illness.

Study design: Randomized controlled trial (double-blinded)

Funding source: Government

Allocation: Concealed

Setting: Outpatient (primary care)

Reference: Moore M, Stuart B, Coenen S, et al.; GRACE consortium. Amoxicillin for acute lower respiratory tract infection in primary care: subgroup analysis of potential high-risk groups [published correction appears in Br J Gen Pract. 2014;64(620): 126]. Br J Gen Pract. 2014; 64( 619): e75– e80.

POEMs (patient-oriented evidence that matters) are provided by EssentialEvidence Plus, a point-of-care clinical decision support system published by Wiley-Blackwell. For more information, please see http://www.essentialevidenceplus.com. Copyright Wiley-Blackwell. Used with permission.

For definitions of levels of evidence used in POEMs, see http://www.essentialevidenceplus.com/product/ebm_loe.cfm?show=oxford.

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This series is coordinated by Sumi Sexton, MD, Associate Medical Editor.

A collection of POEMs published in AFP is available at https://www.aafp.org/afp/poems.



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