The Pharmaceutical Journal
Vol 279 No 7475 p463
27 October 2007

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Chest infection complications reduced by antibiotics

Prescribing antibiotics following a chest infection substantially reduces the risk of pneumonia, particularly in patients over 65 years old, according to research published online (BMJ Online First, 18 October 2007).

However, in general, prescribing antibiotics to reduce the risk of serious complications after upper respiratory infection, sore throat or otitis media is not justified, it adds.

Although guidelines advise against routine prescribing of antibiotics for upper respiratory tract infection, sore throat or otitis media, antibiotics are often prescribed for patients with these conditions, researchers from University College London and the Health Protection Agency explain.

The researchers analysed 3.36 million episodes of respiratory tract infection recorded between 1991 and 2001 on the UK General Practice Research Database. They calculated and compared the risk of serious complications in treated and untreated patients in the month following diagnosis.

The researchers found that serious complications — mastoiditis after otitis media, quinsy after sore throat and pneumonia after upper respiratory tract infection — were rare, with a number needed to treat of over 4,000.

However, they identified a high risk of pneumonia following chest infection, which was substantially reduced by treatment with antibiotics (the number needed to treat was 39 in those aged over 65 years and over and between 96 and 119 in those under 65 years).

Smoking and chronic respiratory disease did not affect the risk of complications or the protective effect of antibiotics, say the researchers.

The authors of an accompanying editorial highlight a major confounding factor in that sicker patients and those more likely to have adverse outcomes were offered antibiotics more often, potentially leading to an underestimation of the protective effect of antibiotics.

However, they acknowledge that, although randomisation would eliminate this bias, randomised controlled trials generally lack the power to study rare events.