The quality of evidence is downgraded by study limitations (unclear allocation concealment and lack of blinding).
A Cochrane review included 5 studies with a total of 805 children aged 0 to 10 years with recurrent acute otitis media (AOM). None of the studies performed adenoidectomy as background therapy, and the effectiveness of grommets as add-on therapy to adenoidectomy could not be assessed. All studies were conducted prior to the introduction of pneumococcal vaccination in the countries' national immunization programmes. None of the studies reported the effect of grommets on the severity of AOM recurrences or antibiotic consumption.
Grommets versus active monitoring: Children receiving grommets were more likely to have no AOM recurrences at 6 months (46% versus 5%; RR 9.49, 95% CI 2.38 to 37.80; 1 study, n=95, NNTB 3) and at 12 months (48% versus 34%; RR 1.41, 95% CI 1.00 to 1.99, 1 study, n=200, NNTB 8) than those managed by active monitoring. Number of AOM recurrences at 6 months (mean number of AOM recurrences per child: 0.67 versus 2.17, MD -1.50, 95% CI -1.99 to -1.01; 1 study, n=95) and at 12 months (one-year AOM incidence rate: 1.15 versus 1.70, incidence rate difference -0.55, 95% -0.17 to -0.93; 1 study, n=200) were lower in the grommets group compared to active monitoring. One study reported no persistent tympanic membrane perforations among 54 children receiving grommets.
Grommets versus placebo medication: Grommets were more effective than placebo medication in terms of proportion of children who had no AOM recurrence at 6 months (55% versus 15%; RR 3.64, 95% CI 1.20 to 11.04, 1 study, n=42, NNTB 3) and in the number of AOM recurrences at 6 months (mean number of AOM recurrences per child: 0.86 versus 2.0, MD -1.14, 95% CI -2.06 to -0.22; 1 study, n=42). One study reported persistent tympanic membrane perforations in 3 of 76 children (4%) receiving grommets.
Grommets versus antibiotic prophylaxis: Proportion of children who had no AOM recurrence at 6 months (60% versus 35%; RR 1.68, 95% CI 1.07 to 2.65, 2 studies, n=96, NNTB 5) was higher in the grommets group compared to antibiotic prophylaxis. There were no differences in the number of AOM recurrences at 6 months (mean number of AOM recurrences per child: 0.86 versus 1.38, MD -0.52, 95% CI -1.37 to 0.33; 1 study, n=43).
Widespread use of pneumococcal vaccination has changed the bacteriology and epidemiology of AOM, and how this might impact the results of prior studies is unknown. Grommets may reduce the severity and pain of AOM recurrences and allow for topical rather than oral antibiotic treatment.