Objective. The purpose of this trial was to determine whether 20 days of antimicrobial treatment is more efficacious than 10 days of treatment for acute otitis media (AOM) in clearing middle ear effusion and preventing recurrences of AOM, and whether changing to a β-lactamase-stable antimicrobial agent after the initial 10-day treatment with amoxicillin for AOM is advantageous.
Methods. Children between 7 months and 12 years of age with AOM were randomly assigned to three treatment groups: (1) amoxicillin for days 1 through 10, then amoxicillin for days 11 through 20; (2) amoxicillin for days 1 through 10, then amoxicillin-clavulanate for days 11 through 20; and (3) amoxicillin for days 1 through 10, then a placebo for either amoxicillin or amoxicillin-clavulanate for days 11 through 20. Medication was dispensed in a double-blind manner. Children underwent tympanocentesis at entry and were re-examined on days 10, 20, 30, 60, and 90 after entry.
Results. Two hundred sixty-seven children entered the trial. At the 20-day visit, the percentages of children who were effusion free in the amoxicillin, amoxicillin-clavulanate, and placebo groups were 72.4%, 80.8%, and 52.5%, respectively. There was no statistically significant difference in the percentage of children who were effusion free between the amoxicillin and amoxicillin-clavulanate groups (95% confidence interval, -21.7, 4.9). Subsequent to the day 10 visit, the average proportions of time with middle ear effusion were not significantly different in the amoxicillin, amoxicillin-clavulanate, and placebo groups (0.29, 0.27, and 0.34, respectively), nor were there significant differences in the rates of recurrent episodes of AOM (0.56, 0.59, and 0.68, respectively). Regardless of treatment group, approximately 75% of children were effusion free at the time of their last visit.
Conclusions. More children were effusion free by the day 20 visit if given antimicrobial treatment for 20 days rather than for 10 days, but this advantage was present for only a short time; by the end of the 90-day study period, the treatment groups were comparable with regard to effusion status. Recurrence of AOM during the study period was not prevented by the additional 10 days of treatment. Routine use of an additional 10-day course of antimicrobial treatment is therefore not recommended if a child is symptom free after the initial 10 days of treatment for AOM.