Risk factors for persistence of bilateral otitis media with effusion.

Otitis media with effusion (OME) is a common, episodic condition in childhood. The subset that has persistent bilateral OME is important to identify so that their management can be targeted. Most guidelines suggest a watchful-waiting period before a decision is made on the appropriateness of surgical intervention. In the UK this usually takes place in a specialist setting (otorhinolaryngology) over a period of 12 weeks. A cohort of children (n = 639), between the ages of 3.25 and 6.75 years with bilateral OME that had no previous ear or throat surgery, was followed up over 12 weeks during the recruitment phase of a multi-centre, randomised controlled study. This allowed multiple factors for persistence to be assessed. The overall spontaneous resolution rate in this cohort was between 26% and 65%, depending on the audiometric cut-off by which a persisting condition was defined. Three significant risk factors-time of year when first seen (July to December); hearing level (>or= 30 dB HL in the better ear); and a route of referral that included prior audiometry--were identified in the multivariate analysis for persistent OME both in isolation and when accompanied by each of three audiometric cut-offs (>or= 15, >or= 20 and >or= 25dB HL). In this age group, parental report of duration of OME, history of acute otitis media, parental smoking and pars tensa retractions were not significant factors for persistence. These risk factors in combination can increase the odds ratio of persistence more than sixfold. However, the proportion persisting is insufficient to bypass a period of watchful waiting, except perhaps in extreme combinations which apply to less than 7% of the cohort.