Cochrane review on Antibiotics for Acute Otitis Media (2002 update) and Cates plots

Have the results changed?

Yes and No! The overall difference made by antibiotics remains very similar in terms of the Odds Ratio of being in pain at 2 to 7 days; this is still 0.6 and has not been changed much by the data from the new trial in children under 2 years of age (1). The Odds Ratio from this study is also in keeping with the overall effect at 0.55 but what is strikingly different is the proportion of children in this group who are still in pain on placebo treatment. For all of the other studies combined the proportion still in pain at 2 to 7 days is 14% (145/1005) whilst in the Damoiseaux study the figure is 70% (89/123). When all the studies are combined together the proportion in pain is 21% (234/1128) and combined with the pooled Odds Ratio of 0.6 this means that seven out of every 100 treated will see a benefit, and leads to an overall NNT of 14 as was shown in an article in Prescriber on putting evidence into practice. This overall Cates plot is shown below, but it conceals differences between the Damoiseaux study and the other trials.

If we take the pooled Odds Ratio of 0.6 as the best measure of effect and enter this in Visual Rx  with the Control event rate of 14% (from all the other trials) this will give an NNT of 19, as five (yellow faces) will benefit for every 100 treated. This is very similar to the original review and is shown in the Figure below:

In contrast the same Odds Ratio of 0.6 applied to the 70% Control Event Rate in the Damoiseaux trial in children under 2 there will be 12 (yellow faces) who benefit for every 100 treated as shown in the Cates plot below, and this will give an NNT of 9 .

This would suggest that in children similar to those studied by Damoiseaux in the younger age group, there is more benefit in using antibiotics than in those from the other trials. Perhaps the age of the child should be taken into consideration, as well as the level of fever and systemic illness (2) in making a decision about deferring antibiotics in children with ear infections.

Please also see the paper on discharging ears to help decide which children may benefit most from antibiotics for their ear infections.




  1. Damoiseaux RAMJ, van Balen FAM, Hoes AW, Verheij TJM, de Melker RA. Primary care based randomised, double blind trial of amoxicillin versus placebo for acute otitis media in children aged under 2 years. BMJ 2000;320(7231):350-354
  2. Little P, Gould C, Moore M, Warner G, Dunleavey J, Williamson I, et al. Predictors of poor outcome and benefits from antibiotics in children with acute otitis media: pragmatic randomised trial. BMJ 2002;325(7354):22-8