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Glue Ear - a Sticky Problem

One of the first GRiP projects involves the question of whether surgical interventions are effective in combating disability from glue ear in children. The GRiP project is to be carried out in Berkshire, and is a response to the Effectiveness Bulletin published by the School of Public Health at Leeds and Centre for Health Economics at York.

What is the problem?

Glue ear is a common cause of hearing impairment in children. It can result in a hearing loss (measured in decibels of hearing loss, dB HL) of 0 to 50 dB HL, with an average of 20 dB HL. This degree of hearing loss can turn normal speech into a whisper. If glue ear is unilateral, there usually isn't a problem, but bilateral glue ear with significant hearing loss is commonly considered to pose developmental problems to children. However, studies have not produced sufficient evidence to demonstrate a causal link between glue ear and significant hearing disability.

Persistent bilateral hearing impairment of 25-30 dB HL is sometimes thought sufficient to justify surgery.

How big is the problem?

Forty-two percent of three year olds may begin an episode of glue ear over the next twelve months. Because these episodes are usually short, the prevalence of children with glue ear is less than this, but in the 2-5 year age range 15-20% of children will have glue ear at any time. The prevalence in children older than this falls to less than 5% by age 7 years.

It is estimated that about 6% of two year olds have bilateral hearing impairment of at least 25 dB HL which persists for at least three months.

The main risk factors are:-
  • Younger age
  • More common in boys
  • Siblings with glue ear
  • Higher in Winter and Spring
  • Bottle feeding
  • Day care attendance
  • Parental smoking

What is the natural history of glue ear?

Most episodes are short. About half of affected ears resolve spontaneously after 3 months, 75% by six months, and only 5% of children will have glue ear for a year or more. In the vast majority of cases glue ear will not persist beyond early childhood.

How many children have surgery?

The average rate of surgical treatment for glue ear in England is about 5/1000 children under 15 years, and it is the most common operation in children.

There is great variation between regions and between centres within regions, which reflects a number of different issues, including screening policies, culture, referral practice and surgical decision making, and service supply.

What is the appropriate surgical intervention rate?

No one knows. That is one reason why the GRiP study is being undertaken.

Does surgery help?

Surgery for glue ear usually means surgical removal of the contents of the middle ear (myringotomy), insertion of grommets, adenoidectomy and tonsillectomy, and usually combinations of some of these.

There have been 19 published RCTs which examine the effectiveness of surgical intervention for glue ear. Those which examined hearing level as an outcome compared with no-treatment control group indicate that both grommets and adenoidectomy reduce the mean hearing impairment in children with glue ear.

However, the gains are neither large nor long-lasting. The mean reduction in hearing loss was 12 dB HL at 6 months and 6 dB HL at 12 months, though there was a very large variation, from no benefit to complete restoration of hearing.

Does surgery have problems?

Grommet insertion is not without complications, including risks associated with anaesthesia. There may be a greater risk of chronic perforation, and infection is common, with between 20 and 35% of children likely to experience discharge, and this is persistent in 5%.

When is treatment appropriate?

The big question. If children with glue ear and a hearing loss of 25dB HL or more are not treated immediately, but monitored over a period of time (watchful waiting) to establish that the condition is persistent, fewer will be treated because of the natural spontaneous resolution.

There is already some delay because of waiting lists, and to ensure that an inappropriate amount of time does not occur before surgery in those where the condition is persistent, a provisional waiting list system should be used. Children should be put on the provisional waiting list after initial audiological assessment indicates potential need for surgery and should remain on this list during the period of watchful waiting.

Retesting before surgery will also ensure that dry taps (i.e. no glue in ear at surgery) occur much less frequently, and that children are not subject to the hazards of anaesthesia and surgery for no reason.

The GRiP initiative

The programme agreed with Berkshire AHA is the following:-
  • Audit current practice to establish baseline.
  • Establish provisional waiting list and watchful waiting.
  • Establish audiology assessments at presentation, during watchful waiting, before and after surgery.
  • Monitor audological benefits and dry tap rate.
  • Audit new practice to establish change and benefit.
  • Indicate ways system can be improved.

GRiP for Glue Ear - The Future

If the study in Berkshire demonstrates that this system of dealing with glue ear provides a sensible way of delivering healthcare to the patients who need it, it will form the basis of purchaser-provider contracts for the following year for Oxfordshire, Buckinghamshire and Northamptonshire. Other regions may then also use the Berkshire GRiP initiative as the basis for their purchase of services.

The Whole Story?

Well, most of it anyway. However, glue ear seems to pop up in the most curious places - including the correspondence columns of The Times (December 28 1993).

Vice Admiral Sir Louis Le Bailly suffered from several episodes of glue ear following a war injury. Grommets helped on several occasions, but the third time glue ear occurred a Harley Street ENT consultant recommended a drug which did the trick. The Vice Admiral was told that this drug should be used in children to replace grommet operations, but that it was not available on prescription and that the manufacturer (Rhone-Poulenc Rorer) was supplying the drug free to several thousand children.

The Vice Admiral wrote to the then minister (Kenneth Clarke), using his style and title, reiterating the advice he had and commending the treatment for inclusion on the approved list. He says.....

"The answer I received was that if I was still under 18 and had had a tracheotomy the drug would be supplied".

This poses the question whether the drug (Mucodyne; carbocysteine), which does have the indication for children with glue ear, is effective.

Bandolier has found four papers on s-carboxymethylcysteine in glue ear (references below). None is particularly recent, nor did any have particularly large numbers, though three were randomised controlled trials. Statistical analysis was not profound.

Two studies showed improvement over about one month in children with bilateral glue ear, with improvements of the order of 10 dB HL occurring in more treated patients than in controls. A further study over three months (but with a high drop-out rate) showed no improvement in treatment over control.

The fourth study examined the use of s-carboxymethylcysteine in children undergoing myringotomy, with a one-month follow-up. Hearing improvement for treated children was 20 dB HL better than placebo on average.

References

Taylor & Dareshani, Br J Clin Pract 1975 29: 177-9
McGuinness, Br J Clin Pract 1977 31: 105-6.
Ramsden et al, J Laryngol and Otol 1977 9: 847-51.
Khan et al, J Laryngol and Otol 1981 95: 995-1001.

Mucodyne in glue ear

  • evidence for effectiveness insufficient: research/review needed.
  • allow to be used on a population if part of a RCT.
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