Interventions for the prevention of postoperative ear discharge after insertion of ventilation tubes (grommets) in children

The insertion of a grommet is a common surgical procedure performed in children. Ear discharge (otorrhoea) is often complained of after the procedure. A wide range of treatments are used to prevent the discharge, but the evidence for their effectiveness is inconclusive: indeed, it is not known whether treatment is even necessary.

This review found 15 randomised controlled trials which assessed the effectiveness of the interventions used to prevent ear discharge after surgery. The findings in seven low risk of bias trials (and part of an eighth) showed a reduction in the rate of ear discharge up to two weeks after the operation using either saline washouts or a single application of antibiotics at the time of the operation. A prolonged application of antibiotics was also effective. The effects were largest in studies with a high rate of ear discharge.

We conclude that the use of an intervention to prevent postoperative ear discharge should be restricted to those at a high risk of this discharge, but the choice of which treatment may be left to the surgeon.

Authors' conclusions: 

Our review found that each of the following were effective at reducing the rate of otorrhoea up to two weeks following surgery: (1) multiple saline washouts at surgery, (2) a single application of topical antibiotic/steroid drops at surgery, (3) a prolonged application of topical drops (namely antibiotic ear drops, antibiotic/steroid eardrops or aminoglycoside/steroid ear drops) and (4) a prolonged application of oral antibacterial agents/steroids. However, the rate of otorrhoea between RCTs varied greatly and the higher the rates of otorrhoea within a RCT, the smaller the NNTB for therapy.

We conclude that if a surgeon has a high rate of postoperative otorrhoea in children then either saline irrigation or antibiotic ear drops at the time of surgery would significantly reduce that rate. If topical drops are chosen, it is suggested that to reduce the cost and potential for ototoxic damage this be a single application at the time of surgery and not prolonged thereafter.

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Background: 

Grommets are frequently inserted in children's ears for acute otitis media and otitis media with effusion. A common complication is postoperative ear discharge (otorrhoea). A wide range of treatments are used to prevent the discharge, but there is no consensus on whether or not intervention is necessary nor which is the most effective intervention.

Objectives: 

To assess the effectiveness of prophylactic interventions, both topical and systemic, in reducing the incidence of otorrhoea following the surgical insertion of grommets in children.

Search strategy: 

We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; ICTRP and additional sources for published and unpublished trials. The date of the search was 3 July 2012.

Selection criteria: 

We included randomised controlled trials (RCTs) that compared the efficacy of prophylactic interventions against placebo/control and/or with other prophylactic interventions for postoperative otorrhoea in children.

Data collection and analysis: 

Two review authors independently assessed study eligibility and risk of bias, and extracted data. The outcome data were dichotomous for all the included trials. We calculated individual and pooled risk ratios (RR) using the Mantel-Haenszel fixed-effect method. We also calculated the numbers needed to treat to benefit (NNTB).

Main results: 

We found 15 eligible RCTs (2476 children, aged from four months to 17 years). We graded seven RCTs as being at a low risk of bias (n = 926 children) and for an eighth RCT we also graded two of the arms as being at a low risk of bias. We graded the other seven trials as being at a high risk of bias.

For a single application at surgery, there was evidence from two low risk of bias trials that at two weeks postoperatively the risk of otorrhoea was reduced by multiple saline washouts (from 30% to 16%; RR 0.52, 95% confidence interval (CI) 0.27 to 1.00; NNTB 7; one RCT; 140 children) and antibiotic/steroid ear drops (from 9% to 1%; RR 0.13, 95% CI 0.03 to 0.57; NNTB 13; one RCT; 322 ears). A meta-analysis of two low risk of bias trials (222 ears) failed to find an effect of a single application of antibiotic/steroid ear drops at four to six weeks postoperatively.

For a prolonged application of an intervention, there was evidence from four low risk of bias trials that the risk of otorrhoea was reduced two weeks postoperatively by antibiotic ear drops (from 15% to 8%; RR 0.54, 95% CI 0.30 to 0.97; NNTB 15; one RCT; 372 children), antibiotic/steroid ear drops (from 39% to 5%; RR 0.13, 95% CI 0.05 to 0.31; NNTB 3; one RCT; 200 children), aminoglycoside/steroid ear drops (from 15% to 5%; RR 0.37, 95% CI 0.18 to 0.74; NNTB 11; one RCT; 356 children) or oral antibacterial agents/steroids (from 39% to 5%; RR 0.13, 95% CI 0.03 to 0.51; NNTB 3; one RCT; 77 children).

Only one trial assessed the secondary outcome of ototoxicity, but no effect was found. There were no trials that assessed quality of life.

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