Drugs and Antibiotics

News Author: Laurie Barclay, MD, CME Author: Charles Vega, MD
Complete author affiliations and disclosures, and other CME information, are available at the end of this activity.

October 19, 2007 – Although antibiotics are not justified to reduce the risk for serious complications for upper respiratory tract infection, sore throat, or otitis media, they do substantially decrease the risk for pneumonia after chest infection, particularly in elderly people in whom the risk is greatest, according to the results of a retrospective cohort study reported in the October 18 Online First issue of the BMJ.

“Most antibiotic prescribing is in primary care, and most of it is for respiratory tract infections,” write I. Petersen, from University College London, United Kingdom, and colleagues. “Clinical guidelines advise against the routine use of antibiotics in patients with upper respiratory tract infection, sore throat, and otitis media. Guidelines divide chest infection into acute bronchitis, for which antibiotics are not recommended, and pneumonia, for which they are recommended.”

Using a general practice research database of UK primary care practices, the authors evaluated outcomes in 3.36 million episodes of respiratory tract infection. Primary endpoints were risk for serious complications in treated and untreated patients in the month following diagnosis (mastoiditis after otitis media, quinsy after sore throat, and pneumonia after upper respiratory tract infection and chest infection). The number of patients needed to treat to prevent 1 complication was calculated.

Following upper respiratory tract infections, sore throat, and otitis media, serious complications were rare, and the number needed to treat was more than 4000.

However, the risk for pneumonia after chest infection was high, especially in the elderly. This risk was substantially reduced by antibiotic use, with a number needed to treat of 39 for individuals 65 years or older and 96 to 119 in younger age groups. The risks for pneumonia following chest infection and the number of antibiotic courses needed to prevent 1 case of pneumonia were not significantly different in smokers or in patients with chronic respiratory or cardiac disease.

“Antibiotics are not justified to reduce the risk of serious complications for upper respiratory tract infection, sore throat, or otitis media,” the authors write.” Antibiotics substantially reduce the risk of pneumonia after chest infection, particularly in elderly people in whom the risk is highest.”

Study limitations include nonrandomized design, possible underestimation of the protective effect of antibiotics, reliance on codes that general practitioners have assigned to conditions, possible misclassification of chest infection and pneumonia, and possible biases leading to underestimation of the risk for pneumonia.

“It is now unlikely that randomised controlled trials that are sufficiently large to accurately measure the protective effect of antibiotics on serious complications of common respiratory tract infection will ever be conducted,” the authors conclude. “For upper respiratory tract infection, sore throat, and otitis media, research should focus on effective interventions to reduce prescribing. For chest infection, research should focus on developing clinical algorithms and diagnostic technology that can be easily applied in primary care to enable confident distinction between acute bronchitis and early pneumonia and to identify those who are most likely to develop pneumonia.”

The Department of Health funded this study. Two authors have disclosed various financial relationships with GlaxoSmithKline and/or other pharmaceutical companies.

In an accompanying editorial, Samuel Coenen, MD, and Herman Goossens, MD, from the University of Antwerp in Belgium, note that most infections can be managed by watchful waiting. They point out a major confounding factor in this study, namely that sicker patients and those more likely to have adverse outcomes were offered antibiotics more often.

“The available evidence does not provide clinicians with the guidance they need to prescribe antibiotics effectively for common infections in primary care, except maybe for acute otitis media,” Drs. Coenen and Goossens write. “For lower respiratory tract infections in particular, clinicians cannot be confident about identifying who will benefit from antibiotics and who will not. GRACE (genomics to combat resistance against antibiotics in community acquired lower respiratory tract infections in Europe; www.grace-lrti.org), a network funded by the European Commission, is currently undertaking research across Europe to provide answers to these questions.”

Drs. Coenen and Goossens are members of the ESAC and the GRACE management teams.

BMJ. Published online October 18, 2007.

Learning Objectives for This Educational Activity
Upon completion of this activity, participants will be able to:

Compare different strategies of antibiotic prescribing for acute bronchitis.
Identify the prevalence of complications of common respiratory tract infections and the role of antibiotics in prevention of these complications.
Clinical Context
Acute bronchitis can present a diagnostic and therapeutic challenge to the clinician. Generally, guidelines suggest withholding antibiotics from patients with acute bronchitis, but these patients are at risk of developing pneumonia. A study by Little and colleagues of 807 patients presenting with acute bronchitis, which was published in the June 22, 2005, issue of the Journal of the American Medical Association, compared treatment strategies of no antibiotic prescription, a delayed prescription for antibiotics if symptoms did not improve, and immediate antibiotics. Antibiotics were ineffective in reducing the duration of cough. Compared with patients receiving antibiotics immediately, subjects in the other randomized groups were less satisfied with care but also less convinced of the effectiveness of antibiotics for this condition. Patients receiving antibiotics immediately were also less likely to return to the clinic in the following month.

The current study examines how antibiotic prescriptions affect serious complications related to common upper respiratory tract infections.

Study Highlights
Data was drawn from 162 general practices in the United Kingdom.
Billing data was used to investigate patients diagnosed with chest infection, upper respiratory tract infection, sore throat, and acute otitis media. Researchers were able to discern which of these patients received antibiotics. Patients with a complication of infection at baseline were excluded from analysis.
The main study outcome was the prevalence of complications of infection as related to the prescription of antibiotics. These complications included mastoiditis for otitis media, quinsy for sore throat, and pneumonia for chest infection or upper respiratory tract infection.
Researchers found 1,081,000 cases of upper respiratory tract infection, 1,065,088 cases of sore throat, 749,389 cases of chest infection, and 459,876 cases of otitis media.
The overall rate of complications of all infections was low, particularly for quinsy, mastoiditis, and pneumonia after upper respiratory tract infection. The number of patients needed to treat with antibiotics to prevent 1 of these complications exceeded 4000, and this result did not vary significantly by patient age.
There were too few cases of acute rheumatic fever or acute glomerulonephritis following sore throat to determine whether antibiotics were effective in preventing these outcomes.
The risk for pneumonia following chest infection was more significant, particularly among patients at age 65 years or older. Rates of a diagnosis of pneumonia in the 30 days following chest infection among these older adults were 4% among patients who did not receive antibiotics and 1.5% among patients who received antibiotics.
The number of patients with chest infection needed to treat with an antibiotic to prevent 1 additional case of pneumonia was 39 among subjects at age 65 years or older and 96 to 119 among younger patients.
Analyses including smoking status and the presence of chronic respiratory disease failed to alter the study’s main findings.
Pearls for Practice
A previous study found no difference in the duration of cough in cases of acute bronchitis with treatment strategies of no antibiotics, delayed antibiotics, and immediate antibiotics. Compared with other groups, immediate antibiotics improved patient satisfaction and the rate of return to clinic, and patients in the delayed or no antibiotic groups were less convinced of the efficacy of antibiotics.
The current study suggests that quinsy following sore throat, mastoiditis following otitis media, and pneumonia following upper respiratory tract infection are rare, and prescribing antibiotics to prevent these complications is not feasible. However, pneumonia following chest infection is more common, particularly among older adults, and antibiotics may be effective in preventing this complication.

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