Cochrane Database of Systematic ReviewsAlthough we included all measures of hearing assessment, the proportion of children who returned to normal hearing was our preferred method to assess hearing, due to challenges in interpreting the results of mean hearing thresholds.
Main resultsWe included 10 studies (1785 children). Many of the studies used concomitant interventions for all participants, including insertion of ventilation tubes or myringotomy. All included studies had at least some concerns regarding the risk of bias.We report results for our main outcome measures at the longest available follow-up. We did not identify any data on disease-specific quality of life for any of the comparisons. Further details of additional outcomes and time points are reported in the review.1) Adenoidectomy (with or without myringotomy) versus no treatment/watchful waiting (three studies) A er 12 months there was little di erence in the proportion of children whose hearing had returned to normal, but the evidence was very uncertain (adenoidectomy 68%, no treatment 70%; risk ratio (RR) 0.97, 95% confidence interval (CI) 0.65 to 1.46; number needed to treat to benefit (NNTB) 50; 1 study, 42 participants). There is a risk of haemorrhage from adenoidectomy, but the absolute risk appears small (1/251 receiving adenoidectomy compared to 0/229, Peto odds ratio (OR) 6.77, 95% CI 0.13 to 342.54; 1 study, 480 participants; moderate certainty evidence). The risk of persistent OME may be slightly lower a er two years in those receiving adenoidectomy (65% versus 73%), but again the di erence was small (RR 0.90, 95% CI 0.81 to 1.00; NNTB 13; 3 studies, 354 participants; very low-certainty evidence).
2) Adenoidectomy (with or without myringotomy) versus non-surgical treatmentNo studies were identified for this comparison.
3) Adenoidectomy and bilateral ventilation tubes versus bilateral ventilation tubes (four studies)There was a slight increase in the proportion of ears with a return to normal hearing a er six to nine months (57% adenoidectomy versus 42% without, RR 1.36, 95% CI 0.98 to 1.89; NNTB 7; 1 study, 127 participants (213 ears); very low-certainty evidence). Adenoidectomy may give an increased risk of haemorrhage, but the absolute risk appears small, and the evidence was uncertain (2/416 with adenoidectomy compared to 0/375 in the control group, Peto OR 6.68, 95% CI 0.42 to 107.18; 2 studies, 791 participants). The risk of persistent OME was similar for both groups (82% adenoidectomy and ventilation tubes compared to 85% ventilation tubes alone, RR 0.96, 95% CI 0.86 to 1.07; very low-certainty evidence).
4) Adenoidectomy and unilateral ventilation tube versus unilateral ventilation tube (two studies)Slightly more children returned to normal hearing a er adenoidectomy, but the confidence intervals were wide (57% versus 46%, RR 1.24, 95% CI 0.79 to 1.96; NNTB 9; 1 study, 72 participants; very low-certainty evidence). Fewer children may have persistent OME a er 12 months, but again the confidence intervals were wide (27.2% compared to...