Antibiotics justified to prevent pneumonia after chest infection, but not to prevent other serious complications after respiratory tract infection

In a retrospective cohort study of 162 primary care practices in the United Kingdom, the use of antibiotics was demonstrated to be effective in preventing serious complications following upper respiratory tract infection (URTI), sore throat, or otitis media; however, the authors stated that the number needed to treat (NNT) to prevent 1 such complication is too high to justify prescription of the drugs for this purpose.

Key Points

In a retrospective cohort study of 162 primary care practices in the United Kingdom, the use of antibiotics was demonstrated to be effective in preventing serious complications following upper respiratory tract infection (URTI), sore throat, or otitis media; however, the authors stated that the number needed to treat (NNT) to prevent 1 such complication is too high to justify prescription of the drugs for this purpose. According to the authors, the use of antibiotics to prevent pneumonia in patients with chest infections is justified, especially among patients aged ≥65 years.

The study, published in the British Medical Journal, included data from the UK General Practice Research Database, collected from July 1, 1991, to June 30, 2001. Nearly 3.4 million patients diagnosed with URTI (n=1,081,000), sore throat (n=1,065,088), otitis media (n=459,876), or chest infection (n=749,389) were included in the analysis.

The researchers assessed the risk of the development of serious complications in the month after diagnosis and compared this risk between patients treated with antibiotics and those not treated with antibiotics. The complications included in the assessment were mastoiditis in patients with otitis media, quinsy in patients with sore throat, and pneumonia in patients with URTI or chest infection. ORs for the potential protective effect of antibiotics were calculated using logistic regression, with adjustments for age, sex, and social deprivation. The NNT was calculated if the use of antibiotics was associated with a significant protective effect.

Antibiotic use was associated with significant reductions in the risk of the development of pneumonia in patients with chest infection compared with patients not treated with antibiotics. The risk reduction and NNT varied greatly by age, with the greatest benefit demonstrated among patients aged ≥65 years (adjusted OR=0.35; 95% CI, 0.33–0.38; P<.001; NNT=39. Antibiotic use was also associated with a significant reduction in the risk of pneumonia in other age groups (patients aged 16–64 years, adjusted OR=0.27; 95 % CI, 0.23–0.32; P<.001; NNT=119; patients aged 5–15 years, adjusted OR=0.18; 95% CI, 0.13–0.24; P<.001; NNT=96; patients aged 0–4 years, adjusted OR=0.22; 95% CI, 0.17–0.27; P<.001; NNT=101).

According to the authors, "General practitioners already prescribe antibiotics to nearly all patients with chest infection but are often criticized for doing so. We have shown that antibiotic prescribing to reduce the risk of pneumonia after chest infection is justifiable, particularly in elderly patients."

SOURCE

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;335:982.