US study finds antibiotics don't reduce duration, severity of cough

Man coughing at doctor's office

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New research conducted at US primary and urgent care sites shows that antibiotics didn't provide any benefit for patients with a cough caused by an acute lower respiratory tract infection (LRTI).

In fact, the findings, published yesterday in the Journal of General Internal Medicine, show that receipt of an antibiotic was associated with a small but significant increase in the duration of cough overall compared with those who didn't receive an antibiotic. Even for those patients with a confirmed bacterial infection, the time until illness resolution was the same whether or not the patients received an antibiotic.

Patients who received an antibiotic also had a higher overall disease severity over the entire course of their illness compared with those who didn't.

The study authors say the results of the Enhancing Antibiotic Stewardship in Primary Care (EAST-PC) study, which is the largest observational study to date on LRTIs in US primary and urgent care settings, are yet another indication that clinicians should be more prudent about using antibiotics for LRTIs.

No measurable impact on cough duration, severity

To assess the association between antibiotic prescribing and the duration and severity of acute cough—the most common illness-related reason that brings people to doctor's offices and urgent care clinics—researchers from Georgetown University, the University of Georgia, and the University of Wisconsin collected data on adults ages 18 to 75 who reported a cough at primary and urgent care clinics in Washington, D.C.; Athens, Georgia; and Madison, Wisconsin.

From June 2019 to April 2023, the researchers collected data on patient demographics and the presence and severity of their respiratory symptoms, tested patient swab samples for 48 viral and bacterial respiratory pathogens using polymerase chain reaction (PCR) tests, and recorded any medications prescribed at the index visit. The severity of cough was recorded at baseline and on days 3, 7, 14, 21, and 28 via text linked to an online survey.

A total of 718 patients (mean age, 39 years; 65.3% female; 78.1% White) with acute LRTI were enrolled in the study. Seventy-five percent of patients had a moderately bad or worse cough. The mean duration of cough was 5.1 days prior to presentation. 

Overall, 29.0% of patients received at least one antibiotic, while 7.1% received an antiviral agent. The antibiotics most commonly prescribed were amoxicillin-clavulanate, azithromycin, doxycycline, and amoxicillin. Antibiotic prescribing occurred in 68.9% of visits in Athens, 28.6% of visits in Madison, and 20.6% in Washington, D.C. 

The patients who received antibiotics presented to the clinic further along in their illness compared with those who didn't (6.3 days vs 4.7 days) and had higher Bronchitis Severity Scores (mean 7.6 vs 6.8 points). Patients who received an antibiotic were also significantly more likely than those who didn't to receive a systemic corticosteroid (31.9% vs 4.5%) and an albuterol inhaler (22.7% vs 7.6%).

While patients expected that their duration of cough would be shortened by 4 days if they received an antibiotic, the results showed that those who were prescribed an antibiotic had a cough for a day and a half longer than those who weren't prescribed an antibiotic (17.5 vs 15.9 days). The researchers believe that this is probably because the patients more likely to receive an antibiotic had a longer illness prior to the index visit.

But still, for the 40 patients who had a bacterial pathogen detected on PCR tests, the duration of cough was the same (17.3 vs 17.4 days) whether or not an antibiotic was prescribed.

"Even when one had a bacterial infection, antibiotics didn't do much more [for them]," lead study author Daniel Merenstein, MD, a professor of family medicine at Georgetown University School of Medicine, said in an email. 

Unsurprisingly, cough duration was similar among those who had a viral infection regardless of whether they received an antibiotic (14.5 days with antibiotics vs 15.4 days without). However, among those who had a viral and bacterial infection, receiving an antibiotic was associated with a significantly longer time to cough resolution (21.2 vs 15.8 days). 

Even when one had a bacterial infection, antibiotics didn't do much more [for them].

Univariate and multivariate analysis found that the use of antibiotics was not independently associated with the duration or severity of cough. The one outcome where antibiotics appeared to make a difference was in the likelihood of a follow-up visit, which was reduced by almost half in those who received an antibiotic (14.1% vs 8.2%; adjusted odds ratio [aOR], 0.47; 95% confidence interval [CI], 0.26 to 0.84). 

"It is likely that having received an antibiotic at the index visit removed an important patient motivation for a follow-up visit (e.g., to obtain an antibiotic)," the study authors wrote.

Implications for clinical practice

The findings add to what is known about a familiar topic in antibiotic stewardship. Several studies in recent years have documented the excessive and inappropriate use of antibiotics for respiratory infections in outpatient settings, which Merenstein notes is where 50% of medical care occurs. A 2016 study led by researchers with the US Centers for Disease Control and Prevention estimated that roughly half of antibiotic prescriptions written for acute respiratory conditions in US ambulatory care settings were unnecessary.

"Physicians know, but probably overestimate, the percentage of lower-tract infections that are bacterial; they also likely overestimate their ability to distinguish viral from bacterial infections," study co-author Mark H. Ebell, MD, a professor in the College of Public Health at the University of Georgia, said in a press release.

But the providers in the EAST-PC study appear to have been more careful about antibiotic prescribing for LRTIs, as the documented rate of prescribing was lower than previous studies have found. Merenstein said that may be because the clinicians in the study knew their prescriptions were being recorded. In addition, they had PCR test results to inform their decisions.

"I think it is fair to say then that when patients [in the study] got antibiotics, they had a higher likelihood of success," Merenstein said. "But even in this select group we didn't see any benefit."

That suggests antibiotic prescribing for LRTIs could be reduced even more. Merenstein and his colleagues say that one thing clinicians could do to avoid requests for antibiotics is to clarify for patients how long acute LRTI symptoms typically last. They also call for further research to determine if there is a limited role for antibiotics in certain patients with a cough.

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