The antibiotic amoxicillin fares no better at reducing symptoms in patients with lower-respiratory tract infections (LRTI) than a placebo drug, indicate data from a dozen European countries.
The randomized controlled trial results show no difference in the duration of symptoms or average symptom severity for patients who received antibiotics compared with their placebo-treated peers.
Therefore, once pneumonia has been ruled out, patients with LRTIs should not be prescribed antibiotics, suggest the researchers in The Lancet Infectious Diseases.
"Indeed, using amoxicillin to treat respiratory infections in patients not suspected of having pneumonia is not likely to help and could be harmful," said study author Paul Little (University of Southampton, UK) in a press statement.
"Overuse of antibiotics, which is dominated by primary care prescribing, particularly when they are ineffective, can lead to side effects such as diarrhoea, rash, vomiting and the development of resistance," he added.
For the study, 3108 patients were recruited and randomly assigned to receive either amoxicillin (1 g daily, n=1038) or placebo, for 7 days.
Participants completed a symptom diary for the duration of their illness (up to 28 days), scoring symptoms such as severity of cough, phlegm, shortness of breath, and chest pain out of 6, where 6 equals "as bad as it could be."
The researchers used the completed diaries to categorize the duration and severity of symptoms as "moderately bad" or "worse" than at initial presentation, and overall, 17.6% of the cohort had new or worsening symptoms during the 28-day study period.
Significantly fewer individuals in the amoxicillin group experienced new or worsening symptoms than their placebo-treated peers, note the authors.
Symptoms rated "moderately bad" or "worse" lasted marginally, but not significantly, longer in the placebo than the amoxicillin group, at 7 versus 6 days, indicating no significant difference in symptom severity between treatment groups.
Indeed, the hazard ratio for longer duration of symptoms was 1.06 and the odds ratio for worsening symptoms was 0.80, report Little et al.
When the team excluded groups of patients with potentially confounding characteristics from the analysis, including those with asthma, chronic obstructive pulmonary disease, and those aged 60 years or over (n=595), the results were unchanged.
This suggests that the findings "can probably be generalised to most patients with clinically defined acute lower-respiratory-tract infection in primary care," conclude the researchers.
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