Antibiotic effectiveness for children with lower respiratory infections: prospective cohort and trial

Background: Antibiotics are commonly prescribed for children with chest infections, but there is little randomised evidence, and trials commonly recruit selected populations which undermines their applicability. Aim: To document the effectiveness of antibiotics for chest infections in children. Design: Prospective cohort study with nested trial. Setting Primary care Methods: Children aged one to twelve presenting with uncomplicated lower respiratory tract infections were included in the cohort. Children were either randomised to receive Amoxicillin 50mg/kg/day/7 days or placebo, or participated in a parallel observational study, where propensity scores controlled for confounding by indication. Outcomes: duration of symptoms rated moderately bad or worse (primary outcome); illness progression requiring hospital assessment. Results: 758 children participated (432 trial, 326 observational), and children were more unwell than in previous cohorts (more sputum, fever, shortness of breath). Children had been unwell for a median of 6 days, and symptoms rated moderately bad or worse lasted another 6 days when no antibiotics were given. With antibiotics there was a non significant reduction of approximately a day in duration of symptoms rated moderately bad or worse for the whole cohort (Hazard ratio 1.16 (0.95, 1.41), similar to the trial alone ( HR1.13, 95% CIs 0.90,1.43). ). The effect of antibiotic treatment on secondary outcomes was also non-significant. Conclusion: Antibiotics for uncomplicated chest infections, even in a sample of more unwell children, are unlikely to be clinically very effective.