Most common infections don't need antibiotics

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BMJ

A new study by researchers in the UCL Centre for Infectious Disease Epidemiology (CIDE) has shown that antibiotics are not justified to reduce the risk of complications after upper respiratory tract infection, sore throat, or ear infection.

The paper, published by the British Medical Journal, does provide evidence that antibiotics do substantially cut the risk of pneumonia after chest infection, particularly in elderly people.

Most antibiotics are prescribed by GPs, and mostly for common respiratory tract infections, such as tonsillitis, sinusitis and the common cold. Recommendations not to prescribe antibiotics for these conditions are based on concerns about the development of resistance and evidence of minimal benefit for the patient. The continued high rate of antibiotic prescription may be put down to patient expectation and fear of complications arising from the infection.

The research team, led by Dr Andrew Hayward, set out to find whether there was a higher rate of complications resulting in patients who had not been prescribed antibiotics, compared to those who had taken them. They examined 3.36 million cases of respiratory tract infection to find out how many had suffered from serious complications.

The data was taken from 162 practices on the UK General Practice Research Database from 1991 to 2001. The team recorded how many cases developed serious complications of common respiratory tract infections comparing those
who were prescribed antibiotics and those who were not.

Risk of serious complications in the month after diagnosis were recorded: mastoiditis - infection of the mastoid bone of the skull - after ear infection, quinsy - an abscess at the back of the throat - after sore throat, and pneumonia after upper respiratory tract infection and chest infection.

Serious complications were rare after upper respiratory tract infections, sore throat, and ear infection. Antibiotics reduced the risk, but only one complication was prevented per 4,000 courses.

In contrast, the risk of pneumonia after chest infection was high, particularly in elderly people, and was substantially reduced by antibiotic use. Without an antibiotic prescription, four per cent of patients aged 65 or over were diagnosed with pneumonia in the month after diagnosis, compared to 1.5 per cent of those who were treated with an antibiotic.

The risks were not appreciably different in smokers, those with chronic respiratory disease, or those with cardiac disease.

Dr Hayward concluded: "General practitioners should not base their prescribing for sore throat, ear infection, or upper respiratory tract infections on a fear of serious complications. However, antibiotic prescribing to reduce the risk of pneumonia after chest infection is justifiable, particularly in elderly patients in whom the risk is highest."

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Image: Antibiotics were found to be effective only for preventing pneumonia in the over 65's