A Cochrane review [Abstract] 1 included 10 studies with a total of 1 728 subjects. Grommets were mainly beneficial in the first 6 months by which time natural resolution lead to improved hearing in the non-surgically treated children also. Only one high quality trial that randomised children (n=211) reported results at 3 months; the mean hearing level was 12 dB better (95% CI 10 to 14 dB) in those treated with grommets as compared to the controls. Meta-analyses of 3 high quality trials (n=523) showed a benefit of 4 dB (95% CI 2 to 6 dB) at 6 to 9 months. At 12 and 18 months follow up no differences in mean hearing levels were found. Data from 3 trials that randomised ears (n=230 ears) showed similar effects to the trials that randomised children. At 4 to 6 months mean hearing level was 10 dB better in the grommet ear (95% CI 5 to 16 dB), and at 7 to 12 months and 18 to 24 months was 6 dB (95% CI 2 to 10 dB) and 5 dB (95% CI 3 to 8 dB) better. No effect was found on language or speech development or for behaviour, cognitive or quality of life outcomes.
Tympanosclerosis was seen in about a third of ears that received grommets. Otorrhoea was common in infants, but in older children (3 to 7 years) occurred in < 2% of grommet ears over two years of follow up.
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