Abstract: Two randomised controlled trials recruiting a total of 413 patients met the criteria for inclusion in our review; one study had a low risk of bias and the other study had a high risk of bias. Ear plugs versus control One study recruited 201 children (aged six months to six years) who underwent myringotomy and ventilation tube insertion. The study compared an intervention group who were instructed to swim and bathe with ear plugs with a control group; the participants were followed up at one-month intervals for one year. This study, with low risk of bias, showed that the use of ear plugs results in a small but statistically significant reduction in the rate of otorrhoea from 1.2 episodes to 0.84 episodes in the year of follow-up (mean difference (MD) -0.36 episodes per year, 95% confidence interval (CI) -0.45 to -0.27). There was no significant difference in ventilation tube extrusion or hearing outcomes between the two study arms. No child required surgical intervention to remove ventilation tubes and no adverse events were reported. Water avoidance versus control Another study recruited 212 children (aged three months to 12 years) who underwent myringotomy and ventilation tube insertion. The study compared an intervention group who were instructed not to swim or submerge their heads while bathing with a control group; the participants were followed up at three-month intervals for one year. This study, with high risk of bias, did not show any evidence of a reduction or increase in the rate of otorrhoea (1.17 episodes per year in both groups; MD 0 episodes, 95% CI -0.14 to 0.14). No other outcomes were reported for this study and no adverse events were reported. Quality of evidence The overall quality (GRADE) of the body of evidence for the effect of ear plugs on the rate of otorrhoea and the effect of water avoidance on the rate of otorrhoea are low and very low respectively. The baseline rate of ventilation tube otorrhoea and the morbidity associated with it is usually low and therefore careful prior consideration must be given to the efficacy, costs and burdens of any intervention aimed at reducing this rate. While there is some evidence to suggest that wearing ear plugs reduces the rate of otorrhoea in children with ventilation tubes, clinicians and parents should understand that the absolute reduction in the number of episodes of otorrhoea appears to be very small and is unlikely to be clinically significant. Based on the data available, an average child would have to wear ear plugs for 2.8 years to prevent one episode of otorrhoea. Some evidence suggests that advising children to avoid swimming or head immersion during bathing does not affect rates of otorrhoea, although good quality data are lacking in this area. Currently, consensus guidelines therefore recommend against the routine use of water precautions on the basis that the limited clinical benefit is outweighed by the associated cost, inconvenience and anxiety. Future high-quality studies could be undertaken but may not be thought necessary. It is uncertain whether further trials in this area would change the findings of this review or have an impact on practice. Any future high-quality research should focus on determining whether particular groups of children benefit more from water precautions than others, as well as on developing clinical guidelines and their implementation.

Plain-language summary: We included two studies, recruiting a total of 413 patients. One study looked at 201 children between six months and six years who had ventilation tubes inserted to treat glue ear or recurrent infections. Children were divided into two groups: one group was allowed to swim and bathe freely, the other group was instructed to wear ear plugs while swimming or bathing. Another study looked at 212 children between three months and 12 years who had ventilation tubes inserted (we do not know precisely what for). These children were divided into two groups: one group was allowed to swim and bathe freely, the other group was instructed not to swim and told to avoid putting their head under water when bathing. Children in both studies were followed for about one year to see how many ear infections they had and if there were any other problems. We do not have any reason to be concerned about who funded these studies. The main result we looked for was the effect that keeping ears dry had on ear infections, specifically ear discharge. One study showed that there was a small reduction in the likelihood of getting an ear infection in children who protected their ears from water with ear plugs when swimming or bathing. The effect of wearing ear plugs was to reduce the number of infections a child would have every year (on average) from 1.2 to 0.84. We think the results from this study are quite reliable. Another study showed that there was no difference in the likelihood of children getting ear infections whether they were told to avoid swimming and putting their head under water, or whether they took no precautions at all. We are uncertain whether the results from this study are reliable. Neither study showed any other important differences between the children who got their ears wet and those who kept them dry. There was no effect on how long the tubes stayed in place or on hearing (although these results were only measured in one study). No harm to any participant was reported in either study. The evidence is current to September 2015. We graded the quality of evidence for the use of ear plugs as low, which means that "further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate". We have graded the quality of evidence relating to water avoidance as very low ("we are very uncertain about the estimate"). The difference that wearing ear plugs makes appears to be very small and a child would have to wear them on average for almost three years to prevent one infection resulting in ear discharge. It may be that telling children to avoid swimming and putting their head under water makes no difference to whether or not they get ear infections, but this is very uncertain. Current expert guidelines for clinicians therefore recommend against routinely using water precautions because the limited clinical benefit is outweighed by the associated cost, inconvenience and anxiety. Future high-quality studies could be undertaken but may not be thought necessary. It is uncertain whether further trials in this area would change the findings of this review or have an impact on practice. Any future high-quality research should focus on determining whether particular groups of children benefit more from water precautions than others, as well as on developing clinical guidelines and their implementation.