Epidemiology of otitis media with effusion in children.

The recently accepted international classification for otitis media was applied to a study population of 898 children less than 12 years of age having otitis media with effusion persisting at least three months. Mucoid effusion was aspirated from 48% of ears, was found more often in younger than older patients, was more often bilateral, and was a more stable state during longitudinal observation than was serous otitis media or purulent otitis media (POM). Serous otitis media occurred in only 10% of ears, but was found more often than in younger patients; POM was found in only 7% of ears. Otoscopy did not distinguish among the three effusion types. Known middle-ear pathogens were cultured more often behind red and bulging tympanic membranes from these cases of chronic effusion than behind membranes lacking these characteristics. These observations provide an epidemiologic and clinical base for further investigations of these otitis media types.