Clinical Health Updates

Antibiotics for URIs reduce complications (but not enough to matter)

Clinical Question:
Does antibiotic treatment of common respiratory infections decrease the risk of serious complications?

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

Petersen I, Johnson AM, Islam A, Duckworth G, Livermore DM, Hayward AC. Protective effect of antibiotics against serious complications of common respiratory tract infections: retrospective cohort study with the UK General Practice Research Database. BMJ 2007;335(76-27):982-987.

Study Design:
Cohort (prospective)

The authors determined the extent to which antibiotics reduce the risk of serious complications after common respiratory tract infections. They did a Retrospective cohort study. They used UK primary care practices contributing to the general practice research database 3.36 million episodes of respiratory tract infection. The investigators study the risk of serious complications in treated and untreated patients in the month after diagnosis: mastoiditis after otitis media, quinsy after sore throat, and pneumonia after upper respiratory tract infection and chest infection. Number of patients needed to treat to prevent one complication. Serious complications were rare after upper respiratory tract infections, sore throat, and otitis media, and the number needed to treat was over 4000. The risk of pneumonia after chest infection was high, particularly in elderly people, and was substantially reduced by antibiotic use, with a number needed to treat of 39 for those aged > or =65 and 96-119 in younger age groups.

Pneumonia in patients aged 16 years to 64 years decreased from 6.73 to 5.4 per 10,000 URIs with the use of antibiotics. Though statistically significant, 4407 patients (of all ages) have to be treated with an antibiotic to prevent 1 episode of pneumonia (number needed to treat (NNT) = 4407 for all ages; NNTs were not provided for individual age groups). Results were similar for peritonsillar abscess following sore throat and mastoiditis associated with ear infection: antibiotics decreased complications but had NNTs greater than 4000. The only exception was the incidence of pneumonia after bronchitis: The NNTs varied by age from 119 in patients aged 16 years to 64 years to 39 for patients older than 65 years.