A Cochrane review ¹ included 14 studies with a total of 2,712 children. Adenoidectomy in combination with a unilateral tympanostomy tube had a beneficial effect on the resolution of otitis media with effusion (risk difference, RD 22%, 95% CI 12% to 32% and RD 29%, 95% CI 19% to 39% for the non-operated ear at six and 12 months, respectively; 3 studies, n=298) and a very small (< 5 dB) effect on hearing, compared to a unilateral tympanostomy tube only. The results of studies of adenoidectomy with or without myringotomy versus non-surgical treatment or myringotomy only, and those of adenoidectomy in combination with bilateral tympanostomy tubes versus bilateral tympanostomy tubes only, also showed a small beneficial effect of adenoidectomy on the resolution of the effusion. These results could not be pooled due to large heterogeneity of the trials. Regarding acute otitis media, the results of none of the trials including this outcome indicate a significant beneficial effect of adenoidectomy. The trials were too heterogeneous to pool in a meta-analysis. The effects of adenoidectomy on changes of the tympanic membrane or cholesteatoma were not reported in any of the included studies.

An individual patient data meta-analysis ² included 10 trials. The primary outcome was failure at 12 months, defined by a set of persisting symptoms and signs. In the prognostic analysis 56% of those children referred for adenoidectomy (but randomised to the non-surgical group) failed to improve (38% of the children with recurrent AOM and 89% of the children with persistent OME). Children who had adenoidectomy had a greater chance of clinical improvement. The size of that effect was small but persisted for at least 2 years. Two subgroups of children most likely to benefit from adenoidectomy were (1) children aged < 2 years with recurrent AOM – 16% of those who had adenoidectomy failed at 12 months whereas 27% of those who did not have adenoidectomy failed [rate difference (RD) 12%, 95% Cl 6% to 18%; NNT = 9]; (2) children aged ≥ 4 years with persistent OME – 51% of those who had adenoidectomy failed at 12 months whereas 70% of those who did not have adenoidectomy failed (RD 19%, 95% Cl 12% to 26%; NNT = 6). No significant benefit of adenoidectomy was found in children aged ≥ 2 years with recurrent AOM and children aged < 4 years with persistent OME.

Comment: The quality of evidence is downgraded by study quality (significant loss to follow up in most studies) and by inconsistency (heterogeneity in study populations and outcomes).